Advanced Oracle PL/SQL Developer’s - irantuto.comirantuto.com/upload/Oracle/books/advanced_oracle_plsql_developers... · Table of Contents Advanced Oracle PL/SQL Developer’s Guide

AdvancedOraclePL/SQLDeveloper’sGuideSecondEdition

TableofContents


Credits

AbouttheAuthor

AbouttheReviewers

www.PacktPub.com

Supportfiles,eBooks,discountoffers,andmore

Whysubscribe?

FreeaccessforPacktaccountholders

InstantupdatesonnewPacktbooks

Preface

Whatthisbookcovers

Whatyouneedforthisbook

Whothisbookisfor

Conventions

Readerfeedback

Customersupport

Downloadingtheexamplecode

Errata

Piracy

Questions

1.OverviewofPL/SQLProgrammingConcepts

IntroductiontoPL/SQL

PL/SQLprogramfundamentals

Cursors–anoverview

Thecursorexecutioncycle

Cursorattributes

CursorFORloop

ExceptionhandlinginPL/SQL

System-definedexceptions

User-definedexceptions

TheRAISE_APPLICATION_ERRORprocedure

Exceptionpropagation

Creatingstoredprocedures

Executingaprocedure

Functions

Functions–executionmethods

RestrictionsoncallingfunctionsfromSQLexpressions

APL/SQLpackage

OracleDatabase12cenhancementstoPL/SQLsubprograms

Managingdatabasedependencies

Displayingthedirectandindirectdependencies

Dependencymetadata

Dependencyissuesandenhancements

ReviewingOracle-suppliedpackages

OracleSQLDeveloper

OracleSQLDeveloperforDBA,Developers,andApplicationArchitects

SQLDeveloper4.0

Summary

Practiceexercise

2.Oracle12cSQLandPL/SQLNewFeatures

DatabaseconsolidationandthenewMultitenantarchitecture

TheOracleDatabase12cMultitenantarchitecture–features

MultitenantforConsolidation

Plug/unplug

ManageManyasOne

Rapidprovisioning

CDBResourceManagement

Commonusersandlocalusers

Oracle12cSQLandPL/SQLnewfeatures

IDENTITYcolumns

DefaultcolumnvaluetoasequenceinOracle12c

TheDEFAULTONNULLclause

Supportfor32KVARCHAR2

RowlimitingusingFETCHFIRST

Invisiblecolumns

Temporaldatabases

In-DatabaseArchiving

DefiningaPL/SQLsubprogramintheSELECTqueryandPRAGMAUDF

Testsetup

Comparativeanalysis

ThePL/SQLprogramunitwhitelisting

GrantingrolestoPL/SQLprogramunits

Testsetup

MiscellaneousPL/SQLenhancements

TheOracleDatabase12c(12.1.0.2)In-Memoryoption

Thechallenge

TheproblemstatementandOracleDatabase12cIn-Memory

OracleDatabase12cIn-Memoryoptionfeatures

TheOracleDatabase12cIn-MemoryArchitecture

ControllingtheIn-Memorycolumnstore

TheINMEMORYclause

Performanceoptimizations

In-MemoryAdvisor

OracleDatabaseIn-Memorybenefits

Summary

3.DesigningPL/SQLCode

Cursorstructures

Cursorexecutioncycle

Cursorattributes

Implicitcursors

Explicitcursors

Cursorvariables

Strongandweakrefcursortypes

Workingwithcursorvariables

SYS_REFCURSOR

Cursorvariablesasarguments

Cursorvariables–restrictions

Cursordesignconsiderations

Cursordesign–guidelines

ImplicitstatementresultsinOracleDatabase12c

Subtypes

Subtypeclassification

Typecompatibilitywithsubtypes

Summary

Practiceexercise

4.UsingCollections

Introductiontocollections

Collectiontypes

Associativearrays

Nestedtables

Modifyanddropanestedtableobjecttype

Designconsiderationsofanestedtable

Nestedtablestorage

Nestedtableinanindex-organizedtable

Nestedtablelocators

Nestedtableastheschemaobject

Operationsonanestedtabletypecolumn

Createanestedtableinstance

Queryinganestedtablecolumn

NestedtablecollectiontypeinPL/SQL

Collectioninitialization

Queryingthenestedtablemetadata

Nestedtablecomparisonfunctions

Multisetoperationsonnestedtables

Varray

Varrayasaschemaobject

Operationsonvarraytypecolumns

Insertingvarraycollectiontypeinstance

Queryingvarraycolumn

Updatingthevarrayinstance

VarrayinPL/SQL

Comparingthecollectiontypes

Selectingtheappropriatecollectiontype

Oracle12cenhancementstocollections

PL/SQLcollectionmethods

EXISTS

COUNT

LIMIT

FIRSTandLAST

PRIORandNEXT

EXTEND

TRIM

DELETE

Summary

Practiceexercise

5.UsingAdvancedInterfaceMethods

OverviewofExternalProcedures

ExternalProcedures

Componentsofexternalprocedureexecutionflow

Theextprocagent

TheLibraryobject

CalloutandCallback

CallSpecification

HowanExternalProcedureexecutes

Environmentsetup

TNSNAMES.ora

EXTPROC.ora

ExecutingexternalCprogramsfromPL/SQL

SecuringExternalProcedureswithOracleDatabase12c

ExecutingJavaprogramsfromPL/SQL

LoadingaJavaclassintoadatabase

StepstoexecuteaJavaclassfromanOraclePL/SQLunit

Summary

Practiceexercise

6.VirtualPrivateDatabase

OracleDatabaseSecurityoverview

Fine-GrainedAccessControl

HowFGACworks

VirtualPrivateDatabase

HowdoesVirtualPrivateDatabasework?

Column-levelVirtualPrivateDatabase

VirtualPrivateDatabasewithOracleDatabase12cMultitenant

VirtualPrivateDatabasecomponents

ApplicationContext

VirtualPrivateDatabasepolicyfunction

Policytypes

TheDBMS_RLSpackage

Demonstration

VirtualPrivateDatabasefeaturesandbestpractices

VirtualPrivateDatabasemetadata

Policyutilities—refreshanddrop

OracleDatabase12cSecurityenhancements

OracleDatabase12cDataRedaction

DataRedactionexemptionsandmiscellaneousfeatures

DataRedactionfunctiontypes

Demonstration

TheDataRedactionmetadata

Summary

Practiceexercise

7.OracleSecureFiles

IntroductiontoLargeObjects

ClassificationofLargeObjectdatatypes

InternalLOB

PersistentandTemporaryLOB

ExternalLOB

LOBrestrictions

LOBdatatypesinOracle

BLOBandCLOB

BFILE

Somemorerelatedstuff

TheLOBlocator

LOBinstanceinitialization

TheDBMS_LOBpackage

TheDBMS_LOBconstants

TheDBMS_LOBdatatypes

TheDBMS_LOBsubprograms

LOBusagenotes

OracleSecureFiles

Deduplicationandcompression

Encryption

FileSystemLogging

WriteGatherCache

Freespacemanagement

BasicFilesandSecureFiles

Thedb_securefileparameter

WorkingwithLOBs

LOBmetadata

EnablingtheadvancedfeaturesofaSecureFile

PopulatingtheLOBdata

TemporaryLOBoperations

ManagingtemporaryLOBs

WorkingwithatemporaryLOB

MigratingLONGtoLOBs

UsetheALTERTABLEcommand

UsingtheTO_LOBfunction

OnlineTableRedefinition

MigratingBasicFilestoSecureFiles

OracleDatabase12cenhancementstoSecureFiles

Summary

Practiceexercise

8.TuningthePL/SQLCode

ThePL/SQLCompiler

SubprograminlininginPL/SQL

PRAGMAINLINE

PLSQL_OPTIMIZE_LEVEL

Case1:WhenPLSQL_OPTIMIZE_LEVEL=0




Nativeandinterpretedcompilationtechniques

OracleDatabase11gRealNativeCompilation

Selectingtheappropriatecompilationmode

Settingthecompilationmode

Queryingthecompilationsettings

Compilingaprogramunitfornativeorinterpretedcompilation

RecompilingadatabaseforaPL/SQLnativeorinterpretedcompilation

TuningPL/SQLcode

Buildsecureapplicationsusingbindvariables

Callparametersbyreference

Avoidinganimplicitdatatypeconversion

UnderstandingtheNOTNULLconstraint

Selectionofanappropriatenumericdatatype

BulkprocessinginPL/SQL

BULKCOLLECT

FORALL

FORALLandexceptionhandling

Summary

Practiceexercise

9.ResultCache

OracleDatabase11gResultCache

WhatistheServerResultCache?

ConfiguringtheServerResultCache

ResultCacheversusBufferCache

ResultCacheversusOracle12cDatabaseIn-Memory

ResultCacheversusIn-MemoryDatabaseCache

SQLqueryResultCache

MonitoringtheSQLResultCache

InvalidationoftheSQLResultCache

ReadconsistencyoftheSQLResultCache

Limitations

PL/SQLFunctionResultCache

Doesitsoundsimilartodeterministicfunctions?

DifferencesbetweenResultCacheandothercachingtechniques

Illustration

MonitoringthePL/SQLResultCache

InvalidationofthePL/SQLResultCache

Limitation

OCIClientresultscache

TheDBMS_RESULT_CACHEpackage

Displayingtheresultcachememoryreport

OracleDatabase12cenhancementstothePL/SQLfunctionResultCache

ResultcacheinRealApplicationClusters

Summary

Practiceexercise

10.Analyzing,Profiling,andTracingPL/SQLCode

AsamplePL/SQLprogram

TrackingPL/SQLcodinginformation

USER_ARGUMENTS

USER_OBJECTS

USER_OBJECT_SIZE

USER_SOURCE

USER_PROCEDURES

USER_PLSQL_OBJECT_SETTINGSandUSER_STORED_SETTINGS

USER_DEPENDENCIES

TheDBMS_DESCRIBEpackage

Trackingtheprogramexecutionsubprogramcallstack

TrackingpropagatingexceptionsinPL/SQLcode

Determiningidentifiertypesandusages

USER_IDENTIFIERS

ThePL/Scopetool

ThePLSCOPE_SETTINGSparameter

TheDBMS_METADATApackage

DBMS_METADATAdatatypesandsubprograms

Parameterrequirements

TheDBMS_METADATAtransformationparametersandfilters

Demonstration

TracingPL/SQLprogramsusingDBMS_TRACE

InstallingtheDBMS_TRACEpackage

DBMS_TRACEsubprograms

CompilingaPL/SQLprogramfordebugging

ViewingthePL/SQLtraceinformation

StepstotracePL/SQLprogramexecution

ProfilingPL/SQLcode

TheDBMS_HPROFpackage

DifferencesbetweenDBMS_PROFILERandDBMS_HPROF

DBMS_HPROFsubprograms

Collectingrawprofiledata

Interpretingtherawprofilerdata

Analyzingprofilerdata

Creatingtheprofilertables

Analyzingtheprofileroutput

Queryingtheprofilertables

Theplshprofutility

Whatdothesereportsreveal?

Summary

Practiceexercise

11.SafeguardingPL/SQLCodeagainstSQLinjection

WhatisSQLinjection?

SQLinjectiontargets

HowtoexploitthePL/SQLcode?

PreventingSQLinjectionattacks

SanitizinginputsusingDBMS_ASSERT

Choosetherightsubprogramfortherightidentifier

Unquotedidentifiers

Quotedidentifiers

Literals

DBMS_ASSERT–limitations

Useofbindvariablestopreventinjectionattacks

BestpracticestoavoidSQLinjection

TestingthecodeforSQLinjectionflaws

Teststrategy

Aneffectivecodereview

Staticcodeanalysis

Fuzztools

Generatingtestcases

Summary

Practiceexercise

12.WorkingwithOracleSQLDeveloper

AnoverviewofSQLDeveloper

Keydifferentiators

Historyandbackground

SQLDeveloperforDevelopers

SQLDeveloperforDatabaseAdministrators

SQLcl–ThenewSQLcommandline

GettingstartedwithSQLDeveloper

Creatingadatabaseconnection

UsingtheSQLworksheet

CorefeaturesofSQLDeveloper

ObjectBrowser

PL/SQLEditorandDebugger

DBAPanel

DatabaseUtilities

TheDataModeler

SQLDeveloperreports

Versioncontrol

TheSQLTranslationFramework

SQLDeveloper4.0and4.1NewFeatures

Summary

Index


AdvancedOraclePL/SQLDeveloper’sGuideSecondEditionCopyright©2016PacktPublishing

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CreditsAuthor

SaurabhK.Gupta

Reviewers

KamranAghayevA

PatrickBarel

NassyamBasha

RamakrishnaKandula

WissemELKhlifi

SeanStacey

DavorZelic

CommissioningEditor

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AbouttheAuthorSaurabhK.Guptaisaseasoneddatabasetechnologistwithextensiveexperienceindesigninghighperformanceandhighlyavailabledatabaseapplications.HistechnologyfocushasbeencenteredaroundOracleDatabasearchitecture,OracleCloudplatform,DatabaseIn-Memory,DatabaseConsolidation,Multitenant,Exadata,BigData,andHadoop.Hehasauthoredthefirsteditionofthisbook.HeisanactivespeakerattechnicalconferencesfromOracleTechnologyNetwork,IOUGCollaborate‘15,AIOUGSangam,andTechDays.Connectwithhimonhistwitterhandle(orSAURABHKG)orthroughhistechnicalblogwww.sbhoracle.wordpress.com,withcomments,suggestions,andfeedbackregardingthisbook.

http://www.sbhoracle.wordpress.com

AbouttheReviewersPatrickBarelisaPL/SQLdeveloperforAMISServices(http://www.amis.nl/)intheNetherlands.BesidesworkingwithSQLandPL/SQL,heco-developedCodeGentogetherwithStevenFeuerstein,andhaswrittendifferentplugins(http://bar-solutions.com/)forPL/SQLdeveloperat(http://www.allroundautomations.com/).HepublishesarticlesonAMISTechnologyBlog(http://technology.amis.nl/blog)andonhisownblog(http://blog.bar-solutions.com).

HehasbeenareviewerforseveralbooksincludingOraclePL/SQLProgrammingbyStevenFeuerstein.HehasbeenanOracleACEsince2011.

NassyamBashaisadatabaseadministratorandanOracleACEDirector.Heholdsamaster’sdegreeinComputerApplicationsfromtheUniversityofMadras.HeisanOracle11gCertifiedMasterandExadataimplementationspecialist,andhasgoodknowledgeofOracletechnologies,suchasDataGuard,RMAN,RAC,andExadata.HeactivelyparticipatesinOracle-relatedforums,suchasOTN,wherehehassuperherostatus.HemaintainsanOracle-technology-relatedblog(www.oracle-ckpt.com)andhascoauthoredOracleDataGuard11gR2administrationbeginnersguide,PacktPublishing.HeactivelywritesmanyarticlesonOTNinvariouslanguages.HeisaspeakeratOTN,IOUG,andSANGAM,andheistheco-founderofOraworld-team(www.oraworld-team.com).HeispartoftheAIOUGcommunityonTwitter,whereheoccasionallyexpresseshisviewsviatheTwitterhandle@AIOUG.HeiscurrentlyworkingwithPythianasanOracledatabaseconsultant.

NassyamBashahaswrittenOracleDataGuard11gR2Beginner’sGuide,PacktPublishing.

IwanttothankthealmightyAllahandmyparents,AbdulAleemandRahimunnisa,fortheirsupportandblessingsallthetime—withoutthem,nothingispossible.Specialthankstomywifeand9-month-olddaughterYashfeenFathima,who’vesharedalotoffunandcrazythingswithmewhileIworkedonthisbook,and,asalways,Iwouldalsoliketothankmybrother,Nawaz,andmycousins,fortheirgreatsupport.Finally,thankstoSaurabhGuptaforreferringmeasatechnicalreviewer,whichwasnotaneasytaskforme,asthisismyfirstassignmentasareviewer.Hedidagreatjobonthisbook.

WissemElKhlifiisthefirstOracleACEinSpainandanOracleCertifiedProfessionalDBAwithover12yearsofITexperience.

HeearnedhisComputerScienceengineeringdegreefromFSTTunisia,hismaster’sdegreeinComputerSciencefromtheUPC,Barcelona,andanothermaster’sdegreeinBigDataSciencefromtheUPC,Barcelona.

HisareasofinterestareLinuxSystemAdministration,OracleERPandDatabases(RACandDataguard),bigdataNoSQLdatabasemanagement,andbigdataanalysis.

HiscareerhasincludedtherolesofOracleandJavaanalyst/programmer,OracleDBA,architect,teamleader,andbigdatascientist.Hecurrentlyworksasseniordatabaseand

http://www.amis.nl/

http://bar-solutions.com/

http://www.allroundautomations.com/

http://technology.amis.nl/blog

http://blog.bar-solutions.com

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http://www.oraworld-team.com

applicationengineerforSchneiderElectric/APC.

Hewritesnumerousarticlesonhiswebsite,http://www.oracle-class.com,andyoucancontacthimviaTwitterat@orawiss.

DavorZelicisanITprofessionalwithmorethan15yearsofexperienceindesigning,developing,andimplementingITsystems.

Aftergettinghismaster’sdegreeinElectricalEngineering,hebeganhisprofessionalcareerworkingwithOracletechnologyintheCroatianITcompanyTEBInformatika.Formorethan10years,DavorworkedonITprojectsrelatedtoroadmanagement,wherehegainedextensiveexperienceworkingasanOracleSQL,PLSQL,Forms,andReportsandSpatialdeveloper.HehasprovedhisknowledgebybecominganOracleCertifiedProfessionalissuedbytheOracleCorporation.

ApartfromOracletechnology,Davorhasgainedexpertiseindesignanddevelopmentofgeographicinformationsystemsforcollection,storage,transformation,analysis,andvisualizationofgeo-referenceddata.HeoriginallyworkedwithIntergraphtechnology,butlaterhisfocusmovedtoopensourceGIStechnologies,suchasGeoserverandOpenLayers.

DavorcurrentlyworksasasoftwarearchitectattheITdepartmentofCroatianCentralBank,designingsoftwaresolutionsforCroatianfinancialmarketdatacollectionandanalysis.

Iwanttothankmyparentsforthesupportthattheygavemeinchoosingmyeducationalpath,whichallowedmetofindajobthatisnotjustaroutine,butalsoasourceofsatisfactionandconstantchallenge.

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PrefaceHowmanyofuswouldbelievethatPL/SQLwasintroducedasascriptinglanguageforexecutingabunchofSQLscripts?Well,that’strue.Withthegrowingneedtobuildcomputationallogicandcondition-basedconstructs,andtomanageexceptionruleswithindatabases,OracleCorporationfirstreleasedPL/SQLalongwithOracleDatabaseVersion6.0withalimitedsetofcapabilities.Withinitscapacity,PL/SQLwascapableofcreatingprogramunitsthatcouldnotbestoredinsidethedatabase.Eventually,Oracle’sreleaseintheapplicationline,SQL*FormsversionV3.0,includedthePL/SQLengineandalloweddeveloperstoimplementtheapplicationlogicthroughprocedures.Backthen,PL/SQLusedtobepartofthetransactionprocessingoptioninOracle6andtheproceduraloptioninOracle7.Sincethetimeofitsingenuousbeginning,PL/SQLhasmaturedimmenselyasastandardfeatureofOracleDatabase.Ithasbeenenthusiasticallyreceivedbythedevelopercommunity,andthecreditgoestoitssupportforadvancedelementssuchasmodularprogramming,encapsulation,supportforobjectsandcollections,programoverloading,nativeanddynamicSQL,andexceptionhandling.

PL/SQLislooselyderivedfromAda(namedafterAdaLovelace,anEnglishmathematicianwhoisregardedasthefirstcomputerprogrammer),ahigh-levelprogramminglanguage,whichcomplieswiththeadvancedprogrammingelements.Buildingadatabasebackendforanapplicationdemandstheabilitytodesignthedatabasearchitecture,skillstocodecomplexbusinesslogics,andexpertiseinadministeringandprotectingthedatabaseenvironment.OneoftheprincipalreasonswhyPL/SQLisakeyenablerinthedevelopmentphaseisitstightintegrationwithOracle’sSQLlanguage.Inadditiontothis,itprovidesarichplatformforimplementingthebusinesslogicintheOracleDatabaselayerandstorethemasproceduresorfunctionsforsubsequentuse.Asaprocedurallanguage,PL/SQLprovidesadiverserangeofdatatypes,iterativeandcontrolconstructs,conditionalstatements,andexceptionhandlers.

Inastandardsoftwaredevelopmentspace,anOracledatabasedeveloperisexpectedtogetinvolvedinschemadesign;codebusinesslogicsontheserversidebyusingfunctions,procedures,orpackages;implementactionrulesbyusingtriggers;andsupportclient-sideprogramsinsettinguptheapplicationinterface.Whilebuildingtheserver-sidecode,developersshouldunderstandthattheircodecontributestotheapplication’sperformanceandscalability.Languagebasicsareexpectedtoberesilient,butwhilebuildingrobustandsecureapplicationsusingPL/SQL,developersmusttakeadvantageofbestpracticesandtrytouseadvancedlanguagefeatures.ThisbookfocusesontheadvancedfeaturesofPL/SQLvalidateduptothelatestOracleDatabase12c.

Learningbyexamplehasalwaysbeenawell-attestedapproachfordivingdeepintoaconcept.ThisbookwillenableyoutomasterthelatestenhancementsandnewfeaturesofOracleDatabase12c.Forefficientreading,youjusthavetobefamiliarwiththePL/SQLfundamentalssothatyoucanrelatetotheevolutionofanadvancedfeaturefromitsever-expandingroots.

ThisbookcloselyfollowstheoutlineoftheOracleUniversitycertification;thatis,the

OracleCertifiedAdvancedPL/SQLDeveloperProfessional(1Z0-146)exam.Oneofthemostsoughtaftercertificationsinthedevelopercommunity,the1Z0-146certification’sobjectivesarequitecomprehensive,andtouchuponthevariousprogressiveareasofPL/SQL.Tonameafew,PL/SQLcodeperformance,maintenance,bulkprocessingtechniques,PL/SQLcollections,securityimplementation,andthehandlingoflargeobjects.Forcertificationaspirants,thisbookwillserveasaone-stopexamguide.Atmanystages,thisbookgoesbeyondthecertificationobjectivesandattemptstobuildadeepunderstandingoftheconcepts.Therefore,mid-leveldatabasedeveloperswillfindthisbookahandylanguagereferenceandwouldbekeentohaveitontheirbookshelves.

Mylastworkonthesamesubjectwillremainclosetomyheart,butthisoneisstraightfrommyexperience.IhopethatthisbookwillhelpyouimproveyourPL/SQLdevelopmentskillsandgainconfidenceinusingadvancedfeatures,alongwithmeticulousfamiliarizationofOracleDatabase12c.

“Theonlyrealsecuritythatamancanhaveintheworldisareserveofknowledge,experienceandability”

—HenryFord

WhatthisbookcoversChapter1,OverviewofPL/SQLProgrammingConcepts,providesanoverviewofPL/SQLfundamentals.Itrefreshesthebasicconcepts,suchasPL/SQLlanguagefeatures,theanonymousblockstructure,exceptionhandling,andstoredsubprograms.

Chapter2,Oracle12cSQLandPL/SQLNewFeatures,talksaboutthenewfeaturesofOracleDatabase12c.ItstartswiththeideaofconsolidationofdatabasesonacloudandhowtheOracle12cMultitenantarchitectureaddressestherequirements.ItconsolidatesthenewfeaturesinOracle12cSQLandPL/SQL,andexplainseachofthemwithexamples.ItwillhelpyoutofeeltheessenceofOracleDatabase12candunderstandwhatthedrivingwheelofinnovationis.AsectionontheOracleDatabase12cIn-memoryoptionwillfamiliarizeyouwiththebreakthroughfeatureintheanalyticsandwarehousespace.

Chapter3,DesigningPL/SQLCode,primarilyfocusesonthePL/SQLcursor’sdesignandhandling.Youwillgettolearnthebasicsofcursordesign,cursortypesandcursorvariables,handlingcursorsinPL/SQL,anddesignguidelines.ThischapterwillalsoincludetheenhancementsmadebyOracleDatabase12cwithrespecttocursors.

Chapter4,UsingCollections,introducesyoutotheworldofcollections;namely,associativearrays,nestedtables,andvarrays.TakingyouallthewayfromtheircreationinSQLandPL/SQLtodesignconsiderations,thischaptermakesyouwiseenoughtochoosetherightcollectiontypeinagivensituation.AsectiononOracleDatabase12cenhancementstocollectionsintroducesaveryhandyfeaturethatwillallowyoutojoinatableandcollection.

Chapter5,UsingAdvancedInterfaceMethods,focusesonapowerfulfeatureofPL/SQL:howtoexecuteexternalproceduresinPL/SQL.YouwilllearnandunderstandthespecificsofexecutingaCorJavaprograminPL/SQLasanexternalprocedurethroughstep-by-stepdemonstration.ThischapteralsomentionstheOracleDatabase12cenhancementwhichallowsyoutosecureexternalproceduresthroughanadditionalsafetynet.

Chapter6,VirtualPrivateDatabase,providesadetailedoverviewoftheOracleDatabaseSecurityDefense-in-deptharchitectureandfocusesononeofthedeveloper-centricfeatures,knownastheVirtualPrivateDatabase.OracleDatabase12csecurityenhancementsandademonstrationofdataredactionwillmakeyouunderstandOracle’ssecurityofferings.

Chapter7,OracleSecureFiles,providesathoroughunderstandingofhandlinglargeobjectsinOracleandfocusesonstorageoptimizationsmadebySecureFiles.IntroducedinOracle11g,SecureFilesisthenewstoragemechanismthatscoreshighonitsadvancedfeatures,suchascompression,encryption,anddeduplication.ThischapteralsohelpsyouwiththerecommendedmigrationmethodsfromolderLOBstoSecureFiles.

Chapter8,TuningthePL/SQLCode,introducesthebestpracticesfortuningPL/SQLcode.ItstartswiththePL/SQLoptimizerandrollsthroughthebenefitsofnative

compilation,PL/SQLcodewritingskills,andcodeevaluationdesign.ThischapterincludesthechangesinOracle12cwithrespecttolargeobjecthandling.

Chapter9,ResultCache,explainstheresultcachingfeatureinOracleDatabase.ItisapowerfulcachingmechanismthatenhancestheperformanceofSQLqueriesandPL/SQLfunctionsthatarerepeatedlyexecutedontheserver.ThischapteralsodiscussestheenhancementsmadetothefeatureinOracleDatabase12c.

Chapter10,Analyzing,Profiling,andTracingPL/SQLCode,detailsthetechniquesusedtoanalyze,profile,andtracePL/SQLcode.IfyouaretroubleshootingPL/SQLcodeforperformance,youmustlearntheprofilingandtracingtechniques.Inanenterpriseapplicationenvironment,thesepracticesarevitalweaponsinadeveloper’sarsenal.

Chapter11,SafeguardingPL/SQLCodeagainstSQLinjection,describeswaystoprotectyourPL/SQLfrombeingattacked.Avulnerablepieceofcodeispronetomaliciousattacksandrunstheriskofgivingawaysensitiveinformation.Efficientcodewritingandproofingthecodefromexternalattackscanhelptominimizingtheattacksurfacearea.Inthischapter,youwilllearnthepracticesforsafeguardingyourcodeagainstexternalthreats.

Chapter12,WorkingwithOracleSQLDeveloper,describesthebenefitsoftheOracleSQLDeveloperfordevelopers,databaseadministrators,andarchitects.ThischapternotonlyhelpsyougetstartedwithSQLDeveloper,butalsohelpsyougainabetterunderstandingofthenewfeaturesofSQLDeveloper4.0and4.1.

WhatyouneedforthisbookIfyouaregoodwithPL/SQLdevelopmentbasics,I’msureyouwillenjoyreadingthisbook.YouwilllearnnewwaystoprogramefficientlyinPL/SQL.

WhothisbookisforThisbookisforOracledeveloperswhoareresponsiblefordatabasemanagement.ReadersareexpectedtohavebasicknowledgeoftheOracleDatabaseandthefundamentalsofPL/SQLprogramming.Certificationaspirantscanusethisbooktoprepareforthe1Z0-146examinationinordertobecomeanOracleCertifiedProfessionalinAdvancedPL/SQL.

ConventionsInthisbook,youwillfindanumberofstylesoftextthatdistinguishbetweendifferentkindsofinformation.Herearesomeexamplesofthesestyles,andanexplanationoftheirmeaning.

Codewordsintext,databasetablenames,foldernames,filenames,fileextensions,pathnames,dummyURLs,userinput,andTwitterhandlesareshownasfollows:“ThemodifiedSELECTqueryisthenexecutedintheHRschemaofthedatabase.”

Ablockofcodeissetasfollows:

/*Createthestoredproceduretosetthecontextattribute*/

CREATEORREPLACEPROCEDUREp_app_context(p_valVARCHAR2)

IS

BEGIN

/*CreateanamespaceDEMO_CONTEXT*/

DBMS_SESSION.SET_CONTEXT(

NAMESPACE=>'DEMO_CONTEXT',

ATTRIBUTE=>'COUNTRY',

VALUE=>P_VAL);

END;

/

Newtermsandimportantwordsareshowninbold.Wordsthatyouseeonthescreen,inmenusordialogboxesforexample,appearinthetextlikethis:“Thisishowinterpretedcompilationworks.Inthecaseofnativecompilation,,asharabledynamiclinkedlibrary(DLL)isgeneratedinsteadofamachinecode.”

NoteWarningsorimportantnotesappearinaboxlikethis.

TipTipsandtricksappearlikethis.

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Chapter1.OverviewofPL/SQLProgrammingConceptsStructuredQueryLanguage(SQL)isalanguagethathasbeenwidelyacceptedandadoptedforaccessingrelationaldatabases.Thislanguageallowsuserstoperformdatabaseoperationssuchasreading,creating,modifying,anddeletingthedata.Sincethesummerof1970,whenDr.E.F.CoddpublishedthepaperARelationalModelofDataforLargeSharedDataBanksfortheACMjournal,thelanguagehasmaturedcomprehensivelyasanindustrystandard.Withitsbroadrangeoffeaturesandeasyadaptationtoenterpriseenvironments,theSQLlanguagehasbeentypicallyregardedasthemostreliablelanguageforinteractingwithrelationaldatabases.

PL/SQLwasdevelopedin1991byOracleCorporationasaprocedurallanguageextensiontoSQL.ItsabilitytointegrateseamlesslywithSQLmakesitapowerfullanguagetoconstructthedataaccesslayerandtherichproceduralextensionshelpintranslatingbusinesslogicwithintheOracleDatabase.ThisfirstchapterintroducesyoutothePL/SQLlanguageandrefreshessomeofthekeyprogrammingconcepts.Thechapterisoutlinedasfollows:

IntroductiontoPL/SQLRecapitulateprocedures,functions,packages,andcursorsExceptionhandlingObjectdependenciesMajorOraclesuppliedpackagesOracleDevelopmenttools—SQLDeveloperandSQL*Plus

IntroductiontoPL/SQLPL/SQLstandsforProceduralLanguage-StructuredQueryLanguage(PL/SQL).ItispartoftheOracleDatabaseproduct,whichmeansnoseparateinstallationisrequired.Itiscommonlyusedtotranslatebusinesslogicinthedatabaseandexposetheprograminterfacelayertotheapplication.WhileSQLispurelyadataaccesslanguagethatdirectlyinteractswiththedatabase,PL/SQLisaprogramminglanguageinwhichmultipleSQLsandproceduralstatementscanbegroupedinaprogramunit.PL/SQLcodeisportablebetweenOracleDatabases(subjecttolimitationsimposedbyversions).Thebuilt-indatabaseoptimizerrefactorsthecodetoimprovetheexecutionperformance.

TheadvantagesofPL/SQLasalanguageareasfollows:

PL/SQLsupportsalltypesofSQLstatements,datatypes,staticSQL,anddynamicSQLPL/SQLcoderunsonallplatformssupportedbytheOracleDatabasePL/SQLcodeperformancecanbeimprovedbytheuseofbindvariablesindirectSQLqueriesPL/SQLsupportstheobject-orientedmodeloftheOracleDatabasePL/SQLapplicationsincreasescalabilitybyallowingmultipleuserstoinvokethesameprogramunit

Althoughitisnotusedtobuilduserinterfaces,itprovidestheopportunitytobuildrobust,secure,andportableinterfacelayers,whichcanbeexposedtoahigh-levelprogramminglanguage.SomeofthekeyfacultiesofPL/SQL(PL/SQLaccomplishments)arelistedhere:

Aprocedurallanguage:APL/SQLprogramcanincludealistofoperationsthatcanexecutesequentiallytogetthedesiredresult.UnlikeSQL,whichisjustadeclarativelanguage,PL/SQLaddsselectiveanditerativeconstructstoit.Databaseprogramminglanguage:Serversideprogramsrunfasterthanthemiddle-tierprograms.Codemaintenancebecomeseasyasitneedstobere-writtenlessfrequently.Anintegrallanguage:ApplicationdeveloperscaneasilyintegrateaPL/SQLprogramwithotherhigh-levelprogramminginterfacessuchasJava,C++,or.NET.ThePL/SQLproceduresorsubprogramscanbeinvokedfromclientprogramsasexecutablestatements.

PL/SQLprogramfundamentalsAwell-writtenPL/SQLprogramshouldbeabletoanswerthefollowingfundamentalquestions:

HowdowehandleanSQLexecutionintheprogram?Howdowehandletheproceduralexecutionflowintheprogram?Doestheprogramhandletheexceptions?Howdowemaintain(traceanddebug)thePL/SQLprogramcode?

Well,therearemultipletipsandtechniquestostandardizePL/SQLcodingpractices.Butbeforewedrilldowntotheprogrammingskills,letusfamiliarizeourselveswiththestructureofaPL/SQLprogram.APL/SQLprogramcanbebrokendownintofoursections.Eachsectioncarriesaspecificobjectiveandmustexistinthesamesequenceinaprogram.Letushaveabrieflookatthesections:

Header:Thisisanoptionalsectionwhichisrequiredfornamedblockssuchasprocedures,functions,andtriggers.Itcontainstheprogramname,theprogram’sowner,andtheparameterspecification.Declaration:Thisisanoptionalsectionusedtodeclarelocalvariables,cursors,andlocalsubprogramsthatarelikelytobeusedintheprogrambody.TheDECLAREkeywordindicatesthebeginningofthedeclarationsection.ThesectioncanbeskippedifthePL/SQLprogramusesnovariables.Execution:Thisistheproceduralsectionoftheprogramandcomprisesthemainprogrambodyandanexceptionsection.TheBEGINandENDkeywordsindicatethebeginningandendoftheprogrambody.Itmustcontainatleastoneexecutablestatement.Duringblockexecution,thesestatementsareparsedandsequentiallyexecutedbythePL/SQLengine.Exception:Thisisanoptionalsectionintheprogrambodythatcontainsasetofinstructionsasproceduralstatements,forvariouserrors,thatmayoccurintheprogramleadingtoabnormaltermination.Theprogramcontrollandsintotheexceptionsectionandtheappropriateexceptionhandlerisexecuted.TheEXCEPTIONkeywordindicatesthestartoftheexceptionsection.

ThefollowingblockdiagramshowsthestructureofaPL/SQLblock:

APL/SQLblockistheelementaryunitofaprogramthatgroupsasetofproceduralstatements.BasedonthesectionsincludedinaPL/SQLprogramunit,wecanclassifyaprogramunderfollowingcategories:

AnonymousPL/SQLblock:ThisisthesimplestPL/SQLprogramthathasnoname,buthasitsDECLARE-BEGIN-ENDskeleton.ItcaneitherberunforcurrentexecutionasstandaloneblockorembeddedlocallywithinaPL/SQLprogramunit.Ananonymousblockcannotbestoredinthedatabase.Named:ThisblockisanamedPL/SQLroutinethatisstoredpersistentlyinthedatabaseasaschemaobject.Itcanbeinvokedeitherfromadatabasesessionorbyanotherprogramunit.AnamedPL/SQLprogramcanbeafunction,procedure,trigger,orpackage.Nested:AblockwithinanotherPL/SQLblockformsanestedblockstructure.

So,let’sgetstartedwithourfirstanonymousPL/SQLblock.Theblockdeclaresastringanddisplaysitonscreen.Notethateachlineintheprogramendswithasemi-colonandtheblockendswithaslash(/)forcodeexecution.

/*EnabletheServeroutputtodisplayblockmessages*/

SETSERVEROUTPUTON

NoteTheSERVEROUTPUTparameterisaSQL*Plusvariablethatenablestheprintingof

DBMS_OUTPUTmessagesfromaPL/SQLblock.

/*StartthePL/SQLblock*/

DECLARE

/*Declarealocalvariableandinitializewithadefaultvalue*/

L_STRVARCHAR2(50):='IamnewtoPL/SQL';

BEGIN

/*Printtheresult*/

DBMS_OUTPUT.PUT_LINE('ISaid-'||L_STR);

END;

/

ISaid-IamnewtoPL/SQL

PL/SQLproceduresuccessfullycompleted.

Cursors–anoverviewWritingSQLinPL/SQLisoneofthecriticalpartsofdatabaseprogramming.AllSQLstatementsembeddedwithinaPL/SQLblockareexecutedasacursor.Acursorisaprivatememoryarea,temporarilyallocatedinthesession’sUserGlobalArea(UGA),thatisusedforprocessingSQLstatements.TheprivatememorystorestheresultsetretrievedfromtheSQLexecutionandcursorattributes.Cursorscanbeclassifiedasimplicitandexplicitcursors.

OraclecreatesanimplicitcursorforalltheSQLstatementsincludedintheexecutablesectionofaPL/SQLblock.Inthiscase,thecursorlifecycleismaintainedbytheOracleDatabase.

Forexplicitcursors,theexecutioncyclecanbecontrolledbytheuser.DatabasedeveloperscanexplicitlydeclareanimplicitcursorundertheDECLAREsectionalongwithaSELECTquery.

ThecursorexecutioncycleAcursormovesthroughthefollowingstagesduringexecution.Notethat,inthecaseofanimplicitcursor,allthestepsarecarriedoutbytheOracleDatabase.Let’stakeaquicklookattheexecutionstagesOPEN,FETCH,andCLOSE.

TheOPENstageallocatesthecontextareainthesession’sUserGlobalAreaforperformingSQLprocessing.TheSQLprocessingstartswithparsingandbinding,followedbystatementexecution.InthecaseoftheSELECTquery,therecordpointerpointstothefirstrecordintheresultset.TheFETCHstagepullsthedatafromthequeryresultset.Iftheresultsetisamulti-recordset,therecordpointermovesincrementallywitheveryfetch.Thefetchstageisaliveuntilthelastrecordisreachedintheresultset.TheCLOSEstageclosesthecursor,flushesthecontextarea,andreleasesthememorybacktotheUGA.

CursorattributesCursorattributesholdtheinformationaboutthecursorprocessingateachstageofitsexecution:

%ROWCOUNT:NumberofrowsfetcheduntilthelastfetchorimpactedbythelastDMLoperation.ApplicableforSELECTaswellasDMLstatements.%ISOPEN:BooleanTRUEifthecursorisstillopen,ifnotFALSE.Foranimplicitcursor,thisattributeisalwaysFALSE.%FOUND:BooleanTRUE,ifthefetchoperationswitchesandpointstoarecord;ifnot,FALSE.%NOTFOUND:BooleanFALSEwhenthecursorpointerswitchesbutdoesnotpointtoarecordintheresultset.

Note%ISOPENistheonlycursorattributethatisaccessibleoutsidethecursorexecutioncycle.

Thefollowingprogramusesthecursorattributes%ISOPEN,%NOTFOUND,and%ROWCOUNTtofetchthedatafromtheEMPtableanddisplayit:

/*EnabletheSERVEROUTPUTtodisplayblockmessages*/

SETSERVEROUTPUTON

/*StartthePL/SQLBlock*/

DECLARE

/*Declareacursortoselectemployeesdata*/

CURSORC_EMPIS

SELECTEMPNO,ENAME

FROMEMP;

L_EMPNOEMP.EMPNO%TYPE;

L_ENAMEEMP.ENAME%TYPE;

BEGIN

/*Checkifthecursorisalreadyopen*/

IFNOTC_EMP%ISOPENTHEN

DBMS_OUTPUT.PUT_LINE('***DisplayingEmployeeInfo***');

ENDIF;

/*Openthecursoranditerateinaloop*/

OPENC_EMP;

LOOP

/*Fetchthecursordataintolocalvariables*/

FETCHC_EMPINTOL_EMPNO,L_ENAME;

EXITWHENC_EMP%NOTFOUND;

/*Displaytheemployeeinformation*/

DBMS_OUTPUT.PUT_LINE(chr(10)||'DisplayInformationfor

employee:'||C_EMP%ROWCOUNT);

DBMS_OUTPUT.PUT_LINE('EmployeeId:'||L_EMPNO);

DBMS_OUTPUT.PUT_LINE('EmployeeName:'||L_ENAME);

ENDLOOP;

END;

/

***DisplayingEmployeeInfo***

DisplayInformationforemployee:1

EmployeeId:7369

EmployeeName:SMITH


EmployeeId:7499

EmployeeName:ALLEN


EmployeeId:7521

EmployeeName:WARD


EmployeeId:7566

EmployeeName:JONES

….


CursorFORloopLoopingthroughalltherecordsofacursorobjectcanbefacilitatedwiththeuseoftheFORloop.AFORloopopeningacursordirectlyisknownasaCURSORFORloop.TheusageoftheCURSORFORloopreducestheoverheadofmanuallyspecifyingtheOPEN,FETCH,andCLOSEstagesofacursor.

TheCURSORFORloopwillbestcompactthecodewhenworkingwithmulti-rowexplicitcursors.ThefollowingPL/SQLblockdemonstratesthepurpose:

/*EnabletheSERVEROUTPUTparametertoprinttheresultsinthe

environment*/

SETSERVEROUTPUTON


DECLARE

/*Declareanexplicitcursortoselectemployeeinformation*/

CURSORCUR_EMPIS

SELECTename,sal

FROMemp;

BEGIN

/*FORLoopusesthecursorCUR_EMPdirectly*/

FOREMPINCUR_EMP

LOOP

/*Displaymessage*/

DBMS_OUTPUT.PUT_LINE(EMP.ename||'earns'||EMP.sal||'permonth');

ENDLOOP;

END;

/

SMITHearns800permonth

ALLENearns1600permonth

WARDearns1250permonth

JONESearns2975permonth

MARTINearns1250permonth

BLAKEearns2850permonth

CLARKearns2450permonth

SCOTTearns3000permonth

KINGearns5000permonth

TURNERearns1500permonth

ADAMSearns1100permonth

JAMESearns950permonth

FORDearns3000permonth

MILLERearns1300permonth


Notethat,withtheCURSORFORloop,youdonotneedtodeclaretheblockvariablestocapturethecursorcolumns.TheCURSORFORloopindeximplicitlyactsasarecordofthecursortype.Also,youdonotneedtoexplicitlyopenorclosethecursorinthePL/SQLprogram.

ExceptionhandlinginPL/SQLIfaprogramshowsanunusualandunexpectedflowduringruntime,whichmightresultinabnormalterminationoftheprogram,thesituationissaidtobeanexception.SucherrorsmustbetrappedandhandledintheEXCEPTIONsectionofthePL/SQLblock.Theexceptionhandlerscansuppresstheabnormalterminationwithanalternativeandsecuredaction.

Exceptionhandlingisoneoftheimportantstepsofdatabaseprogramming.Unhandledexceptionscanresultinunplannedapplicationoutages,impactbusinesscontinuity,andfrustrateendusers.

Therearetwotypesofexceptions—system-definedanduser-defined.WhiletheOracleDatabaseimplicitlyraisesasystem-definedexception,auser-definedexceptionisexplicitlydeclaredandraisedwithintheprogramunit.

Inaddition,Oracleprovidestwoutilityfunctions,SQLCODEandSQLERRM,toretrievetheerrorcodeandmessageforthemostrecentexception.

System-definedexceptionsAsthenameimplies,system-definedexceptionsaredefinedandmaintainedimplicitlybytheOracleDatabase.TheyaredefinedintheOracleSTANDARDpackage.Wheneveranexceptionoccursinsideaprogram,thedatabasepicksuptheappropriateexceptionfromtheavailablelist.Allsystem-definedexceptionsareassociatedwithanegativeerrorcode(except1to100)andashortname,whichisusedwhilespecifyingtheexceptionhandlers.

Forexample,thefollowingPL/SQLprogramincludesaSELECTstatementtoselectdetailsofemployee8376.ItraisesNO_DATA_FOUNDexceptionbecauseemployeeid8376doesn’texist.

SETSERVEROUTPUTON

/*DeclarethePL/SQLblock*/

DECLARE

L_ENAMEVARCHAR2(100);

L_SALNUMBER;

L_EMPIDNUMBER:=8376;

BEGIN

/*WriteaSELECTstatement*/

SELECTENAME,SAL

INTOL_ENAME,L_SAL

FROMEMP

WHEREEMPNO=L_EMPID;

END;

/

DECLARE

*

ERRORatline1:

ORA-01403:nodatafound

ORA-06512:atline8

LetusrewritetheprecedingPL/SQLblocktoincludeanEXCEPTIONsectionandhandletheNO_DATA_FOUNDexception:


environment*/

SETSERVEROUTPUTON


DECLARE

/*Declarethelocalvariables*/

L_ENAMEVARCHAR2(100);

L_SALNUMBER;

L_EMPIDNUMBER:=8376;

BEGIN

/*SELECTstatementtofetchthenameandsalarydetailsofthe

employee*/

SELECTENAME,SAL

INTOL_ENAME,L_SAL

FROMEMP

WHEREEMPNO=L_EMPID;

EXCEPTION

/*ExceptionHandler*/

WHENNO_DATA_FOUNDTHEN

/*Displayaninformativemessage*/

DBMS_OUTPUT.PUT_LINE('NoEmployeeexistswiththeid'||L_EMPID);

END;

/

NoEmployeeexistswiththeid8376


Thefollowingtablelistssomeofthecommonlyusedsystem-definedexceptionsalongwiththeirshortnameandORAerrorcode:

Error Namedexception Comments(raisedwhen:)

ORA-00001 DUP_VAL_ON_INDEX Duplicatevalueexists

ORA-01001 INVALID_CURSOR Cursorisinvalid

ORA-01012 NOT_LOGGED_ON Userisnotloggedin

ORA-01017 LOGIN_DENIED Systemerroroccurred

ORA-01403 NO_DATA_FOUND Thequeryreturnsnodata

ORA-01422 TOO_MANY_ROWS Asinglerowqueryreturnsmultiplerows

ORA-01476 ZERO_DIVIDE Anattemptwasmadetodivideanumberbyzero

ORA-01722 INVALID_NUMBER Thenumberisinvalid

ORA-06504 ROWTYPE_MISMATCH Mismatchoccurredinrowtype

ORA-06511 CURSOR_ALREADY_OPEN Cursorisalreadyopen

ORA-06531 COLLECTION_IS_NULL WorkingwithNULLcollection

ORA-06532 SUBSCRIPT_OUTSIDE_LIMIT Collectionindexoutofrange

ORA-06533 SUBSCRIPT_BEYOND_COUNT Collectionindexoutofcount

User-definedexceptionsOracleallowsuserstocreatecustomexceptions,specifynames,associateerrorcodes,andraisestatementsinlinewiththeimplementationlogic.IfPL/SQLapplicationsarerequiredtostandardizetheexceptionhandling,notjusttocontroltheabnormalprogramflowbutalsotoaltertheprogramexecutionlogic,youneedtouseuser-definedexceptions.Theuser-definedexceptionsareraisedintheBEGIN..ENDsectionoftheblockusingtheRAISEstatement.

Therearethreewaysofdeclaringuser-definedexceptions:

DeclaretheEXCEPTIONtypevariableinthedeclarationsection.RaiseitexplicitlyintheprogrambodyusingtheRAISEstatement.HandleitintheEXCEPTIONsection.Notethatnoerrorcodeisinvolvedhere.DeclaretheEXCEPTIONvariableandassociateitwithastandarderrornumberusingPRAGMAEXCEPTION_INIT.

NoteAPragmaisadirectivetothecompilertomanipulatethebehavioroftheprogramunitduringcompilation,andnotatthetimeofexecution.

PRAGMAEXCEPTION_INITcanalsobeusedtomapanexceptiontoanon-predefinedexception.ThesearestandarderrorsfromOraclebutnotdefinedasPL/SQLexceptions.

UsetheRAISE_APPLICATION_ERRORtodeclareadedicatederrornumberanderrormessage.

ThefollowingPL/SQLblockdeclaresauser-definedexceptionandraisesitintheprogrambody:


environment*/

SETSERVEROUTPUTON

/*DeclareabindvariableM_DIVISOR*/

VARIABLEM_DIVISORNUMBER;

/*DeclareabindvariableM_DIVIDEND*/

VARIABLEM_DIVIDENDNUMBER;

/*AssignvaluetoM_DIVISORaszero*/

EXEC:M_DIVISOR:=0;


/*AssignvaluetoM_DIVIDENDas10/

EXEC:M_DIVIDEND:=10;



DECLARE

/*Declarethelocalvariablesandinitializewiththebindvariables*/

L_DIVISORNUMBER:=:M_DIVISOR;

L_DIVIDENDNUMBER:=:M_DIVIDEND;

L_QUOTNUMBER;

/*Declareanexceptionvariable*/

NOCASEEXCEPTION;

BEGIN

/*RaisetheexceptionifDivisorisequaltozero*/

IFL_DIVISOR=0THEN

RAISENOCASE;

ENDIF;

L_QUOT:=L_DIVIDEND/L_DIVISOR;

DBMS_OUTPUT.PUT_LINE('Theresult:'||L_QUOT);

EXCEPTION

/*ExceptionhandlerforNOCASEexception*/

WHENNOCASETHEN

DBMS_OUTPUT.PUT_LINE('Divisorcannotbeequaltozero');

END;

/

Divisorcannotbeequaltozero


/*AssignanonzerovaluetoM_DIVISOR*/

EXEC:M_DIVISOR:=2;


/*Re-executetheblock*/

SQL>/

Theresult:5


TheRAISE_APPLICATION_ERRORprocedureTheRAISE_APPLICATION_ERRORisanOracle-suppliedprocedurethatraisesauser-definedexceptionwithacustomexceptionmessage.Theexceptioncanbeoptionallypre-definedinthedeclarativesectionofthePL/SQL.

ThesyntaxfortheRAISE_APPLICATION_ERRORprocedureisasfollows:

RAISE_APPLICATION_ERROR(error_number,error_message[,{TRUE|FALSE}])

Inthissyntax,theerror_numberparameterisamandatoryparameterwiththeerrorvaluerangingbetween20000to20999.error_messageistheuser-definedmessagethatappearsalongwiththeexception.Thelastparameterisanoptionalargumentthatisusedtoaddtheexceptionerrorcodetothecurrenterrorstack.

ThefollowingPL/SQLprogramliststheemployeeswhohavejoinedtheorganizationafterthegivendate.Theprogrammustraiseanexceptionifthedateofjoiningisbeforethegivendate.TheblockusesRAISE_APPLICATION_ERRORtoraisetheexceptionwithanerrorcode20005,andanappropriateerrormessageappearsonthescreen:


environment*/

SETSERVEROUTPUTON


DECLARE

/*Declarethebirthdate*/

L_DOB_MONDATE:='01-DEC-1981';

/*Declareacursortofilteremployeeswhowerehiredonbirthdaymonth*/

CURSORCIS

SELECTempno,ename,hiredate

FROMemp;

BEGIN

FORIINC

LOOP

/*Raiseexception,ifbirthdateislaterthanthehiredate*/

IFi.hiredate<l_dob_monTHEN

RAISE_APPLICATION_ERROR(-20005,'Hiredateearlierthanthegiven

date!!Checkforanotheremployee');

ELSE

DBMS_OUTPUT.PUT_LINE(i.ename||'washiredon'||i.hiredate);

ENDIF;

ENDLOOP;

END;

/

*

ERRORatline1:

ORA-20005:Hiredateearlierthanthegivendate!!Checkforanother

employee

ORA-06512:atline11

Intheprecedingexample,notethattheexceptionnameisnotusedtocreatetheexceptionhandler.JustaftertheexceptionisraisedthroughRAISE_APPLICATION_ERROR,theprogramisterminated.

IfyouwishtohaveaspecificexceptionhandlerfortheexceptionsraisedthroughRAISE_APPLICATION_ERROR,youmustdeclaretheexceptioninthedeclarativesectionandassociatetheerrornumberusingPRAGMAEXCEPTION_INIT.CheckthefollowingPL/SQLprogram:


environment*/

SQL>SETSERVEROUTPUTON


DECLARE

/*Declarethebirthdate*/

L_DOB_MONDATE:='01-DEC-1981';

/*Declaretheexceptionvariable*/

INVALID_EMP_DATESEXCEPTION;

PRAGMAEXCEPTION_INIT(INVALID_EMP_DATES,-20005);

/*Declareacursortofilteremployeeswhowerehiredonbirthdaymonth*/

CURSORCIS

SELECTename,deptno,hiredate

FROMemp;

BEGIN

FORIINC

LOOP

/*Raiseexception,ifbirthdateislaterthanthehiredate*/

IFi.hiredate<l_dob_monTHEN

RAISEINVALID_EMP_DATES;

ELSE

DBMS_OUTPUT.PUT_LINE(i.ename||'washiredon'||i.hiredate);

ENDIF;

ENDLOOP;

EXCEPTION

WHENINVALID_EMP_DATESTHEN

DBMS_OUTPUT.PUT_LINE(SQLERRM||'Hiredateearlierthanthegivendate!!

Checkforanotheremployee');

END;

/

ORA-20005:Hiredateearlierthanthegivendate!!Checkforanother

employee


ExceptionpropagationUntilnow,wehaveseenthat,assoonastheexceptionisraisedintheproceduralsectionofaPL/SQLblock,thecontroljumpstotheexceptionsectionandchoosestheappropriateexceptionhandler.Thenon-existenceoftheexceptionhandlermayleadtotheabnormalterminationoftheprogram.

InthecaseofnestedPL/SQLblocks,iftheexceptionisraisedinaninnerblock,theprogramcontrolflowsdowntotheexceptionsectionoftheinnerblock.Iftheinnerblockhandlestheexception,itisexecutedandtheprogramcontrolreturnstothenextexecutablestatementintheouterblock.

Iftheinnerblockdoesnothandletheexception,theprogramcontrolcontinuestosearchfortheappropriatehandlerandpropagatestotheexceptionsectionoftheouterblock.Yes,theexecutionoftheouterblockisskippedandtheprogramcontrollandsstraightintotheexceptionsection.Theprogramcontrolwillcontinuetopropagatetheunhandledexceptionintheouterblocksuntiltheappropriateoneisfoundandhandled.

Forexample,thefollowingPL/SQLprogramcontainsachildblockwithintheparentblock:

/*Parentblock*/

DECLARE…

BEGIN

/*Outerblockexecutablestatements*/

...

/*ChildBlock*/

DECLARE

...

BEGIN

...

/*Innerblockexecutablestatements*/

...

EXCEPTION

/*Innerblockexceptionhandlers*/

END;

...

/*Outerblockexecutablestatements*/

EXCEPTION

/*Outerblockexceptionhandlers*/

END;

Iftheexceptionisraisedinoneofthe/*Innerblockexecutablestatements*/,thecontrolflowsto/*Innerblockexceptionhandlers*/.Iftheappropriateexceptionhandlerisnotfound,itpropagatesstraighttothe/*Outerblockexceptionhandlers*/andexecutionof/*Outerblockexecutablestatements*/isskipped.

WhenworkingwithnestedPL/SQLblocks,developersmustbecautiouswhilecodingexceptionhandlinglogic.Theexceptionpropagationshouldbethoroughlytestedtobuildfail‑proofapplications.

CreatingstoredproceduresAprocedureisaderivativeofaPL/SQLblockthathasanameandisstoredpersistentlywithinthedatabase.Itistheschemaobjectthatisprimarilyusedtoimplementbusinesslogicontheserverside.Aprocedurepromotesamodularprogrammingtechniquebybreakingdowncomplexlogicintosimpleroutines.

Thekeyfeaturesofstoredproceduresare:

AproceduremustbeinvokedfromtheexecutablesectionofaPL/SQLblockasaproceduralstatement.YoucanalsoexecuteitdirectlyfromSQLPLUSusingtheEXECUTEstatement.NotethataprocedurecannotbecalledfromaSELECTstatement.AprocedurecanoptionallyacceptparametersinIN,OUT,orINOUTmode.Aprocedurecannotreturnavalue.TheonlywayforaproceduretoreturnavalueisthroughOUTparameters,butnotthroughtheRETURN[value]statement.TheRETURNstatementinaprocedureisusedtoskipthefurtherexecutionoftheprogramandexitcontrol.

ThefollowingtabledifferentiatesbetweentheIN,OUT,andINOUTparameters:

IN OUT INOUT

Defaultparametermode Hastobeexplicitlydefined Hastobeexplicitlydefined

Parameter’svalueispassedtotheprogramfromthecallingenvironment

Parameterreturnsavaluebacktothecallingenvironment

Parametermaypassavaluefromthecallingenvironmenttotheprogramorreturnvaluetothecallingenvironment

Parametersarepassedbyreference

Parametersarepassedbyvalue Parametersarepassedbyvalue

Maybeaconstant,literal,orinitializedvariable Uninitializedvariable Initializedvariable

Canholddefaultvalue Defaultvaluecannotbeassigned Defaultvaluecannotbeassigned

Thesyntaxforaprocedureisasfollows:

CREATE[ORREPLACE]PROCEDURE[ProcedureName][ParameterList]

[AUTHIDDEFINER|CURRENT_USER]

IS

[DeclarationStatements]

BEGIN

[ExecutableStatements]

EXCEPTION

[Exceptionhandlers]

END[ProcedureName];

Thefollowingstandaloneprocedureconvertsthecaseoftheinputstringfromlowercasetouppercase:

/*Createaproceduretochangecaseofastring*/

CREATEORREPLACEPROCEDUREP_TO_UPPER(P_STRVARCHAR2)

IS


L_STRVARCHAR2(50);

BEGIN

/*ConvertthecaseusingUPPERfunction*/

L_STR:=UPPER(P_STR);

/*Displaytheoutputwithappropriatemessage*/

DBMS_OUTPUT.PUT_LINE('InputstringinUppercase:'||L_STR);

END;

/

Procedurecreated.

ExecutingaprocedureAprocedurecaneitherbeexecutedfromSQL*PlusoraPL/SQLblock.TheP_TO_UPPERprocedurecanbeexecutedfromSQL*Plus.

ThefollowingcodeshowstheexecutionoftheprocedurefromSQL*Plus(notethattheparameterispassedusingbindvariable):


environment*/


/*Declareasessionvariablefortheinput*/

SQL>VARIABLEM_STRVARCHAR2(50);

/*Assignatestvaluetothesessionvariable*/

SQL>EXECUTE:M_STR:='MyfirstPLSQLprocedure';


/*CalltheprocedureP_TO_UPPER*/

SQL>EXECUTEP_TO_UPPER(:M_STR);

InputstringinUppercase:MYFIRSTPLSQLPROCEDURE


TheP_TO_UPPERprocedurecanbecalledasaproceduralstatementwithinananonymousPL/SQLblock:


environment*/


/*StartaPL/SQLblock*/

SQL>BEGIN

/*CalltheP_TO_UPPERprocedure*/

P_TO_UPPER('MyfirstPLSQLprocedure');

END;

/

InputstringinUppercase:MYFIRSTPLSQLPROCEDURE


FunctionsSimilartoastoredprocedure,afunctionisanamedderivativeofaPL/SQLblockthatisphysicallystoredwithintheOracledatabaseschema.

Thekeyfeaturesofstoredfunctionsareasfollows:

Afunctioncanacceptparametersinallthreemodes(IN,OUT,andINOUT)andmandatorilyreturnsavalue.FunctionscanbecalledinSQLstatements(SELECTandDMLs).SuchfunctionsmustacceptonlyINparametersofvalidSQLtypes.Alternatively,afunctioncanalsobeinvokedfromSELECTstatementsifthefunctionbodyobeysthedatabasepurityrules.IfthefunctioniscalledfromanSQLstatement,itsreturntypeshouldbeavalidSQLdatatype.IfthefunctionisinvokedfromPL/SQL,thereturntypeshouldbeavalidPL/SQLtype.

NoteStartingfromOracleDatabase12c,PL/SQL—onlydatatypescancrossthePL/SQLtoSQLinterface.APL/SQLanonymousblockcaninvokeaPL/SQLsubprogramwithparametersofBOOLEANorapackagedcollectiontype.

Thesyntaxforafunctionisasfollows:

CREATE[ORREPLACE]FUNCTION[FunctionName][ParameterList]

RETURN[Datatype]

[AUTHIDDEFINER|CURRENT_USER]

[DETERMINISTIC|PARALLEL_ENABLED|PIPELINED]

[RESULT_CACHE[RELIES_ON(tablename)]]

IS

[DeclarationStatements]

BEGIN

[ExecutableStatements]

RETURN[Value]

EXCEPTION

[Exceptionhandlers]

END[FunctionName];

Letuscreateastandalonefunction,F_GET_DOUBLE,whichacceptsanumericparameterandreturnsitsdouble:

/*CreatethefunctionF_GET_DOUBLE*/

CREATEORREPLACEFUNCTIONF_GET_DOUBLE(P_NUMNUMBER)

RETURNNUMBER/*Specifythereturndatatype*/

IS

/*Declarethelocalvariable*/

L_NUMNUMBER;

BEGIN

/*Calculatethedoubleofthegivennumber*/

L_NUM:=P_NUM*2;

/*Returnthecalculatedvalue*/

RETURNL_NUM;

END;

/

Functioncreated.

Functions–executionmethodsFunctionscaneitherbecalledfromaSQL*PlusenvironmentorinvokedfromaPL/SQLprogramasaproceduralstatement.

ThefunctionF_GET_DOUBLEcanbeexecutedintheSQL*Pluscommandpromptasfollows.Asthefunctionreturnsanoutput,youmustdeclareasessionvariableandcapturethefunctionresultinthevariable.


environment*/

SETSERVEROUTPUTON

/*DeclareasessionvariableM_NUMtoholdthefunctionoutput*/

VARIABLEM_NUMNUMBER;

/*Functionisexecutedandoutputisassignedtothesessionvariable*/

EXECUTE:M_NUM:=F_GET_DOUBLE(10);


/*PrintthesessionvariableM_NUM*/

PRINTM_NUM

M_NUM

----------

20

TheF_GET_DOUBLEfunctioncanbecalledfromananonymousblockorastandalonesubprogram.


environment*/

SETSERVEROUTPUTON

DECLARE

M_NUMNUMBER;

BEGIN

M_NUM:=F_GET_DOUBLE(10);

DBMS_OUTPUT.PUT_LINE('Doubledtheinputvalueas:'||M_NUM);

END;

/

Doubledtheinputvalueas:20


RestrictionsoncallingfunctionsfromSQLexpressionsUnlikeprocedures,astoredfunctioncanbecalledfromaSELECTstatement,provideditdoesnotviolatethedatabasepuritylevels.Therulesareasfollows:

AfunctioncalledfromaSELECTstatementcannotcontainDMLstatementsAfunctioncalledfromanUPDATEorDELETEstatementonatablecannotquery(SELECT)orperformtransactions(DMLs)onthesametableAfunctioncalledfromanSQLexpressioncannotcontainTCL(COMMITorROLLBACK)commandsorDDL(CREATEorALTER)commands

TheF_GET_DOUBLEfunctioncaneasilybeembeddedwithinaSELECTstatementasitrespectsalltheprecedingrules:

/*InvokethefunctionF_GET_DOUBLEfromSELECTstatement*/

SQL>SELECTF_GET_DOUBLE(10)FROMDUAL;

F_GET_DOUBLE(10)

----------------

20

NoteIntheOracleDatabase,DUALisatableownedbytheSYSuser,whichhasasinglerowandasinglecolumn,DUMMY,ofVARCHAR2(1)type.ItwasfirstdesignedbyCharlesWeisswhileworkingwithinternalviewstoduplicatearow.TheDUALtableiscreatedbydefaultduringthecreationofthedatadictionarywithasinglerowwhosevalueisX.Alldatabaseusers,otherthanSYS,useitspublicsynonymtoselectthevalueofpseudocolumnssuchasUSER,SYSDATE,NEXTVAL,orCURRVAL.Oracle10gconsiderablyimprovedtheperformanceimplicationsoftheDUALtablethroughafastdual-accessmechanism.

APL/SQLpackageAPL/SQLpackageencapsulatesmultiplePL/SQLconstructsunderasingleunit.ThePL/SQLconstructscanbesubprograms,cursors,variables,andexceptions.Asaschemaobject,aPL/SQLpackagedemonstratestheprinciplesoflogichiding,encapsulation,andsubprogramoverloading.

NoteStandalonesubprogramscannotbeoverloaded.Onlypackagedsubprogramscanbeoverloadedbytheirsignatures.

Thefollowingdiagramshowstheadvantagesofapackage:

Apackagehastwocomponents—thepackagespecificationandpackagebody.Whilethepackagespecificationcontainstheprototypeofpublicconstructs,thepackagebodycontainsthedefinitionofpublicaswellasprivate(local)constructs.

Thecharacteristicsofthepackagespecificationareasfollows:

Itisthemandatorycomponentofthepackage.Apackagecannotexistwithoutitsspecification.Itcontainstheprototypesofpublicconstructs.Theprototypeisaforwarddeclarationoftheconstructsthatincludesthedeclaration,headerspecificationandsignatureinformationterminatedbyasemicolon.Thesubprogramsconstructs,onceprototyped,shouldbedefinedinthepackagebodysection.Thepackagespecificationcannotcontainanexecutablesection.Thesememberconstructsarevisiblewithinandoutsidethepackage.Theycanbeinvokedfromoutsidethepackagebytheprivilegedusers.

NoteThepublicconstructsofapackageareaccessedas[PACKAGENAME].[CONSTRUCT].

ValidpackageconstructscanbePL/SQLtypes,variables,exceptions,procedures,andfunctions.Ifthepackagespecificationcontainsvariables,theyareimplicitlyinitializedtoNULLbyOracle

Thecharacteristicsofthepackagebodyareasfollows:

Thepackagebodycontainsthedefinitionofthesubprogramsthatweredeclaredinthepackagespecification.Thepackagebodycanoptionallycontainlocalconstructs.Theaccessibilityofthelocalconstructsislimitedtothepackagebodyonly.Thepackagebodyisanoptionalcomponent;apackagecanexistinadatabaseschemawithoutitspackagebody.

Thesyntaxforcreatingapackageisasfollows:

CREATE[ORREPLACE]PACKAGE[NAME]IS

[PRAGMA]

[PUBLICCONSTRUCTS]

END;

CREATE[ORREPLACE]PACKAGEBODY[NAME]IS

[LOCALCONSTRUCTS]

[SUBPROGRAMDEFINITION]

[BEGIN]

END;

NotetheoptionalBEGINsectioninthepackagebody.Itisoptional,butgetsexecutedonlythefirsttimethepackageisreferenced.Itisusedtoinitializeglobalvariables.

Apackagecanbecompiledwithitsspecificationcomponentalone.Insuchcases,packagedprogramunitscannotbeinvokedastheirexecutablelogichasnotbeendefinedyet.

Thecompilationofapackagewithaspecificationandbodyensurestheconcurrencybetweentheprogramunitsprototypedinthespecificationandtheprogramunitsdefinedinthepackagebody.Allpackagedprogramunitsarecompiledinasinglepackagecompilation.Ifapackageiscompiledwitherrors,itiscreatedasaninvalidobjectinthedatabaseschema.YoucanquerytheSTATUScolumntocheckthecurrentstatusofanobjectintheUSER_OBJECTS,ALL_OBJECTS,orDBA_OBJECTSdictionaryviews.

OracleDatabase12cenhancementstoPL/SQLsubprogramsOracleDatabaseRelease12cincludesanumberofPL/SQLfeatureenhancements.TheseenhancementsarefocusedonimprovingtheusabilityofPL/SQLasalanguage.Althoughthenextchapterwilldiscussmanymorenewfeaturesindetail,itisworthwhiletomentionafewofthemthatareexclusivelyrelatedtoOraclePL/SQLsubprograms.

DefiningPL/SQLsubprogramsintheSELECTstatement:AlthoughPL/SQLallowstheinvokingofafunctionfromtheSELECTstatement,thecontextswitchfromSQLtothePL/SQLenginedegradedtheperformance.Oracle12callowscreatingPL/SQLunitsintheWITHclauseofasubqueryandusingitintheSELECTstatement.ThenewapproachtocallingfunctionsinSQLstatementsenhancestheperformanceasthereisnocontextswitchingacrosstheengines.Inaddition,thesefunctionsarenotstoredinthedatabaseschema.Grantingrolestoprogramunits:OneofthechallengesinPL/SQLbeforeOracle12cwasthataprogramunithadtobecreatedwithdefinersrights,ifitwasintendedtobeexecutedbyallusers.Auserwithalowersetofprivilegescouldperformtheunauthorizedchanges.WithOracle12c,grantingrolestoPL/SQLprogramunitsaddsalevelsofsafety.Youcannowcreateprogramunitswithinvoker’srightsandcontroltheprivileges,whicharerequiredtoruntheprogram,througharole.ProtectingPL/SQLunitaccessthroughtheACCESSIBLEBYclause:WithOracle12c,youcanrestrictaccesstoaPL/SQLunitbyunauthorizedprograms.Asubprogram(aprocedure,functionorapackage)canoptionallyincludeanACCESSIBLEBYclausetodefineawhitelistofPL/SQLprogramunitsthatcaninvokeit.

ManagingdatabasedependenciesPL/SQLprogramunits,aswellasotherdatabaseobjectssuchasviews,mayrefertootherdatabaseobjectsintheirproceduralsection.Thecallingprogramunitissaidtobedependentonthecalledprogramunits(knownasreferencedobjects).IfEMPandDEPTarethebasetablesusedincreatingaviewV_EMP_REP,thentheviewisdependentonEMPandDEPT.

NoteAsequencecanalwaysbeareferencedobject.Apackagebodyisalwaysadependentobject.

Databasedependencycanbeclassifiedasdirectorindirect.Considerthreeobjects—P,M,andN.IfobjectPreferencesobjectMandobjectMreferencesobjectN,thenPisdirectlydependentonMandindirectlydependentonN.

DisplayingthedirectandindirectdependenciesThedependencymatrixisautomaticallygeneratedandmaintainedwithintheOracleDatabase.Thestatusofanobjectisthebasisofdependencyamongtheobjects.ThestatusofanobjectcanbequeriedfromtheUSER_OBJECTS(orALL_OBJECTSorDBA_OBJECTS)dictionaryview.ThefollowingqueryqueriesthestatusofthefunctionF_GET_DOUBLE:

/*CheckthestatusofthefunctionF_GET_DOUBLE*/

SELECTstatus

FROMuser_objects

WHEREobject_name='F_GET_DOUBLE'

/

STATUS

-------

VALID

ThesystemviewsDEPTREEandIDEPTREEcapturethenecessaryinformationaboutthedirectandindirectdependencies.Databaseadministratorscancreatetheviewsbyrunningthescript$ORACLE_HOME\RDBMS\ADMIN\utldtree.sql.

Theexecutionstepsforthescriptareasfollows:

1. LoginasSYSDBAinSQLDeveloperorSQL*Plus.2. Copythecompletepathandscriptname(prefixedwith@).3. Executethescript(withF9).4. QuerytheDEPTREEandIDEPTREEviewstoverifytheircreation.

ThescriptcreatestheDEPTREE_TEMPTABtableandtheDEPTREE_FILLprocedure.TheDEPTREE_FILLprocedurecanbeexecutedtopopulatethedependencydetailsofanobject.

/*PopulatethedependencymatrixforthefunctionF_GET_DOUBLE*/

SQL>EXECDEPTREE_FILL('FUNCTION','SCOTT','F_GET_DOUBLE');


NotethatthefirstparameteroftheDEPTREE_FILLprocedureistheobjecttype,thesecondistheowner,andthethirdistheobjectname.

TheDEPTREEandIDEPTREEviewscannowbequeriedtoviewthedependencyinformation.

DependencymetadataOracleprovidesthedatadictionaryviews(USER_DEPENDENCIES,ALL_DEPENDENCIES,andDBA_DEPENDENCIES)toviewthecompletedependencymetricssharedbyanobject.Besidesthedependentobject’slist,italsolistsitsreferencingobjectnameandowner.

ThefollowingscreenshotshowsthestructureofthedictionaryviewDBA_DEPENDENCIES:

DependencyissuesandenhancementsInlinewiththeconventionaldependencyphenomenon,thestatusvalidityofthedependentobjectdependsuponthestatusofthereferencedobject.So,ifthedefinitionofthereferencedobjectisaltered,thedependentobjectismarkedINVALIDintheUSER_OBJECTSview.Althoughobjectrecompilationcaneasilysolvetheproblem,theobjectinvalidationsmayimpacttheapplicationflow.

Oracle11gintroducedFineGrainedDependencyTracking(FGD)tomodifythedependencyprincipleasfollows.Ifthealterationinthereferencedobjectdoesnotaffectthedependentobject,thedependentobjectwillremainintheVALIDstate.Forinstance,ifaviewiscreatedwithafixedsetofcolumnsofatableandthetableisalteredtoaddanewcolumn,theviewwillremaininaVALIDstate.

ReviewingOracle-suppliedpackagesOracle-suppliedpackagesexistasprebuiltprogramsinthedatabaseaswrappercode.Thesepackagesnotonlyhelpdatabasedevelopersworkonextendedfunctionalitiesbutalsoreducewritingextensiveandcomplexcode.TheuseoftheOracle-suppliedAPIisalwaysrecommendedasitimprovescodestandardization.

Thescriptsforthesepackagesareavailableinthe$ORACLE_HOME\RDBMS\ADMIN\folder.Allpackagesresideonthedatabaseserver.Publicsynonymsareavailable(orcanbecreatedtoo)forthesepackagessothatthepackagesareaccessibletothedatabaseusers.Oracle12caddsmultiplepackagestotheOracle-suppliedPL/SQLpackagelist.ThelatestadditionsprovidePL/SQLinterfacesforthenewfunctionalitiesthathavebeenaddedtothedatabaserelease.

SomeoftheimportantOracle-suppliedpackagesarelistedasfollows:

DBMS_ALERT:Thispackageisusedforthenotificationofdatabaseevents.DBMS_LOCK:Thispackageisusedformanaginglockoperations(lock,conversion,andrelease)inPL/SQLapplications.DBMS_SESSION:ThispackageisusedtosetsessionlevelpreferencesfromPL/SQLprograms(similartoALTERSESSION).DBMS_OUTPUT:Thispackageisoneofthemostfrequentlyusedbuilt-insforbufferingdatamessagesanddisplayingdebuginformation.DBMS_HTTP:ThispackageisusedforHTTPcallouts.UTL_FILE:Thispackageisusedforreading,writing,andperformingotherfileoperationsontheserver.UTL_MAIL:Thispackageisusedtocomposeandsendmails.DBMS_SCHEDULER:Thispackageisusedforschedulingexecutionofstoredproceduresatagiventime.DBMS_PARALLEL_EXECUTE:Thispackagecanbeusedtoexecuteauser-definedtaskinparallel.IfthePL/SQLblockisrunningalargeupdateonatable,thepackagecanbeusedtoenabletheparallelexecutionofthetaskbysplittingitintochunks.DBMS_PRIVILEGE_CAPTURE:ThispackageisintroducedinOracleDatabase12ctosetapolicyinordertocapturetheusageofprivileges(objectandsystem)inrespecttousers.Ithelpsincontrollingexcessprivilegesforusers.DBMS_REDACT:ThispackageisintroducedinOracleDatabase12ctocreateredactionpolicies,inordertomaskdatabasedonuserauthorization.DBMS_RESOURCE_MANAGER:Thispackageisusedtocreateconsumergroups,directives,andresourcemanagerplansforcontainersaswellasapluggabledatabase.Theresourcemanagerplandeterminestheresourcesallocatedtoapluggabledatabase,aschema,oratask.DBMS_DATAPUMP:Thispackageisusedtomovedata,metadata,orbothfromonedatabasetoanother.Thesourceandtargetdatabasescanbeondifferentplatforms.DBMS_PDB:ThispackageisintroducedinOracleDatabase12ctogenerateoranalyzetheintegrationpropertiesofapluggabledatabaseforunplug/plugoperations.

DBMS_SQL:ThispackageenablesdynamicSQLinPL/SQL.YoucanrunDMLorDDLstatementsusingDBMS_SQLfromaPL/SQLblock.DBMS_REDEFINITION:Thispackageisusedtoperformonlineredefinitiontasksfortables.DBMS_UTILITY:Thispackageisusedtoaccomplishmanyutilityoperationssuchasanalyzeobject,compileschema,getdependency,resolveagivenname,validatedatabaseobjects,formatcallanderrorstack,expandSQLtext,andretrievecurrentdatabaseversion.

Basedontheobjectivetobeachieved,thepackagescanbecategorizedasfollows:

Standardapplicationdevelopment:ManyoftheDBMSpackagesprovideanapplicationinterfacefordatabasefeatures.Forexample,DBMS_REDACTprovidesaninterfacetocreateandmanageredactionpolicies.Similarly,DBMS_UTILITYprovidessubprogramstoretrieveinstanceordatabaseinformation,callstacksanderrorstacks,andanalyzeandvalidateobjects.TheDBMS_OUTPUTpackageisoneofthepackagesmostfrequentlyusedtodisplaytextmessages.Itcanbeefficientlyusedfortracinganddebuggingpurposes.AccessingandwritingoperatingsystemfileswasmadepossiblethroughUTL_FILE.Generalusageandapplicationadministration:Oraclehasmanypackagesformonitoringapplicationsandusers.Statisticsgeneration,loadhistory,andspacemanagementarethekeyobjectivesaccomplishedbythesepackages.DBMS_UTILITYcomprisessubprogramsforgeneralusage.Internalsupportpackages:Oraclemaintainsthesepackagesforitsownuse.Transactionprocessingpackages:Oracleprovidesutilitypackagesthatenablethemonitoringoftransactionstages.Thoughtheyarerarelyused,theycanefficientlyensuretransparentandsmoothtransactions.Forexample,DBMS_TRANSACTIONisusedtoaccessSQLtransactionsfromstoredsubprograms.DBMS_PARALLEL_EXECUTEexecutesalargeupdateinparallelbysplittingitintosmalltasks.

OracleSQLDeveloperOracleSQLDeveloperisaGraphicalUserInterface(GUI)integrateddevelopmentenvironmentfromOracleCorporation.OracleSQLDeveloperisafreetoolthatsimplifiesPL/SQLcodedevelopment,thedatabasedesign,andmodelingandadministrationforstandaloneandclouddeployments.Thistoolenhancestheuser’sexperiencebymaximizingproductivityandextensibility.

SQLDeveloperisaJava-basedcross-platformtoolthatcanrunonLinux,Windows,andMacOSX.

OracleSQLDevelopersupportsOracleDatabaseversions10g,11g,and12c.WithOracleDatabase12cMultitenantarchitecture,SQLDeveloperextendsfullsupportforvariousmultitenantoperations.InadditiontothesupportforOracleDatabases,thetoolalsoallowsuserstoconnecttonon-OracleDatabasesincludingMySQL,MicrosoftSQLServer,MicrosoftAccess,Sybase,andTeradata.Theextensibleframeworkenablesuserstodevelopcustomextensionsinordertoaddressspecificrequirements.

SQLDeveloperwasfirstreleasedinMarch,2006.TheinitialreleaseofSQLDeveloperincludedbasicfeaturessuchasaschemabrowser,anSQLworksheettorunSQLandinvokeSQLscripts,aPL/SQLeditor,codedebugging,andrunningbasicreports.Sincethen,thetoolhasgrownimmenselyandmaturedovertheyears.Atthetimeofwriting,thelatestreleaseofSQLDeveloperis4.1.

OracleSQLDeveloperforDBA,Developers,andApplicationArchitectsOracleSQLDeveloperprovidespowerfulfeaturesandinterfacesforcodedevelopment,administrativeactivities,anddatamodeling.ItoffersricheditorsfordeveloperswhoworkwithSQL,PL/SQL,andstoredprogramunits.SQLDevelopercanrunSQLqueries,monitorperformancethroughexecutionplansandSQLtuning,andpreparescripts.DatabasedeveloperscanbuildPL/SQLapplications,debugthem,andperformrun-timetesting.

WithSQLDeveloper3.0,theDBApanelinthetooladdedthefunctionalitytoperformcommonDBAtasksandactivities.Thenewfeatureadditionssuchasthedataminer,datamodeler,databasenavigator,andDBMSschedulerprovidearangeofadministrativefunctionalitiesinthetool.Databaseadministratorscanperformcoreadministrationtaskssuchasexport/importthroughdatapump,RMAN,userandrolemanagement,andresourcemanagement.SQLDeveloperintegratesseamlesslywithOracleAPEX,therebyallowingAPEXdeveloperstobrowse,deploy,andexportapplications.

Withthemostrecentversion,moreDBAactivitieshavebeenincorporatedtomakeitmorefeature-richandcomplete.

Fordatabasearchitects,SQLDeveloperoffersadatamodelingsolutionwithSQLDeveloperDataModeler(SDDM).TheSDDMenablesarchitectstocreatedataflowdiagrams,designversioningviasubversion,importdesignerrepositories,andmostimportantlyperformlogical,relational,andphysicaldatamodeling.

SQLDeveloper4.0WiththereleaseofOracleSQLDeveloper4.0andonwards,thetoolfollowsOracle’sdatamanagementstrategybysupportingOracleDatabase12cMultitenantoption,clouddeployments,OracleNoSQLandJSON.Inaddition,itincludesabrandnewcommandlineinterfaceutilitytoenhanceuserexperience.WithnativesupportforOracleRestDataServicesinOracleDatabase12c,WebapplicationdeveloperscanworkwithSQLDevelopertocreateandalterservices.DatabaseadministratorscannowrunASH,AWR,andADDMreportsfromtheperformancepageintheDBApanel.SQLDeveloper4.0’snewfeaturescanbesummarizedasfollows:

SupportforOracleDatabase12cMultitenantarchitectureSupportforOracleNoSQLDatabaseSupportfordatabaseproductssuchasTimesTen,DataMiner,XMLDB,andSpatialandGraphsSupportforJava7QueryingJSONdatainrelationalformatNewinstanceviewerenablesthemonitoringofwaitevents,storage,logswitches,anddatabaseprocesses

Chapter12,WorkingwithOracleSQLDeveloper,focusesonvariousfeaturesoftheOracleSQLDevelopertool.

SummaryOvertheyears,PL/SQLhasmaturedagreatdealandhasproducedavastlibraryofobjects,features,andstandards.ThischapterfocusedongivingaquicksummaryofPL/SQLprogramming.Itassumedreaderswerefamiliarwithdatabaseprogrammingconceptsandprovidedenoughsubstancetogetthemreadyfortheforthcomingchapters.ItwouldhavebeenatoughcalltobuildaglossaryofPL/SQLobjectsinasinglechapter.

WestartedwithanoverviewofPL/SQLfundamentals,blockstructure,andexceptionhandling.Additionally,thischapterthrewlightoncursorhandlinginPL/SQL,theCURSORFORloop,andschemaobjectssuchasprocedures,functions,andpackages.Inforthcomingchapters,wewillfocusonthekeyfacultiesofthePL/SQLlanguageaswellasOracleDatabase12cfeatures.

PracticeexerciseWhichofthefollowingfeaturesarenotavailableinSQLDeveloper?

1. Querybuilder.2. Databaseexportandimport.3. Databasebackupandrecoveryfunctions.4. CodeSubversionrepository.

ForafunctiontobecalledfromaSQLexpression,whichofthefollowingconditionsshoulditobey?

1. AfunctionintheSELECTstatementshouldnotcontainDMLstatements.2. Thefunctionshouldreturnavalue.3. AfunctionintheUPDATEorDELETEstatementshouldnotquerythesametable.4. AfunctioncalledfromaSQLexpressioncannotcontainTCL(COMMITor

ROLLBACK)commandsorDDL(CREATEorALTER)commands.

ThefollowingqueryisexecutedintheSCOTTschema:

SELECTNAME,referenced_owner,referenced_name

FROMall_dependencies

WHEREowner=USER

ANDreferenced_typeIN('TABLE','VIEW')

ANDreferenced_ownerIN('SYS')

ORDERBYowner,NAME,referenced_owner,referenced_name;

Whichstatementistrueabouttheoutputofthisquery?

1. Itdisplaystheschemaobjects,createdbytheuserORADEV,thatuseatableorviewownedbySYS.

2. AnexceptionoccursasuserSCOTThasinsufficientprivilegestoaccessALL_DEPENDENCIESview.

3. ItdisplaysallPL/SQLcodeobjectsthatreferenceatableorviewdirectlyforalltheusersinthedatabase.

4. ItdisplaysonlythosePL/SQLcodeobjectscreatedbytheuserOEthatreferenceatableorviewcreatedbytheuserSYS.

WhichofthefollowingistrueaboutPL/SQLblocks?

1. ExceptionisamandatorysectionwithoutwhichananonymousPL/SQLblockfailstocompile.

2. BindvariablescannotbereferredinsideaPL/SQLblock.3. Thescopeandvisibilityofthevariablesdeclaredinthedeclarativesectionof

theblockarewithinthecurrentblockonly.4. TheRAISE_APPLICATION_ERRORproceduremapsapredefinederrormessagetoa

customizederrorcode.

Fromthefollowingoptions,identifythewaysofdefiningexceptions:

1. DeclareanEXCEPTIONvariableandraiseitusingtheRAISEstatement.2. UsePRAGMAEXCEPTION_INITtoassociateacustomizedexceptionmessagetoa

pre-definedoracleerrornumber.3. DeclareanEXCEPTIONvariableanduseitinRAISE_APPLICATION_ERROR.4. UseRAISE_APPLICATION_ERRORtocreateadynamicexceptionatanystage

withintheexecutableorexceptionsectionofaPL/SQLblock.

Choosethedifferencesbetweenproceduresandfunctions:

1. Afunctionmustmandatorilyreturnavalue,whileaproceduremayormaynot.2. AfunctioncanbecalledfromaSQLquery,whileaprocedurecanneverbe

invokedfromSQL.3. Afunctioncanacceptparameterspassedbyavalue,whileaprocedurecan

acceptparameterspassedbyreferenceonly.4. Astandalonefunctioncanbeoverloadedbutaprocedurecannot.

Examinethevaluesofthecursorattributeforthefollowingqueryandpicktheattributewiththewrongvalue:

BEGIN

…

SELECTENAME,SAL

INTOL_ENAME,L_SAL

FROMEMPLOYEES

WHEREEMPID=7900;

…

END;

1. SQL%ROWCOUNT=12. SQL%ISOPEN=FALSE3. SQL%FOUND=FALSE4. SQL%NOTFOUND=FALSE

Chapter2.Oracle12cSQLandPL/SQLNewFeaturesOraclereleasedOracleDatabase12cinJuly2013.Fromatechnologystandpoint,itwasanimportantproductreleaseasthefocuswasconsolidationofdatabasesonpublicandprivatecloudinfrastructures.OracleDatabase12cintroducesthenewMultitenantarchitecturethatallowsmultipledatabasestorunasatenantwithinasingledatabase.Thenewdesignassurestenantisolationandsecurity,andenhancesmanageabilityofconsolidateddatabases,OracleDatabase12cprovidesmorethan500newfeaturesincludingmultitenantarchitectureandmanyothersrelatedtosecurity,highavailability,andperformance.Thechaptercoversthekeyfeaturesintroducedinthelatestproductrelease.

OracleDatabase12chasmadeconsiderableimprovementstotheSQLandPL/SQLlanguages.ThelanguageenhancementsinOracleDatabase12cfocusonsupportforANSISQLstandards,effortlesscodewritingandmigrationfromnon-OracletoOraclecompliantcode.ThischapterdiscussesmanysuchenhancementsandfeaturesofOracleDatabase12c.

Theoutlineofthechapterisasfollows:

TheMultitenantarchitectureSQLnewfeaturesPL/SQLnewfeaturesOracleDatabase12cIn-Memoryoption

DatabaseconsolidationandthenewMultitenantarchitectureConsolidationisthekeyenablerformovingdatabasestoon-cloudmodels.Anefficientconsolidationstrategycanprovideelasticsharingofresourcesandmaximizeresourceutilizationinaconsolidatedstack.Adatabasehostedonapublicorprivatecloudmustguaranteetenantisolationandsecurity.Inadditiontotheelementaryrequirementsofclouddeployments,databaseprovisioningonthecloudshouldbequickandeasy.

OracleDatabase12cintroducesamultitenantarchitecturethatmeetsthechallengesofclouddeployments.Thenewtenant-basedarchitectureallowsoneormoreapplicationdatabases(knownaspluggabledatabases)torunwithinasingledatabase(knownasthecontainerdatabase).Eachpluggabledatabaseiscompletelyshieldedfromallotherpluggabledatabasesrunningwithinthesamecontainerdatabase.Thearchitectureprovidesauniquemechanismtosegregatethesystemandapplicationmetadataatthecontainerandpluggablelevelrespectively.Inasingle-tenantarchitecture,arootcontainercanhavejustonepluggabledatabase.Inamultitenantarchitecture,arootcontainercanhavemorethanonepluggabledatabase.Whilesingle-tenantisfreeofcostandavailableinOracleDatabaseStandardEdition,multitenantcanbelicensedinOracleDatabaseEnterpriseEditiononly.

StartingwithOracleDatabase12.1.0.2,thenon-tenantorstandalonearchitectureofOracleDatabaseisdeprecatedwhichmeansthatitwillnotbefurtherenhanced.

Letusgetfamiliarizedwiththetermsofthenewworld—thecontainerandpluggabledatabases.

AnOracle12ccontainerdatabase(CDB)providestheinstancethatcanbesharedbymultipledatabases.ACDBinstancehasthememoryandasetofbackgroundprocesses.Fromtheserversubsystem,thecontainerdatabaseistheonlydatabasevisible.

Apluggabledatabase(PDB)issimilartoapre12cdatabasethatservesasanapplicationdatabasebackend.Apluggabledatabasecontainstheapplicationtablespaces.

ThefollowingdiagramshowstheOracleDatabase12cmultitenantarchitecture:

Acontainerdatabasemaycontainoneormorepluggabledatabasecontainers.Withreferencetotheprecedingarchitecture,letusdrillintothespecificsofnewcomponents.

Acontainerdatabase(CDB)consistsofonerootcontainer(knownasCDB$ROOT),oneseedpluggabledatabase(knownasPDB$SEED),andmultiplepluggabledatabases.Similartothepreviousreleases,acontainerdatabasehasaninstanceandsetoffiles.Thedatabaseinstanceisofthecontainer,whichmeansthattheSystemGlobalArea(SGA)iscommonforallthepluggabledatabases.Also,thereisasinglecopyofbackgroundprocessesatthecontainerinstancelevelonly,andnotreplicatedforeachPDB.

Apluggabledatabaseisadatabasethatstorestheapplicationdata.AsofOracleDatabase12cRelease1,amultitenantdatabasecanhaveamaximumof252pluggabledatabases.APDBserviceiscreatedatthetimeofprovisioningthatrunswithintheCDBserviceandgetsauto-registeredwiththeCDBlistener.SinceaPDBrunsasasecuredservicewithinthecontainerdatabaseadministrationservice,itcannotbeauthenticatedbytheserveroperatingsystem.However,youcancreateauser-definedserviceusingDBMS_SERVICEforOSauthenticationandTNSconnection.

Theredologsandarchivelogsareatthecontainerlevel.Everytimeapluggabledatabasehastomakearedoentry,therequestistaggedwiththePDBidentity.Theidentityinthiscaseisnothingbutthecontaineridentifier(CON_ID).Eachcontainerinacontainerdatabaseisassignedauniquecontainerid.Theroothasthecontainerid1;theseedPDBhas2andeachpluggabledatabaseisassignedacontaineridinasequentialfashion.Thecontaineridisquiteasignificantelementasthecommonredoislogicallyvirtualizedbyannotatingeachandeveryentrywiththecontainerid.AllthedictionaryviewsandmetadataviewshaveanadditionalcolumnCON_IDtoidentifythecontainertowhichtheinformationbelongs.

Thecontrolfileandserverparameterfileareattherootcontainerlevel.Startingwith

Oracle12c,therearetwocategoriesofparameters—CDBmodifiableandPDBmodifiable.TheV$PARAMETERdictionaryviewhasanadditionalcolumnISPDB_MODIFIABLE.ThevalueofthecolumnisNforCDB-modifiableandYforPDB-modifiableparameters.

TheSYSTEMandSYSAUXtablespacesattherootcontainerlevelstorethesystemmetadatathatisspecificjusttotheOracleDatabase.TheapplicationmetadataforeachpluggabledatabaseisstoredineachPDB’srespectiveSYSTEMandSYSAUXtablespaces.TheUNDOtablespaceisattherootcontainerlevel.Onceagain,similartoredo,eachundoentryistaggedwiththecontaineridentifierorCON_ID.Withoneundofortheentirecontainer,youmightbeinterestedinevaluatingtheperformanceimplicationsofthesystem.Well,undomanagementinmultitenantconsolidationisnottoodifferentfromschemaconsolidation.Theredoandundoentriesareindexedbythecontainerids,thusspeedinguptheconcurrentrecordaccessforaspecificPDB.

AlthoughthemultitenantarchitectureshowstheTEMPtablespaceatthecontainerlevel,butitcanbecreatedforeachofthepluggabledatabasetoo.Userscancreatetablespaceswithinthepluggabledatabasesasusual,wheneverrequired.

TheOracleDatabase12cMultitenantarchitecture–featuresHavingmentionedthechallengesofconsolidationandclouddeployments,letustakealookatthecapabilitiesenabledbythemultitenantarchitecture.

MultitenantforConsolidationInthepast,enterpriseshavebeenfollowingmultipleapproachestoconsolidatedatabasestoachievetenantisolationandmanageability.Youcouldhaveanenormousphysicalserverandthenextractvirtualizedhomesforeachapplication.Thevirtualizedhomeistheapplication’sworldofoperationandsharestheserversubsystem.Howevertheoverheadofmanagingtheheterogeneouspiecescanbeapotentialpainpoint.Theconsolidationdensityislimitedbythefactthatthememoryallocatedtoavirtualizedhomeremainsintactwhetherornotitisgettingused.

Youcancreatemultipledatabasesonaserverforeachapplication.Anaggregationofdatabasesispossibleuntiltheservermemoryisexhausted.Keepinmindthateachdatabaseinstancecreatesit’sowncopyofbackgroundprocesses,whichholdstheCPUcycles,thusreducingtheconsolidationdensity.

OneofthemostefficientapproachesbeforeOracle12cwastoadoptschema-basedconsolidation.Youcanachievethehighestconsolidationdensityasmultipleschemasarepartofasingledatabase.Thedownsideofschema-basedconsolidationisthattenantisolationwasnotguaranteed,whilesecurityandmanageabilitywereabigconcern.

ThemultitenantapproachinOracleDatabase12callowstheeffectivesharingofserverresources,theoperatingsystem,andeventhedatabase.Theadvancedsharingofresourcesmakesitsuitabletoimplementanddeployonthecloud.Itguaranteesthetenantisolationaseachpluggabledatabaseappearsremotetootherpluggabledatabasessharingthesamecontainer.AcommonSGAandasinglesetofbackgroundprocessesoptimallyutilizetheservermemory,thusmaximizingconsolidation.ManagementcapabilitiesaddvaluetothenewarchitectureinOracle12c.

Plug/unplugApluggabledatabasecanbeunpluggedfromthecurrentcontainerandpluggedintoanothercompatiblecontainer.DatamobilityacrossthecontainersbecomeseasierandquickerasyoujusthavetoworkwiththePDBmetadataandnotmovetheapplicationdata.TheunplugoperationcapturesthePDBlineageinanXMLmanifestfile,allowingaPDBtobepluggedintoanothercontainerdatabase.

Thefeaturecomesinhandyindatacenteroperationswhenthedatabasesareexpectedtomovequicklytodifferentservicelevels,withoutimpactingbusinesscontinuity.Anotherveryimportantusecaseoftheplug/unplugfeatureiswhenyouarerequiredtoupgradeorpatchsubsetsofPDBsinacontainer.YoucanunplugaPDBfroma12.1containerandplugitinaOracle12.xcontainerdatabase.

ManageManyasOneThemultitenantarchitectureenablesthe“managemanyasone”capability.OrganizationswhoareadoptingaMultitenantarchitecture,areexpectedtoseeasignificantreductioninoperationalexpensesbymanagingmultipledatabasesasone.Hereisthelistofmultitenantoperationsthatapplytoallthepluggabledatabases:

Backingupthecontainerdatabasebacksuptherootcontainerincludingallthepluggabledatabases.However,pointintimerecoveryatthepluggabledatabaselevelispossible.

NoteYoucanalsobackupjusttheCDB$ROOToraparticularPDB

Inadataguardsetup,allpluggabledatabasesareauto-discoveredatthestandbysite.Therefore,ahighavailabilityofallPDBsismaintainedbyimplementingthedataguardatthecontainerlevel.

NoteInOracleDatabase12.1.0.2,youcanprovisionaPDBonaprimarysitebutdisableitsrecoveryatthestandbysitebyspecifyingSTANDBYS=NONE

Upgradingandpatchingthecontainerdatabaseupgradesorpatchesallthepluggabledatabases.However,ifyouarerequiredtoupgradeorpatchasubsetofpluggabledatabases,youcanunplugandplugintoadifferentcontainerofahigherreleaseorpatchset.

RapidprovisioningPluggabledatabasescanbequicklyprovisionedeitherlocallywithinacontainerorfromaremotecontainer.PDBprovisioningdoesn’tinvolvecopyingthesystemmetadataorthecreationofbackgroundprocesses,therebyspeedingupthecreationprocess.

Apluggabledatabasecanbeprovisionedindifferentwaysaslistedhere:

AfreshPDBfromseed(PDB$SEED)—creatingabrandnewpluggabledatabasefromtheseedPDBisamerecopyofSYSTEMandSYSAUXfilesfromtheseedlocationtothetargetPDBlocationonthedatabaseserver.Clone/copyanexistingPDB—anexistingPDBcanbeclonedlocallywithinthecurrentcontainer.Operationally,cloningaPDBiscopyingthefilestoanewPDBlocation.ThePDBremotecloningfeatureisavailablefromOracleDatabase12c(12.1.0.2).SnapshotCloning—OracleDatabase12csupportssnapshotcloningofpluggabledatabasesoncopy-on-writefilesystems.Byvirtueofthecopy-on-writefeature,snapshotcloningisanextremelyfastmethodofcreatingcopiesofpluggabledatabases.

OracleDatabase12.1.0.2introducednewenhancementstoPDBcloninginamultitenantcontainerdatabase.Theenhancementsarebrieflydescribedhere:

SchemaconsolidationtoPDB-basedconsolidation—youcancreateanewpluggabledatabasebyspecifyingjustthetablespacestobeavailableinthenewPDB.YoucanspecifytablespacesintheUSER_TABLESPACEclauseatthetimeofPDBcreation.Pre12cdatabases,whichearlierusedtheschemaconsolidationapproach,willbenefitfromthisnewfeaturewhilemovingtoOracle12cMultitenant.Metadata-onlyclone—YoucancloneaPDBdatamodel,andnotitsdata,byspecifyingNODATAatthetimeofcloning.Remoteclonenon-CDBasPDB—YoucandirectlycloneanOracle12cnon-CDBasthePDBinamultitenantcontainerdatabase.

CDBResourceManagementResourcemanagementisanessentialexerciseinamultitenantcontainerdatabasethathostsmultipleapplicationdatabases,withacommonSGAandbackgroundprocess.Withmultiplepluggabledatabases,scenariosmayarisewheredatabasesmaycompeteforserverresources.Therequestcongestionmightimpacttheperformanceofcriticaldatabases,thusimpactingbusinessSLAs.TheDatabaseResourceManager(DBRM)featurehasbeenenhancedinOracle12ctoextendsupporttothemultitenantarchitecture.

Inamultitenantenvironment,youcancreateCDBplandirectivestomanagetheallocationoftheCPUasshares,andparallelexecutionslavesacrossthemultiplepluggabledatabases.Intheeventofresourcecongestion,pluggabledatabasesfollowtheCDBresourceplantoprioritizetherequests.

Withinapluggabledatabase,youcancreatetheusualdatabaseresourcemanagementplanstocontroltheconsumptionoftheavailableresourcesacrossconsumergroups.

CommonusersandlocalusersStartingwithOracle12cMultitenantarchitecture,therewillbetwofamiliesofusers,namelycommonusersandlocalusers.ThecontainerDBAcreatesacommonuserintherootcontainer.Localusersaretheonesthatarevisibleandoperationalwithinasinglepluggabledatabase.AlltheusersuntilOracleDatabase11gwillfallunderthecategoryoflocalusers.

Herearetheimportantpointsregardingcommonandlocalusers:

AllcommonusersmuststartwithC##.SYSisanexception.PluggabledatabasesmustgrantCONNECTandCREATESESSIONprivilegetothecommonusertoallowaccesstothecontainer.ThestaticviewsCDB_USERSandDBA_USERShaveanewcolumnCOMMONtodifferentiatecommonandlocalusers.Acommonusercanbeusedtoexecuteagenericscriptacrossmultiplecontainers(usingcatcon.pl).WithOracle12c(12.1.0.2),commonuserscanquerycommonobjectsinrootthe(CDB$ROOT)frommultiplecontainersusingtheCONTAINERSclause.

Oracle12cSQLandPL/SQLnewfeaturesSQListhemostwidelyuseddataaccesslanguagewhilePL/SQLisapopularlanguagethatcanintegrateseamlesslywithSQLcommands.ThebiggestbenefitofrunningPL/SQListhatthecodeprocessinghappensnativelywithintheOracleDatabase.Inthepast,therehavebeendebatesanddiscussionsonserversideprogrammingwhiletheclientinvokesthePL/SQLroutinestoperformatask.Theserversideprogrammingapproachhasmanybenefits.Itreducesthenetworkroundtripsbetweentheclientandthedatabase.ItreducesthecodesizeandeasesthecodeportabilitybecausePL/SQLcanrunonallplatforms,whereverOracleDatabaseissupported.

OracleDatabase12cintroducesmanylanguagefeaturesandenhancementsthatfocusonSQLtoPL/SQLintegration,codemigration,andANSIcompliance.ThissectiondiscussestheSQLandPL/SQLnewfeaturesinOracleDatabase12c.

IDENTITYcolumnsOracleDatabase12cintroducesidentitycolumnsinSQLincompliancewiththeAmericanNationalStandardInstitute(ANSI)SQLstandard.Atablecolumn,markedasIDENTITY,automaticallygeneratesanincrementalnumericvalueatthetimeofrecordcreation.

BeforethereleaseofOracle12c,developershadtocreateanadditionalsequenceintheschemaandassignitsvaluetothecolumnthroughatriggerorinaPL/SQLblock.Thenewfeaturesimplifiescodewritingandbenefitsthemigrationofanon-OracledatabasetoOracle.

ThefollowingscriptdeclaresanidentitycolumninthetableT_ID_COL:

/*Createatablefordemonstrationpurpose*/

CREATETABLEt_id_col

(idNUMBERGENERATEDASIDENTITY,

nameVARCHAR2(20))

/

TheidentitycolumnmetadatacanbequeriedfromthedictionaryviewsUSER_TAB_COLSandUSER_TAB_IDENTITY_COLS.NotethatOracleimplicitlycreatesasequencetogeneratethenumbervaluesforthecolumn.However,Oracleallowstheconfigurationofthesequenceattributesofanidentitycolumn.ThecustomsequenceconfigurationislistedunderIDENTITY_OPTIONSinUSER_TAB_IDENTITY_COLSview:

/*QueryidentitycolumninformationinUSER_TAB_COLS*/

SELECTcolumn_name,data_default,user_generated,identity_column

FROMuser_tab_cols

WHEREtable_name='T_ID_COL'

/

COLUMN_NAMEDATA_DEFAULTUSEIDE

--------------------------------------------------

ID"SCOTT"."ISEQ$$_93001".nextvalYESYES

NAMEYESNO

LetuschecktheattributesoftheprecedingsequencethatOraclehasimplicitlycreated.NotethatthequeryusesREGEXP_SUBSTRtoprintthesequenceconfigurationinmultiplerows:

/*CheckthesequenceconfigurationfromUSER_TAB_IDENTITY_COLSview*/

SELECTtable_name,column_name,generation_type,

REGEXP_SUBSTR(identity_options,'[^,]+',1,LEVEL)identity_options

FROMuser_tab_identity_cols

WHEREtable_name='T_ID_COL'

CONNECTBYREGEXP_SUBSTR(identity_options,'[^,]+',1,level)

ISNOTNULL

/

TABLE_NAMECOLUMN_NAMEGENERATIONIDENTITY_OPTIONS

-----------------------------------------------------------------

T_ID_COLIDALWAYSSTARTWITH:1

T_ID_COLIDALWAYSINCREMENTBY:1

T_ID_COLIDALWAYSMAX_VALUE:9999999999999999999999999999

T_ID_COLIDALWAYSMIN_VALUE:1

T_ID_COLIDALWAYSCYCLE_FLAG:N

T_ID_COLIDALWAYSCACHE_SIZE:20

T_ID_COLIDALWAYSORDER_FLAG:N

7rowsselected

WhileinsertingdatainthetableT_ID_COL,donotincludetheidentitycolumnasitsvalueisautomaticallygenerated:

/*Inserttestdatainthetable*/

BEGIN

INSERTINTOt_id_col(name)VALUES('Allen');

INSERTINTOt_id_col(name)VALUES('Matthew');

INSERTINTOt_id_col(name)VALUES('Peter');

COMMIT;

END;

/

Letuscheckthedatainthetable.Notetheidentitycolumnvalues:

/*Querythetable*/

SELECTid,nameFROMt_id_col

/

IDNAME

-------------------------

1Allen

2Matthew

3Peter

Thesequencecreatedunderthecoversforidentitycolumnsistightlycoupledwiththecolumn.Ifausertriestoinsertauser-definedinputfortheidentitycolumn,theoperationthrowsanexceptionORA-32795:

INSERTINTOt_id_colVALUES(7,'Steyn');

insertintot_id_colvalues(7,'Steyn')

*

ERRORatline1:

ORA-32795:cannotinsertintoageneratedalwaysidentitycolumn

DefaultcolumnvaluetoasequenceinOracle12cOracleDatabase12callowsdeveloperstodefaultacolumndirectlytoasequence‑generatedvalue.TheDEFAULTclauseofatablecolumncanbeassignedtoSEQUENCE.CURRVALorSEQUENCE.NEXTVAL.Thefeaturewillbeusefulwhilemigratingnon-OracledatadefinitionstoOracle.

TheDEFAULTONNULLclauseStartingwithOracleDatabase12c,acolumncanbeassignedadefaultnon-nullvaluewhenevertheusertriestoinsertNULLintothecolumn.ThedefaultvaluewillbespecifiedintheDEFAULTclauseofthecolumnwithanewONNULLextension.

NotethattheDEFAULTONNULLcannotbeusedwithanobjecttypecolumn.

Thefollowingscriptcreatesatablet_def_cols.AcolumnIDhasbeendefaultedtoasequencewhilethecolumnDOJwillalwayshaveanon-nullvalue:

/*Createasequence*/

CREATESEQUENCEseqSTARTWITH100INCREMENTBY10

/

/*Createatablewithacolumndefaultedtothesequencevalue*/

CREATETABLEt_def_cols

(idnumberdefaultseq.nextvalprimarykey,

namevarchar2(30),

dojdatedefaultonnull'01-Jan-2000'

)

/

ThefollowingPL/SQLblockinsertsthetestdata:

/*Insertthetestdatainthetable*/

BEGIN

INSERTINTOt_def_cols(name,doj)values('KATE','27-FEB-2001');

INSERTINTOt_def_cols(name,doj)values('NANCY','17-JUN-1998');

INSERTINTOt_def_cols(name,doj)values('LANCE','03-JAN-2004');

INSERTINTOt_def_cols(name)values('MARY');

COMMIT;

END;

/

QuerythetableandcheckthevaluesfortheIDandDOJcolumns.IDgetsthevaluefromthesequenceSEQwhileDOJforMARYhasbeendefaultedto01-JAN-2000.

/*Querythetabletoverifysequenceanddefaultonnullvalues*/

SELECT*FROMt_def_cols

/

IDNAMEDOJ

---------------------------

100KATE27-FEB-01

110NANCY17-JUN-98

120LANCE03-JAN-04

130MARY01-JAN-00

Supportfor32KVARCHAR2OracleDatabase12csupportstheVARCHAR2,NVARCHAR2,andRAWdatatypesupto32,767bytesinsize.ThepreviousmaximumlimitfortheVARCHAR2(andNVARCHAR2)andRAWdatatypeswas4,000bytesand2,000bytesrespectively.Thesupportforextendedstringdatatypeswillbenefitnon-OracletoOraclemigrations.

ThefeaturecanbecontrolledusingtheinitializationparameterMAX_STRING_SIZE.Itacceptstwovalues:

STANDARD(default)—ThemaximumsizepriortothereleaseofOracleDatabase12cwillapply.EXTENDED—Thenewsizelimitforstringdatatypesapply.NotethataftertheparameterissettoEXTENDED,thesettingcannotberolledback.

Thestepstoincreasethemaximumstringsizeinadatabaseare:

1. RestartthedatabaseinUPGRADEmode.Inthecaseofapluggabledatabase,thePDBmustbeopenedinMIGRATEmode.

2. UsetheALTERSYSTEMcommandtosetMAX_STRING_SIZEtoEXTENDED.3. AsSYSDBA,executethe$ORACLE_HOME/rdbms/admin/utl32k.sqlscript.Thescript

isusedtoincreasethemaximumsizelimitofVARCHAR2,NVARCHAR2,andRAWwhereverrequired.

4. RestartthedatabaseinNORMALmode.5. AsSYSDBA,executeutlrp.sqltorecompiletheschemaobjectswithinvalidstatus.

Thepointstobeconsideredwhileworkingwiththe32ksupportforstringtypesare:

COMPATIBLEmustbe12.0.0.0AftertheparameterissettoEXTENDED,theparametercannotberolledbacktoSTANDARD

InRACenvironments,alltheinstancesofthedatabasecomplywiththesettingofMAX_STRING_SIZE

RowlimitingusingFETCHFIRSTForTop-Nqueries,OracleDatabase12cintroducesanewclause,FETCHFIRST,tosimplifythecodeandcomplywithANSISQLstandardguidelines.Theclauseisusedtolimitthenumberofrowsreturnedbyaquery.ThenewclausecanbeusedinconjunctionwithORDERBYtoretrieveTop-Nresults.

TherowlimitingclausecanbeusedwiththeFORUPDATEclauseinanSQLquery.Inthecaseofamaterializedview,thedefiningqueryshouldnotcontaintheFETCHclause.

Anothernewclause,OFFSET,canbeusedtoskiptherecordsfromthetopormiddle,beforelimitingthenumberofrows.Forconsistentresults,theoffsetvaluemustbeapositivenumber,lessthanthetotalnumberofrowsreturnedbythequery.Forallotheroffsetvalues,thevalueiscountedaszero.

KeywordswiththeFETCHFIRSTclauseare:

FIRST|NEXT—SpecifyFIRSTtobeginrowlimitingfromthetop.UseNEXTwithOFFSETtoskipcertainrows.ROWS|PERCENT—Specifythesizeoftheresultsetasafixednumberofrowsorpercentageoftotalnumberofrowsreturnedbythequery.ONLY|WITHTIES—UseONLYtofixthesizeoftheresultset,irrespectiveofduplicatesortkeys.Ifyouwantallrecordswithmatchingsortkeys,specifyWITHTIES.

ThefollowingquerydemonstratestheuseoftheFETCHFIRSTandOFFSETclausesinTop-Nqueries:

/*Createthetesttable*/

CREATETABLEt_fetch_first

(empnoVARCHAR2(30),

deptnoNUMBER,

salNUMBER,

hiredateDATE)

/

ThefollowingPL/SQLblockinsertssampledatafortesting:

/*InsertthetestdatainT_FETCH_FIRSTtable*/

BEGIN

INSERTINTOt_fetch_firstVALUES(101,10,1500,'01-FEB-2011');

INSERTINTOt_fetch_firstVALUES(102,20,1100,'15-JUN-2001');

INSERTINTOt_fetch_firstVALUES(103,20,1300,'20-JUN-2000');

INSERTINTOt_fetch_firstVALUES(104,30,1550,'30-DEC-2001');

INSERTINTOt_fetch_firstVALUES(105,10,1200,'11-JUL-2012');

INSERTINTOt_fetch_firstVALUES(106,30,1400,'16-AUG-2004');

INSERTINTOt_fetch_firstVALUES(107,20,1350,'05-JAN-2007');

INSERTINTOt_fetch_firstVALUES(108,20,1000,'18-JAN-2009');

COMMIT;

END;

/

TheSELECTquerypullsinthetop-5rowswhensortedbytheirsalary:

/*Querytolisttop-5employeesbysalary*/

SELECT*

FROMt_fetch_first

ORDERBYsalDESC

FETCHFIRST5ROWSONLY

/

EMPNODEPTNOSALHIREDATE

------------------------------

104 30155030-DEC-01

101 10150001-FEB-11

106 30140016-AUG-04

107 20135005-JAN-07

103 20130020-JUN-00

TheSELECTqueryliststhetop25%ofemployees(2)whensortedbytheirhiredate:

/*Querytolisttop-25%employeesbyhiredate*/

SELECT*

FROMt_fetch_first

ORDERBYhiredateFETCHFIRST25PERCENTROWONLY

/

EMPNODEPTNOSALHIREDATE

----------------------------

10320130020-JUN-00

10220110015-JUN-01

TheSELECTqueryskipsthefirstfiveemployeesanddisplaysthenexttwo—the6thand7themployeedata:

/*Querytolist2employeesafterskippingfirst5employees*/

SELECT*

FROMt_fetch_first

ORDERBYSALDESC

OFFSET5ROWSFETCHNEXT2ROWSONLY

/

InvisiblecolumnsOracleDatabase12csupportsinvisiblecolumns,whichimpliesthatausercancontrolthevisibilityofacolumn.Acolumnmarkedinvisibledoesnotappearinthefollowingoperations:

SELECT*FROMqueriesonthetableSQL*PlusDESCRIBEcommandLocalrecordsof%ROWTYPEOracleCallInterface(OCI)description

AcolumncanbemadeinvisiblebyspecifyingtheINVISIBLEclauseagainstthecolumn.Columnsofalltypes(exceptuser-definedtypes),includingvirtualcolumns,canbemarkedinvisible,providedthetablesarenottemporarytables,externaltables,orclustered.TheSELECTstatementcanexplicitlyselectaninvisiblecolumn.Similarly,theINSERTstatementwillnotinsertvaluesinaninvisiblecolumnunlessexplicitlyspecified.

Furthermore,atablecanbepartitionedbasedonaninvisiblecolumn.Acolumnretainsitsnullityfeatureevenafteritismadeinvisible.Aninvisiblecolumncanbemadevisible,buttheorderingofthecolumninthetablemaychange.

Inthefollowingscript,thecolumnNICKNAMEissetasinvisibleinthetablet_inv_col:

/*Createatabletodemonstrateinvisiblecolumns*/

CREATETABLEt_inv_col

(idNUMBER,

nameVARCHAR2(30),

nicknameVARCHAR2(10)INVISIBLE,

dobDATE

)

/

Theinformationabouttheinvisiblecolumnscanbefoundinuser_tab_cols.Notethattheinvisiblecolumnismarkedashidden:

/*QuerytheUSER_TAB_COLSformetadatainformation*/

SELECTcolumn_id,

column_name,

hidden_column

FROMuser_tab_cols

WHEREtable_name='T_INV_COL'

ORDERBYcolumn_id

/

COLUMN_IDCOLUMN_NAMEHID

-------------------------

1IDNO

2NAMENO

3DOBNO

NICKNAMEYES

Hiddencolumnsaredifferentfrominvisiblecolumns.Invisiblecolumnscanbemadevisibleandviceversa,buthiddencolumnscannotbemadevisible.

IfwetrytomaketheNICKNAMEvisibleandNAMEinvisible,observethechangeincolumnordering:

/*ScripttochangevisibilityofNICKNAMEcolumn*/

ALTERTABLEt_inv_colMODIFYnicknameVISIBLE

/

/*ScripttochangevisibilityofNAMEcolumn*/

ALTERTABLEt_inv_colMODIFYnameINVISIBLE

/

/*QuerytheUSER_TAB_COLSformetadatainformation*/

SELECTcolumn_id,

column_name,

hidden_column

FROMuser_tab_cols

WHEREtable_name='T_INV_COL'

ORDERBYcolumn_id

/

COLUMN_IDCOLUMN_NAMEHID

-------------------------

1IDNO

2DOBNO

3NICKNAMENO

NAMEYES

TemporaldatabasesTemporaldatabaseswerereleasedasanewfeatureinANSISQL:2011.Thetermtemporaldatacanbeunderstoodasapieceofinformationthatcanbeassociatedwithaperiodwithinwhichtheinformationisvalid.BeforethefeaturewasincludedinOracleDatabase12c,datawhosevalidityislinkedwithatimeperiodhadtobehandledeitherbytheapplicationorusingmultiplepredicatesinthequeries.Oracle12cpartiallyinheritsthefeaturefromtheANSISQL:2011standardtosupporttheentitieswhosebusinessvaliditycanbebracketedwithatimedimension.

ThetemporaldatabasefeatureinOracleDatabase12cisdifferentfromthetotalrecallfeatureinOracleDatabase11g.Thetotalrecallfeaturerecordsthetransactiontimeofthedatainthedatabasetosecurethetransactionvalidityandnotthefunctionalvalidity.Forexample,aninvestmentschemeisactivebetweenJanuarytoDecember.Thedaterecordedinthedatabaseatthetimeofdataloadingisthetransactiontimestamp.

TipStartingfromOracle12c,theTotalRecallfeaturehasbeenrebrandedasFlashbackDataArchiveandhasbeenmadeavailableforallversionsofOracleDatabase.

ThevalidtimetemporalfeaturecanbeenabledforatablebyaddingatimedimensionusingthePERIODFORclauseonthedateortimestampcolumnsofthetable.Thefollowingscriptcreatesatablet_tmp_dbwithvalidtimetemporal:

/*Createtablewithvalidtimetemporal*/

CREATETABLEt_tmp_db(

idNUMBER,

nameVARCHAR2(30),

policy_noVARCHAR2(50),

policy_termnumber,

pol_st_datedate,

pol_end_datedate,

PERIODFORpol_valid_time(pol_st_date,pol_end_date))

/

Createsomesampledatainthetable:

/*Inserttestdatainthetable*/

BEGIN

INSERTINTOt_tmp_db

VALUES(100,'Packt','PACKT_POL1',1,'01-JAN-2015','31-DEC-2015');

INSERTINTOt_tmp_db

VALUES(110,'Packt','PACKT_POL2',2,'01-JAN-2015','30-JUN-2015');

INSERTINTOt_tmp_db

VALUES(120,'Packt','PACKT_POL3',3,'01-JUL-2015','31-DEC-2015');

COMMIT;

END;

/

LetussetthecurrenttimeperiodwindowusingDBMS_FLASHBACK_ARCHIVE.GranttheEXECUTEprivilegeonthepackagetothescottuser.

/*Connecttosysdbatograntexecuteprivilegetoscott*/

connsys/oracleassysdba

GRANTEXECUTEONdbms_flashback_archivetoscott

/

Grantsucceeded.

/*Connecttoscott*/

connscott/tiger

/*SetthevalidtimeperiodasCURRENT*/

EXECDBMS_FLASHBACK_ARCHIVE.ENABLE_AT_VALID_TIME('CURRENT');


SettingthevalidtimeperiodasCURRENTmeansthatallthetableswithavalidtimetemporalwillonlylisttherowsthatarevalidwithrespecttotoday’sdate.Youcansetthevalidtimetoaparticulardatetoo.

/*Querythetable*/

SELECT*fromt_tmp_db

/

IDPOLICY_NOPOL_ST_DATEPOL_END_DATE

---------------------------------------------------------------

100PACKT_POL101-JAN-1531-DEC-15

110PACKT_POL201-JAN-1530-JUN-15

TipDuetoadependencyonthecurrentdate,theresultmayvarywhenthereaderrunstheprecedingqueries.

ThequerylistsonlythosepoliciesthatareactiveasofMarch2015.Since,thethirdpolicystartsinJuly2015,itiscurrentlynotactive.

In-DatabaseArchivingOracleDatabase12cintroducesIn-DatabaseArchivingtoarchivethelowprioritydatainatable.Theinactivedataremainsinthedatabasebutisnotvisibletotheapplication.

Youcanmarkolddataforarchival,whichisnotactivelyrequiredintheapplicationexceptforregulatorypurposes.Althoughthearchiveddataisnotvisibletotheapplication,itisavailableforqueryingandmanipulation.Inaddition,thearchiveddatacanbecompressedtoimprovebackupperformance.

AtablecanbeenabledbyspecifyingtheROWARCHIVALclauseatthetablelevel,whichaddsahiddencolumnORA_ARCHIVE_STATEtothetablestructure.Thecolumnvaluemustbeupdatedtomarkarowforarchival.Forexample:

/*Createatablewithrowarchiving*/

CREATETABLEt_row_arch(

xnumber,

ynumber,

znumber)ROWARCHIVAL

/

WhenwequerythetablestructureintheUSER_TAB_COLSview,wefindanadditionalhiddencolumn,whichOracleimplicitlyaddstothetable:

/*Querythecolumnsinformationfromuser_tab_colsview*/

SELECTcolumn_id,column_name,data_type,hidden_column

FROMuser_tab_cols

WHEREtable_name='T_ROW_ARCH'

/

COLUMN_IDCOLUMN_NAME DATA_TYPEHID

-----------------------------------------

ORA_ARCHIVE_STATEVARCHAR2YES

1XNUMBERNO

2YNUMBERNO

3ZNUMBERNO

Letuscreatetestdatainthetable:

/Inserttestdatainthetable*/

BEGIN

INSERTINTOt_row_archVALUES(10,20,30);




commit;

END;

/

Fortestingpurpose,letusarchivetherowsinthetablewhereX>50byupdatingtheora_archive_statecolumn:

/*UpdateORA_ARCHIVE_STATEcolumninthetable*/

UPDATEt_row_arch

SETora_archive_state=1

WHEREx>50

/

COMMIT

/

Bydefault,thesessiondisplaysonlytheactiverecordsfromanarchival-enabledtable:

/*Querythetable*/

SELECT*

FROMt_row_arch

/

XYZ

------------------------

102030

112233

213243

Ifyouwishtodisplayalltherecords,changethesessionsetting:

/*Changethesessionparametertodisplaythearchivedrecords*/

ALTERSESSIONSETROWARCHIVALVISIBILITY=ALL

/

Sessionaltered.

/*Querythetable*/

SELECT*

FROMt_row_arch

/

XYZ

------------------------------

102030

112233

213243

518213

DefiningaPL/SQLsubprogramintheSELECTqueryandPRAGMAUDFOracleDatabase12cincludestwonewfeaturestoenhancetheperformanceoffunctionswhencalledfromSELECTstatements.WithOracle12c,aPL/SQLsubprogramcanbecreatedinlinewiththeSELECTqueryintheWITHclausedeclaration.ThefunctioncreatedintheWITHclausesubqueryisnotstoredinthedatabaseschemaandisavailableforuseonlyinthecurrentquery.SinceaprocedurecreatedintheWITHclausecannotbecalledfromtheSELECTquery,itcanbecalledinthefunctioncreatedinthedeclarationsection.Thefeaturecanbeveryhandyinread-onlydatabaseswherethedeveloperswerenotabletocreatePL/SQLwrappers.

OracleDatabase12caddsthenewPRAGMAUDFtocreateastandalonefunctionwiththesameobjective.

Earlier,theSELECTqueriescouldinvokeaPL/SQLfunction,providedthefunctiondidn’tchangethedatabasepuritystate.ThequeryperformancewoulddegradebecauseofthecontextswitchfromSQLtothePL/SQLengine(andviceversa)andthedifferentmemoryrepresentationsofdatatypeintheprocessingengines.

Inthefollowingexample,thefunctionfun_with_plsqlcalculatestheannualcompensationofanemployee

/*CreateafunctioninWITHclausedeclaration*/

WITHFUNCTIONfun_with_plsql(p_salNUMBER)RETURNNUMBERIS

BEGIN

RETURN(p_sal*12);

END;

SELECTename,deptno,fun_with_plsql(sal)"annual_sal"

FROMemp

/

ENAMEDEPTNOannual_sal

-----------------------------

SMITH209600

ALLEN3019200

WARD3015000

JONES2035700

MARTIN3015000

BLAKE3034200

CLARK1029400

SCOTT2036000

KING1060000

TURNER3018000

ADAMS2013200

JAMES3011400

FORD2036000

MILLER1015600

14rowsselected.

Note

IfthequerycontainingtheWITHclausedeclarationisnotatop-levelstatement,thenthetoplevelstatementmustusetheWITH_PLSQLhint.ThehintisusedifINSERT,UPDATE,orDELETEstatementsaretryingtouseaSELECTwithaWITHclausedefinition.FailuretoincludethehintresultsinanexceptionORA-32034:unsupporteduseofWITHclause.

AfunctioncanbecreatedwiththePRAGMAUDFtoinformthecompilerthatthefunctionisalwayscalledinaSELECTstatement.Notethatthestandalonefunctioncreatedinthefollowingcodecarriesthesamenameastheoneinthelastexample.ThelocalWITHclausedeclarationtakesprecedenceoverthestandalonefunctionintheschema.

/*CreateafunctionwithPRAGMAUDF*/

CREATEORREPLACEFUNCTIONfun_with_plsql(p_salNUMBER)

RETURNNUMBERis

PRAGMAUDF;

BEGIN

RETURN(p_sal*12);

END;

/

Sincetheobjectiveofthefeatureisperformance,letusgoaheadwithacasestudytocomparetheperformancewhenusingastandalonefunction,aPRAGMAUDFfunction,andaWITHclausedeclaredfunction.

TestsetupTheexerciseusesatesttablewith1millionrows,loadedwithrandomdata.

/*Createatableforperformanceteststudy*/

CREATETABLEt_fun_plsql

(idnumber,

strvarchar2(30))

/

/*Generateandloadrandomdatainthetable*/

INSERT/*+APPEND*/INTOt_fun_plsql

SELECTROWNUM,DBMS_RANDOM.STRING('X',20)

FROMdual

CONNECTBYLEVEL<=1000000

/

COMMIT

/

Case1:CreateaPL/SQLstandalonefunctionasitusedtobeuntilOracleDatabase12c.Thefunctioncountsthenumbersinthestrcolumnofthetable.

/*CreateastandalonefunctionwithoutOracle12cenhancements*/

CREATEORREPLACEFUNCTIONf_count_num(p_strVARCHAR2)

RETURNPLS_INTEGERIS

BEGIN

RETURN(REGEXP_COUNT(p_str,'\d'));

END;

/

ThePL/SQLblockmeasurestheelapsedandCPUtimewhenworkingwithapre-Oracle12cstandalonefunction.Thesenumberswillserveasthebaselineforourcase

study.

/*Setserveroutputontodisplaymessages*/

SETSERVEROUTPUTON

/*Anonymousblocktomeasureperformanceofastandalonefunction*/

DECLARE

l_el_timePLS_INTEGER;

l_cpu_timePLS_INTEGER;

CURSORC1IS

SELECTf_count_num(str)FROMt_fun_plsql;

TYPEt_tab_recISTABLEOFPLS_INTEGER;

l_tabt_tab_rec;

BEGIN

l_el_time:=DBMS_UTILITY.GET_TIME();

l_cpu_time:=DBMS_UTILITY.GET_CPU_TIME();

OPENc1;

FETCHc1BULKCOLLECTINTOl_tab;

CLOSEc1;

DBMS_OUTPUT.PUT_LINE('Case1:Performanceofastandalonefunction');

DBMS_OUTPUT.PUT_LINE('Totalelapsed

time:'||to_char(DBMS_UTILITY.GET_TIME()-l_el_time));

DBMS_OUTPUT.PUT_LINE('TotalCPU

time:'||to_char(DBMS_UTILITY.GET_CPU_TIME()-l_cpu_time));

END;

/

Performanceofastandalonefunction:

Totalelapsedtime:1559

TotalCPUtime:1366


Case2:CreateaPL/SQLfunctionusingPRAGMAUDFtocountthenumbersinthestrcolumn.

/*CreatethefunctionwithPRAGMAUDF*/

CREATEORREPLACEFUNCTIONf_count_num_pragma(p_strVARCHAR2)

RETURNPLS_INTEGERIS

PRAGMAUDF;

BEGIN

RETURN(REGEXP_COUNT(p_str,'\d'));

END;

/

LetusnowchecktheperformanceofthePRAGMAUDFfunctionusingthefollowingPL/SQLblock.


SETSERVEROUTPUTON

/*AnonymousblocktomeasureperformanceofaPRAGMAUDFfunction*/

DECLARE



CURSORC1IS

SELECTf_count_num_pragma(str)FROMt_fun_plsql;


l_tabt_tab_rec;

BEGIN

l_el_time:=DBMS_UTILITY.GET_TIME();

l_cpu_time:=DBMS_UTILITY.GET_CPU_TIME();

OPENc1;

FETCHc1BULKCOLLECTINTOl_tab;

CLOSEc1;

DBMS_OUTPUT.PUT_LINE('Case2:PerformanceofaPRAGMAUDFfunction');





END;

/

PerformanceofaPRAGMAUDFfunction:


TotalCPUtime:582


Case3:ThefollowingPL/SQLblockdynamicallyexecutesthefunctionintheWITHclausesubquery.Notethat,unlikeotherSELECTstatements,aSELECTquerywithaWITHclausedeclarationcannotbeexecutedstaticallyinthebodyofaPL/SQLblock.


SETSERVEROUTPUTON

/*Anonymousblocktomeasureperformanceofinlinefunction*/

DECLARE



l_sqlVARCHAR2(32767);

c1sys_refcursor;


l_tabt_tab_rec;

BEGIN

l_el_time:=DBMS_UTILITY.get_time;

l_cpu_time:=DBMS_UTILITY.get_cpu_time;

l_sql:='WITHFUNCTIONf_count_num_with(p_strVARCHAR2)

RETURNNUMBERIS

BEGIN

RETURN(REGEXP_COUNT(p_str,'''||'\'||'d'||'''));

END;

SELECTf_count_num_with(str)FROMt_fun_plsql';

OPENc1FORl_sql;

FETCHc1bulkcollectINTOl_tab;

CLOSEc1;

DBMS_OUTPUT.PUT_LINE('Case3:Performanceofaninlinefunction');





END;

/

Performanceofaninlinefunction:


TotalCPUtime:718


ComparativeanalysisComparingtheresultsfromtheprecedingthreecases,it’sclearthattheOracle12cflavorofPL/SQLfunctionsout-performsthepre-12cstandalonefunctionbyahighmargin.Fromthefollowingmatrix,itisapparentthattheusageofthePRAGMAUDForWITHclausedeclarationenhancesthecodeperformanceby(roughly)afactorof2.

CaseDescription ElapsedTime

CPUtime

PerformancegainfactorbyCPUtime

StandalonePL/SQLfunctioninpre-Oracle12cdatabase 1559 1336 1x

StandalonePL/SQLPRAGMAUDFfunctioninOracle12c 664 582 2.3x

FunctioncreatedinWITHclausedeclarationinOracle12c 830 718 1.9x

NoteNotethatthenumbersmayslightlydifferinthereader’stestingenvironmentbutyoushouldbeabletodrawthesameconclusionbycomparingthem.

ThePL/SQLprogramunitwhitelistingPriortoOracle12c,astandaloneorpackagedPL/SQLunitcouldbeinvokedbyallotherprogramsinthesession’sschema.OracleDatabase12callowsuserstopreventunauthorizedaccesstoPL/SQLprogramunits.Youcannowspecifythelistofwhitelistprogramunitsthatcaninvokeaparticularprogram.ThePL/SQLprogramheaderorthepackagespecificationcanspecifythelistofprogramunitsintheACCESSIBLEBYclauseintheprogramheader.Allotherprogramunits,includingcross-schemareferences(evenSYSownedobjects),tryingtoaccessaprotectedsubprogramwillreceiveanexception,PLS-00904:insufficientprivilegestoaccessobject[objectname].

Thefeaturecanbeveryusefulinanextremelysensitivedevelopmentenvironment.Suppose,apackagePKG_FIN_PROCcontainsthesensitiveimplementationroutinesforfinancialinstitutions,thepackagedsubprogramsarecalledbyanotherPL/SQLpackagePKG_FIN_INTERNALS.TheAPIlayerexposesafixedlistofprogramsthroughapublicAPIcalledPKG_CLIENT_ACCESS.InordertorestrictaccesstothepackagedroutinesinPKG_FIN_PROC,theuserscanbuildasafetynetsoastoallowaccesstoonlyauthorizedprograms.

ThefollowingPL/SQLpackagePKG_FIN_PROCcontainstwosubprograms—P_FIN_QTR

andP_FIN_ANN.TheACCESSIBLEBYclauseincludesPKG_FIN_INTERNALSwhichmeansthatallotherprogramunits,includinganonymousPL/SQLblocks,areblockedfrominvokingPKG_FIN_PROCconstructs.

/*Packagewiththeaccessiblebyclause*/

CREATEORREPLACEPACKAGEpkg_fin_proc

ACCESSIBLEBY(PACKAGEpkg_fin_internals)

IS

PROCEDUREp_fin_qtr;

PROCEDUREp_fin_ann;

END;

/

TipTheACCESSIBLEBYclausecanbespecifiedforschema-levelprogramsonly.

Let’sseewhathappenswhenweinvokethepackagedsubprogramfromananonymousPL/SQLblock.

/*InvokethepackagedsubprogramfromthePL/SQLblock*/

BEGIN

pkg_fin_proc.p_fin_qtr;

END;

/

pkg_fin_proc.p_fin_qtr;

*

ERRORatline2:

ORA-06550:line2,column4:

PLS-00904:insufficientprivilegetoaccessobjectPKG_FIN_PROC


PL/SQL:Statementignored

Well,thecompilerthrowsanexceptionasinvokingthewhitelistedpackagefromananonymousblockisnotallowed.

TheACCESSIBLEBYclausecanbeincludedintheheaderinformationofPL/SQLproceduresandfunctions,packages,andobjecttypes.

GrantingrolestoPL/SQLprogramunitsBeforeOracleDatabase12c,aPL/SQLunitcreatedwiththedefiner’srights(defaultAUTHID)alwaysexecutedwiththedefiner’srights,whetherornottheinvokerhastherequiredprivileges.Itmayleadtoanunfairsituationwheretheinvokingusermayperformunwantedoperationswithoutneedingthecorrectsetofprivileges.Similarlyforaninvoker’srightunit,iftheinvokinguserpossessesahighersetofprivilegesthanthedefiner,hemightendupperformingunauthorizedoperations.

OracleDatabase12csecuresthedefiner’srightsbyallowingthedefiningusertograntcomplementaryrolestoindividualPL/SQLsubprogramsandpackages.Fromthesecuritystandpoint,thegrantingofrolestoschemalevelsubprograms,providesgranularcontrolastheprivilegesoftheinvokerarevalidatedatthetimeofexecution.

Inthefollowingexample,wewillcreatetwousers:U1andU2.TheuserU1createsaPL/SQLprocedureP_INC_PRICEthataddsasurchargetothepriceofaproductbyacertainamount.U1grantstheexecuteprivilegetouserU2.

TestsetupLet’screatetwousersandgivethemtherequiredprivileges.

/*Createauserwithapassword*/

CREATEUSERu1IDENTIFIEDBYu1

/

Usercreated.

/*Grantconnectprivilegestotheuser*/

GRANTCONNECT,RESOURCETOu1

/

Grantsucceeded.

/*Createauserwithapassword*/

CREATEUSERu2IDENTIFIEDBYu2

/

Usercreated.

/*Grantconnectprivilegestotheuser*/

GRANTCONNECT,RESOURCETOu2

/

Grantsucceeded.

TheuserU1containsthePRODUCTStable.Let’screateandpopulatethetable.

/*ConnecttoU1*/

CONNu1/u1

/*CreatethetablePRODUCTS*/

CREATETABLEproducts

(

prod_idINTEGER,

prod_nameVARCHAR2(30),

prod_catVARCHAR2(30),

priceINTEGER

)

/

/*Insertthetestdatainthetable*/

BEGIN

DELETEFROMproducts;

INSERTINTOproductsVALUES(101,'Milk','Dairy',20);

INSERTINTOproductsVALUES(102,'Cheese','Dairy',50);

INSERTINTOproductsVALUES(103,'Butter','Dairy',75);

INSERTINTOproductsVALUES(104,'Cream','Dairy',80);

INSERTINTOproductsVALUES(105,'Curd','Dairy',25);

COMMIT;

END;

/

Theprocedurep_inc_priceisdesignedtoincreasethepriceofaproductbyagivenamount.Notethattheprocedureiscreatedwiththedefiner’srights.

/*Createtheprocedurewiththedefiner'srights*/

CREATEORREPLACEPROCEDUREp_inc_price

(p_prod_idNUMBER,p_amtNUMBER)

IS

BEGIN

UPDATEproducts

SETprice=price+p_amt

WHEREprod_id=p_prod_id;

END;

/

TheuserU1grantsexecuteprivilegeonp_inc_pricetoU2.

/*GrantexecuteontheproceduretotheuserU2*/

GRANTEXECUTEONp_inc_priceTOU2

/

TheuserU2logsinandexecutestheprocedureP_INC_PRICEtoincreasethepriceofMilkby5units.

/*ConnecttoU2*/

CONNu2/u2

/*InvoketheprocedureP_INC_PRICEinaPL/SQLblock*/

BEGIN

U1.P_INC_PRICE(101,5);

COMMIT;

END;

/


Thelastcodelistingexposesagrayarea.TheuserU2,thoughnotauthorizedtoviewPRODUCTSdata,manipulatesitsdatawiththedefiner’srights.

Weneedasolutiontotheproblem.Thefirststepistochangetheprocedurefromdefiner’s

rightstoinvoker’srights.

/*ConnecttoU1*/

CONNu1/u1

/*Modifytheprivilegeauthenticationfortheproceduretoinvoker's

rights*/

CREATEORREPLACEPROCEDUREp_inc_price

(p_prod_idNUMBER,p_amtNUMBER)

AUTHIDCURRENT_USER

IS

BEGIN

UPDATEproducts

SETprice=price+p_amt

WHEREprod_id=p_prod_id;

END;

/

Now,ifweexecutetheprocedurefromU2,itthrowsanexceptionbecauseitcouldn’tfindthePRODUCTStableinitsschema.

/*ConnecttoU2*/

CONNu2/u2


BEGIN


COMMIT;

END;

/

BEGIN

*

ERRORatline1:

ORA-00942:tableorviewdoesnotexist

ORA-06512:at"U1.P_INC_PRICE",line5

ORA-06512:atline2

Inasimilarscenariointhepast,thedatabaseadministratorscouldhaveeasilygrantedselectorupdatedprivilegestoU2,whichisnotanoptimalsolutionfromasecuritystandpoint.Oracle12callowsuserstocreateprogramunitswithinvoker’srightsbutgranttherequiredrolestotheprogramunitsandnottheusers.So,aninvokerrightunitexecuteswithinvoker’sprivileges,plusthePL/SQLprogramrole.

Let’scheckoutthestepstocreatearoleandassignittotheprocedure.SYSDBAcreatestheroleandassignsittotheuserU1.UsingtheADMINorDELEGATEoptionwiththegrantenablestheusertogranttheroletootherentities.

/*ConnecttoSYSDBA*/

CONNsys/oracleassysdba

/*Createarole*/

CREATEROLEprod_role

/

/*GrantroletouserU1withdelegateoption*/

GRANTprod_roleTOU1WITHDELEGATEOPTION

/

Now,userU1assignstherequiredsetofprivilegestotherole.Theroleisthenassignedto

therequiredsubprogram.Notethatonlyroles,andnotindividualprivileges,canbeassignedtotheschemalevelsubprograms.

/*ConnecttoU1*/

CONNu1/u1

/*GrantSELECTandUPDATEprivilegesonPRODUCTStotherole*/

GRANTSELECT,UPDATEONPRODUCTSTOprod_role

/

/*Grantroletotheprocedure*/

GRANTprod_roleTOPROCEDUREp_inc_price

/

UserU2triestoexecutetheprocedureagain.Theprocedureissuccessfullyexecutedwhichmeansthevalueof“Milk”hasbeenincreasedby5units.

/*ConnecttoU2*/

CONNu2/u2


BEGIN


COMMIT;

END;

/


UserU1verifiestheresultwithaSELECTquery.

/*ConnecttoU1*/

CONNu1/u1

/*Querythetabletoverifythechange*/

SELECT*

FROMproducts

/

PROD_IDPROD_NAMEPROD_CATPRICE

----------------------------------------

101MilkDairy25

102CheeseDairy50

103ButterDairy75

104CreamDairy80

105CurdDairy25

MiscellaneousPL/SQLenhancementsBesidestheprecedingkeyfeatures,therearealotofnewfeaturesinOracle12c.Thelistoffeaturesisasfollows:

Aninvokerrightsfunctioncanberesult-cached—PriortoOracleDatabase12conlythedefiners’programswereallowedtocachetheirresults.Oracle12caddstheinvokinguser’sidentitytotheresultcachetomakeitindependentofthedefiner.ThecompilationparameterPLSQL_DEBUGhasbeendeprecated.Twoconditionalcompilationinquirydirectives$$PLSQL_UNIT_OWNERand$$PLSQL_UNIT_TYPEhavebeenimplemented.

TheOracleDatabase12c(12.1.0.2)In-MemoryoptionTheOracleDatabase12.1.0.2introducestheIn-Memoryoptionthathasthecapabilitytospeedupreal-timeanalyticsbyanorderofmagnitude.Thefasteranalyticscomplementsandenablesreal-timedecisionmaking.Long-runningreportsandad-hocanalyticalqueriesareexpectedtobenefitthemost.Thefeaturecanbeimplementedwithoutanyapplicationchangesandworkstransparentlywithnomanualhindrance,thusresultinginimprovedproductivity.

ThechallengeEnterpriseapplicationshavebeenreportedtohavemixedworkloads—thatis,OLTPworkloadsandanalyticsprocessing.Inthepast,therehavebeenacoupleofapproachestosegregatingtheworkloads.Mixedworkloadproductiondatabasescanrunonthesamesystem,butrunningbothofthemsimultaneouslywoulddegradetheOLTPperformance.Runningworkloadsonseparateserversystemsimpactsthereal-timedecisionmakingbecausedataontheanalyticsserverhastoberefreshedfromtimetotime.

TheproblemstatementandOracleDatabase12cIn-MemoryOracleDatabaseisatrustedrelationaldatabasemanagementsystemthatstoresdatainarowformat.Fortransactionaldatabases,datastoredinarowformatisamandatebecausetransactionsworkonarecordbasisandrequirealltheattributesofatableinasinglefetch.Ontheotherhand,dataanalyticsandreports,whichrunonfewcolumnsofdatawhilealsospanningmanyrows,workwellwiththecolumnarformat.Untilnow,enterpriseswereforcedtochooseeitherofthetwoformats.

OracleDatabase12cIn-Memoryallowsthedatabasetoberepresentedinarowformataswellasacolumnarformat,thusprovidingtheflavorofa“dual-format”architecturewithinthedatabase.Apieceofdatacanberepresentedinarowformataswellascolumnarformat.Thetransactionscontinuetofollowtherowformatofthedatawhiletheanalyticsworkloadworkwiththecolumnarformat.Theanalyticsgetmorereal-timeasthecolumnarformatacceleratesitbyanorderofmagnitude.Thebest-of-both-worldsstrategyisenabledbyswitchingontheIn-MemoryfeatureintheOracleDatabase.

TheIn-Memoryfeaturemarksamemoryarea(knownastheIn-MemoryColumnStore)withintheSystemGlobalArea(SGA).Thismemoryspaceisusedtoholdtheobjectsfrequentlyreferencedbytheanalyticsqueriesandreports.ItimpliesthatenablingtheIn-Memoryfeatureforadatabasedoesn’trequiredoublememoryrequirements.However,databasesmayrequiresomeadditionalmemorytoaccommodatetheiractiveobjectsintheIn-Memorystore.

OracleDatabase12cIn-MemoryoptionfeaturesTheOracleDatabase12cIn-Memoryfeaturewasreleasedasanoptioninthepatchsetrelease(12.1.0.2)ofOracleDatabase12cRelease1.Thefollowinglistoffeaturesincludessomemust-knowinformationaboutthisoption:

TheIn-Memorycolumnstoreisnotareplacementforthebuffercache;rather,itsupplementsit.In-MemoryColumnStoreisanewstaticpoolwithintheSystemGlobalArea(SGA).BeingIn-Memory,itisnon-persistentandnon-logging.ItisnotaffectedbyAutomaticMemoryManagementandtheresidentobjectsstaypopulateduntiltheyaremanuallyflushedout.AdministratorsorusersareauthorizedtoidentifythoseobjectswhichwhenpopulatedintheIn-Memorycolumnstore,wouldyieldthebestperformance.AllobjectsexceptIndexOrganizedTables,Clusteredtables,LONGcolumns,andOut-of-LineLOBscanbepopulatedintheIn-Memorycolumnstore.TheOracleDatabaseoptimizerisfullyawareoftheIn-memorystore;itdecideswhichquerywouldbenefitfromthebuffercacheorin-memorycolumnarstore.Itisalicensedoption,availablestartingfromOracleDatabase12.1.0.2Enterpriseedition.

TheOracleDatabase12cIn-MemoryArchitectureTheSystemGlobalAreacontainsanewstaticpool,knownastheIn-Memorycolumnstore.ThesegmentsthataremarkedandpopulatedintheIn-Memorycolumnstoreareorientedinthecolumnarformat.DivingdeepintothetechnicalaspectsofIn-Memorycolumnstore,thestaticpoolcomprisesoftwopools:theIMCU(or1MB)poolandtheSMU(or64KB)pool.TheIMCUpoolcomprisesIn-memorycompressionunits(IMCU)thatholdtheactualdatainacolumnarformat.ForeachIMCU,thereisaco-relatedSMUtostoretheIMCU’smetadataandatransactionjournal.Thedistributionof1MBand64KBpoolsarebasedcompletelyoninternalfactors.ThecurrentallocationcanbeviewedundertheV$INMEMORY_AREAdictionaryview.ThefollowingfigureshowsthearchitectureofSGAandtheIn-MemorycolumnstoreinOracleDatabase12c:

ControllingtheIn-MemorycolumnstoreTheIn-MemoryColumnStorecanbeconfiguredthroughanewsetofinitializationparameters,introducedinOracle12c.TheseparameterscontrolIn-Memorydynamicssuchassizing,theoptimizer’sbehavior,andworkerprocessestobedeployedforthepopulation.Hereisthelistofinitializationparameters:

INMEMORY_SIZE(default0):ThisconfigurestheIn-Memorystorebysettingthisparameterforaminimumof100MB.Thedatabasemustbebouncedforthechangestotakeeffect.INMEMORY_QUERY(defaultENABLE):ThisparametercontrolswhetherthequeriesshouldbeoptimizedusingtheIn-Memorystore.INMEMORY_MAX_POPULATE_SERVERS(default0):Configuresthenumberofworkerprocesses(max)tobeusedforIn-Memorycolumnstorepopulateoperations.INMEMORY_CLAUSE_DEFAULT:ThissetsthedefaultIn-Memoryclauseorsubclause.Bydefault,thevalueoftheclauseisNULL.INMEMORY_TRICKLE_REPOPULATE_SERVERS_PERCENT:Thissetsthepercentageofworkerprocessesthatcanperformtricklerepopulation.Thedefaultvalueoftheparameteris1%.INMEMORY_FORCE(defaultDEFAULT):SettingthistoOFFrestrictstheIn-memorycolumnstorepopulation.OPTIMIZER_INMEMORY_AWARE(defaultTRUE):ThiscontrolswhethertheoptimizershouldbeawareorunawareoftheIn-Memorycolumnstore.

TheINMEMORYclauseTheobjectsrequiredtobepopulatedintheIn-MemorycolumnstorecanhavetheadditionalINMEMORYclause.TheINMEMORYattributecanbespecifiedforatable,columns,partition,materializedview,oratablespace.InadditiontotheINMEMORYclause,thereareothersub-clausesforsomeimportantaspects,suchaspopulationpriorityandcompression.

ThefollowingIn-Memorysub-clausesareappliedbydefaultalongwiththeINMEMORYclause.Tooverridethedefaultbehavior,youmustspecifythedesiredvalue.

MEMCOMPRESS:Thesub-clausedeterminesthecompressionmodeofthein-memoryobjects.Theadmissiblecompressionmodesare:

NOMEMCOMPRESS:Nocompression.MEMCOMPRESSFORDML:Compressionforfrequentlytransactionalobjects.MEMCOMPRESSFORQUERYLOW(default):Balancedcompressionmodetooptimallycompressandensurespacesavings.Enhancesthequeryperformance.MEMCOMPRESSFORQUERYHIGH:Compressionmodethatfocusesonqueryperformancebutchecksthespacesavingstoo.MEMCOMPRESSFORCAPACITYLOW:Compressionmodeforoptimalspacesavings.MEMCOMPRESSFORCAPACITYHIGH:Compressionapproachisthehighestdegreeofspacesavings.

PRIORITY:ThePRIORITYsub-clausedetermineswhetheranobject,whichismarkedasINMEMORY,canbepopulatedautomaticallyormanually.TherearefivepossiblevaluesofPRIORITYclause:

CRITICAL:CriticalpriorityobjectsarepopulatedimmediatelyafterthedatabaseisopenedorthroughtheIn-MemoryCo-ordinator(IMCO)process’stimelywake-upHIGH:AfterthepopulationofCRITICALpriorityobjectscompletesandtheIn-MemorycolumnstorehasvacantspaceMEDIUM:AfterthepopulationofCRITICALandHIGHpriorityobjectscompletesandtheIn-memorycolumnstorehasvacantspaceLOW:AfterthepopulationofCRITICAL,HIGH,andMEDIUMpriorityobjectscompletesandtheIn-memorycolumnstorehasvacantspaceNONE(Default):TheNONEprioritysegmentsarepopulatedafterthefirstfullscan

DISTRIBUTE:TheDISTRIBUTEsub-clauseisusedinclusteredenvironments(OracleDatabaseRealApplicationCluster)todistributetheobjectdataacrosstheIn-MemoryColumnStoreonalltheclusternodes.DUPLICATE:TheDUPLICATEsub-clauseisexclusivelyforthemembersoftheOracleEngineeredSystemsfamily.ItallowstheduplicationoftheIn-memorycolumnstoreacrossselectiveorallnodesoftheclusterforhighavailability.

PerformanceoptimizationsOracleDatabaseIn-Memoryfeatureisdesignedforanalyticsperformance.Theoptimizationsthataccountforoverallperformanceareasfollows:

ColumnarFormatandVectorProcessing:Thecolumnformatenablesonlytherequiredcolumntobescanned,andnotthecompleterecord.ThecolumnformatsupportsSingleInstructionMultipleData(SIMD)processing,whichhelpsinprocessingmultipledatavaluesineachCPUinstruction.PredicateevaluationandJoinoperationspushdowntotheIn-Memorycolumnstore:PredicatescanbepusheddowntotheIMcolumnstoreforevaluation.TheIn-Memorycolumnstoremakesuseofbloomfilterstojoinmultipletablestogether.TheIn-Memorystorageindexprovidesmin-maxpruningthathelpsinpreventingtheIMCUsfromscanning:PredicatescanbecheckedagainsttheIMCUheader,whichmaintainsinformationaboutminimumandmaximumvalues.IthelpsindeterminingwhethertoscanorskipanIMCU.TheevaluationofaquerypredicatecanbeminimizediftheIMCUheadersatisfiesthepredicate:IftheIMCUheaderfullyorpartiallysatisfiesthepredicatecondition,thepredicateevaluationcanbepreventedorreducedforthecolumnarunits.

In-MemoryAdvisorForlargeapplicationdatabases,choosingthemostsuitableobjectstobepopulatedintheIn-MemoryColumnStorecanbeachallenge.OracleprovidesanIn-MemoryAdvisorkittorecommendthoseobjectswhosein-memoryformatwillyieldthemaximumbenefits.ThetoolanalysesthedatabaseworkloadthroughAutomaticWorkloadRepository(AWR)andActiveSessionHistory(ASH)repositories,plancardinalities,andparallelexecution.Oncetheanalysisiscompleted,itgeneratesHTMLadvisoryreports.Thereportsprovidethelistofobjectsthatwouldbenefitthemost,whenplacedintheIn-Memorycolumnstore.

TheIn-MemoryAdvisorispartofOracleTuningPackandcanbeinstalledinOracleDatabase11.2.0.3andabove.

OracleDatabaseIn-MemorybenefitsOracleDatabase12cIn-Memoryoffersadual-formatarchitecturetosupportmixedworkloads.Anobjectcanberepresentedinrowformataswellascolumnarformat.Thecolumnarformatisread-consistentandtransactional-consistentwiththedataondisk.TheIn-MemoryfeatureisembeddednativelyintheOracleDatabase.Therefore,itissupportedonallOracleDatabase-supportedplatforms.Also,itiscompatiblewithalldatabasetechnologiessuchasRealApplicationClusters,Multitenant,HighAvailability,andExadataEngineeredSystems.

SummaryThischapterfamiliarizesthereaderswithanoverviewofOracleDatabase12c.Thischapterprovidesvaluableinsighttodatabasedevelopersintheapplicationdevelopmentspace.Also,thechaptercoversthetopratedfeaturesofOracleDatabase12c,thatisMultitenantandDatabaseIn-Memory.Thischapterwillhelpyouunderstandthebasicbuildingblocksofamultitenantcontainerdatabase.

Inthenextchapter,wewillcoverthefundamentalsofPL/SQLcodedesignthroughcursors.

Chapter3.DesigningPL/SQLCodeThestructureofaPL/SQLblockisoneoftheelementarycomponentsofPL/SQLasitshowcasesitsmodelingcapabilities.Itenablesuserstodeclarevariables,includeproceduralconstructsintheexecutablesection,andembedexceptionmanagementwithintheprogram.

AllSQLstatementswithinaPL/SQLblockareexecutedasacursor.CursorsarePL/SQLconstructsthatenableinteractionwiththedatawithinaPL/SQLblock.CursordesigningisanimportantskillinPL/SQLprogrammingasitimpactsthedataaccessparadigmandalsocodeperformance.Inthischapter,wearegoingtofocusourdiscussiononcursors.Hereisthechapteroutline:

Cursorfundamentals

1. Howcursorswork?2. Implicitandexplicitcursors3. Cursorattributes4. Cursordesignguidelines

CursorvariablesImplicitREFCURSORparameterbindingIntroductiontosubtypes

CursorstructuresInPL/SQL,acursorstructureallowstheprocessingofaSELECTstatementandaccessestheresultreturnedbythatquery.EachandeverySQLstatementinaPL/SQLblockisacursor.AcursorisahandletothechunkofthememoryareawheretheSQLstatementsareprocessedandtheresultisstored.Foradedicateddatabase,thechunkofmemoryisintheUserGlobalArea(UGA)while,forsharedserverconnections,thecursorcontextareaisallocatedintheSystemGlobalArea(SGA).

Cursorscanbeoftwotypes:

Implicitcursors:EverySQLqueryintheexecutableorexceptionsectionofaPL/SQLblockisanimplicitcursor.SELECT..INTO,SELECT..BULKCOLLECTINTO,SELECTinCURSORFORloop,INSERT,UPDATE,DELETE,andMERGEareimplicitcursors.Explicitcursors:AcursordefinedbytheuserordeveloperinthedeclarationsectionofaPL/SQLprogramisanexplicitcursor.

CursorexecutioncycleAcursorisahandlertoexecuteanSQLqueryandlivesforthelifeofasession.Oncethecurrentsessionends,thecursornolongerexists.Afterthecursorgetscreatedimplicitlyorexplicitly,itgoesthroughthefollowingstagesofexecution.

OPEN:Assoonasthecursorgetscreated,Oracleallocatesaprivateareainthesession’suserglobalarea(UGA).ThisprivateareaisusedforSQLstatementprocessing.Priortoopeningacursor,itremainsasanullpointervariable.

NoteTheinitializationparameterOPEN_CURSORSgovernsthemaximumnumberofcursors(fromthelibrarycache)thatcanbeopenedinasession.

PARSE:OraclecheckstheSQLstatementforthesyntacticalcorrectness,semantics,andprivileges.BIND:IftheSQLstatementneedsadditionalinputvaluesforprocessing,therespectiveplaceholdersarereplacedbyactualvalues.EXECUTE:TheSQLstatementisexecutedfollowingtheconventionalexecutionprocess.OraclegeneratesthehashvaluefortheSQLstatementsandplacesitinthesharedpool.OraclealsoperformslibrarycachelookuptosearchforanypastexecutionsofthesameSQL.AsuccessfullookupinthelibrarycacheavoidshardparsingofSQLstatement.Ifthehashisnotfound,anewexecutionplanisgeneratedandtheSQLisprocessed.OncetheSQLqueryisexecuted,theresultsetisplacedintheUGA.FETCH:Fetchtherecordfromtheresultsetcorrespondingtothecurrentpositionoftherecordpointer.Therecordpointerleapsforwardbyoneaftereverysuccessfulfetch.CLOSE:Thecursorhandleisclosedandtheprivatecontextareaisflushedout.

YoucanquerytheV$OPEN_CURSORviewtogetthelistofcursorsusedinthecurrentsession.LetusexecutethefollowingPL/SQLanonymousblockandchecktheentriesinV$OPEN_CURSOR:

connectscott/tiger

/*DeclareaquickPL/SQLblock*/

DECLARE

count_empNUMBER;

count_depNUMBER;

BEGIN

/*Createtwoimplicitcursors*/

SELECTCOUNT(*)INTOcount_empFROMemp;

SELECTCOUNT(*)INTOcount_depFROMdept;

END;

/


LetusquerytheV$OPEN_CURSORviewtochecktheopenandPL/SQLcachedcursors:

connsys/oracleassysdba

SELECTcursor_type,

sql_text

FROMv$open_cursor

WHEREuser_name='SCOTT'

ANDcursor_type!='DICTIONARYLOOKUPCURSORCACHED'

ORDERBYcursor_type

/

CURSOR_TYPESQL_TEXT

-----------------------------------------------------

OPENdeclarecount_recnumber;be

inselectcount(*)intocount

PL/SQLCURSORCACHEDSELECTCOUNT(*)FROMDEPT

PL/SQLCURSORCACHEDSELECTCOUNT(*)FROMEMP

Intheprecedingoutput,thetwoSELECTqueries(orimplicitcursorsofthePL/SQLblock)arePL/SQLcursor-cachedwhilethePL/SQLblockisintheOPENstate.

CursorattributesCursorattributesrevealthenecessaryinformationaboutthelastactivecursor.Cursorattributesarenotpersistedinthedatabasebutarealignedalongwiththequeryresultsetinthesessionmemory.Theseattributesare%ROWCOUNT,%ISOPEN,%FOUND,and%NOTFOUND.

Note%BULK_ROWCOUNTand%BULK_EXCEPTIONSareadditionalcursorattributesusedinbulkprocessingusingtheFORALLstatement.

Thecursorattributesarebrieflyexplainedasbelow:

%ROWCOUNT:TheattributereturnsthenumberofrowsfetchedoraffectedbytheSQLstatementinthecontextarea.Itmustbereferencedwithinthecursorexecutioncycle.Ifreferencedoutside,itraisestheINVALID_CURSORexception.%ISOPEN:TheattributeissettoTRUEifthecursoriscurrentlyopen;otherwiseitisFALSE.Programmersusethisattributeoutsidethecursorexecutioncycletocheckifthecursorisopenorclosed.%FOUND:TheattributereturnsTRUEiftherowpointerpointstoavalidrecord.Afterthelastrecordoftheresultsetisreached,theattributeissettoFALSE.%NOTFOUND:Theattributereturnsthereverseofthe%FOUNDattribute.

ImplicitcursorsEverySQLstatementintheexecutableorexceptionsectionofaPL/SQLblockisanimplicitcursor.Thedatabasetakesfullchargeofitsentireexecutioncycle,meaningthattheimplicitcursorisauto-created,auto-opened,auto-fetched,andauto-closed.AllofthesestepsaretakencarebytheOracleDatabase.SQLstatementscanbeSELECT,INSERT,UPDATE,DELETE,orMERGE,thusmakinganimplicitcursoranSQLcursor.

TheSELECTstatementforminganimplicitcursorisexpectedtoreturnexactlyonerow.Ifitfailstoreturnasinglerow,theimplicitcursorraisesTOO_MANY_ROWSorNO_DATA_FOUNDexception.Exceptionscanbetrappedandhandledwithaninformationalmessage.IfthecursorSQLisexpectedtoreturnmorethanonerow,youmustcreateanexplicitcursor.

NotethatSQL%prefixesthecursorattributesforimplicitcursors.

Cursorattributes Description

SQL%FOUNDThisattributereturnsTRUEifSELECTfetchesasinglerowortheDMLstatementaffectsaminimumofonerowinthetable.Otherwise,itissetasFALSE.

SQL%NOTFOUNDThisattributereturnsTRUEifSELECT…INTOfetchesnorowfromthedatabase.YoumightencounterNO_DATA_FOUNDexception.

SQL%ROWCOUNT

Thisattributereturns1fortheSELECTstatement.ForDMLstatements,itreturnsthenumberofrowsaffectedbytheDML.

However,theattributevalueisindependentofthetransactionstate.Ifthetransactionisrolledbacktoasavepoint,theattributevalueisnotrestoredtotheonebeforerollbackwasissued.

SQL%ISOPEN AlwaysFALSEforimplicitcursors.

NoteInOracleDatabase12c,themaximumnumberreturnedbySQL%ROWCOUNTis4,294,967,295.

ThefollowingPL/SQLblockcontainsaSELECT…INTOstatementintheexecutablesectionoftheblock:

/*EnabletheSERVEROUTPUTtoprinttheresults*/

SETSERVEROUTPUTON

/*DemonstrateimplicitcursorinPL/SQLexecutionblock*/

DECLARE

l_enameemp.ename%TYPE;

l_salemp.sal%TYPE;

BEGIN

/*Selectnameandsalaryofemployee7369*/

SELECTename,sal

INTOl_ename,l_sal

FROMemp

WHEREempno=7369;

DBMS_OUTPUT.PUT_LINE('Rowsselected:'||SQL%ROWCOUNT);

END;

/

Rowsselected:1


TheprecedingPL/SQLblockreturns1becauseempnoistheprimarykeyintheemptableandthereexistsonlyonerowagainstthevalue7369.

Nowletustrytoupdateamulti-rowdatasetintheemployeestable.ThefollowingPL/SQLblockincreasesthesalaryofemployeeswhoareworkingindepartment10:

/*EnabletheSERVEROUTPUTtoprinttheresults*/

SETSERVEROUTPUTON

/*DemonstratethecursorattributeduringDMLinaPL/SQLblock*/

BEGIN

/*Increasethesalaryofemployeesfromdepartment10*/

UPDATEemp

SETsal=sal+1000

WHEREdeptno=10;

DBMS_OUTPUT.PUT_LINE('Rowsupdated:'||SQL%ROWCOUNT);

END;

/

Rowsupdated:3


ExplicitcursorsApplicationdeveloperscanchoosetocreateacursormanually,performopenandfetchoperations,andclosethecursor.Suchcursorsareknownasexplicitcursors.Theyaremoredeveloper-friendlyastheyallowuserstomanagetheirexecutionstagesand,mostimportantly,handlemulti-rowdatasets.

AnexplicitcursorcanbeassociatedwithSELECTqueriesonly.Thecursorprototype,definedintheDECLAREsectionofaPL/SQLblock,shouldcontainavalidname.ThefollowingPL/SQLblockshowsthecursorprototypingandhandlingstagesintheexecutablesection.

DECLARE

CURSOR[CursorName][Parameters]

RETURN[Returntype]

IS

[SELECTstatement];

BEGIN

OPEN[CursorName];

FETCH…INTO[scalarorcompositevariables];

CLOSE[CursorName];

END;

IntheexecutablesectionofaPL/SQLblock,auserhastoopenacursorasOPEN[cursorname].ThedatacanbefetchedusingFETCH[cursorname]INTO[variablesorrecordvariable].Oncethefetchoperationisover,acursorcanbeclosedusingtheCLOSE[cursorname]statement.Hereiswhathappensateachofthesestages:

OPENstage:

1. Opencursor:Itallocatesaprivateworkareaintheuser’ssessionmemoryforcursorprocessing.

2. ParseSQL:ItvalidatestheSQLqueryforsyntaxandprivileges.3. BindSQL:Thisprovidesaninputvaluetothebindvariablesinthequery.4. Executethequery:ItexecutestheparsedSQLstatement.

FETCHstage:Thisstageiteratesthedatasetforeachfetchrequest.Itfetchesthedataintoblockvariables(orrecords)andincrementstherecordpointer.CLOSEstage:ThisstageclosesthecursorandreleasesthememorybacktoSGA.

Oraclesupportsparameterizationofexplicitcursors.IfaSELECTstatementhastobeexecutedwiththesamepredicatesbutdifferentvalues,itisadvisabletouseparameterizedcursors.Parameterizationofacursorisapowerfulprogrammingfeatureasitcanimprovecodingstandardsbyreducingthenumberofexplicitcursorconstructsinaprogram.

Structurally,aparameterizedcursorisanexplicitcursorwithparameters.Parametersmayormaynothavedefaultvalues.Thedevelopersuppliestheparametervaluesatthetimeofopeningthecursorintheprogrambody.Optionally,youcanalsostronglyprototypeaparameterizedcursorbyspecifyingRETURNclause.Thefollowingcursordefinitiontakesthedepartmentnumberasaparameter:

/*Cursortofetchemployeedetailsfromadepartment*/

CURSORCUR_EMP(P_DEPTNONUMBER)

IS

SELECT*

FROMemp

WHEREdeptno=P_DEPTNO;

Youcanalsospecifydefaultvalueforthecursorparameters.Forexample:


CURSORCUR_EMP(P_DEPTNONUMBERDEFAULT10)

IS

SELECT*

FROMemp


Youcanrestrictthestructureofcursorreturntypetoprotectitsaccess.


CURSORCUR_EMP(P_DEPTNONUMBER)

RETURNemp%ROWTYPE

IS

SELECT*

FROMemp


Ifyouwishtoperformatransaction(updateordelete)onacursorresultset,youcanusetheWHERECURRENTOFclauseinaDMLstatement.TheWHERECURRENTOFclauseupdatesordeletesathecurrentrowofthecursorresultset.ItismandatorytodeclarethecursorwithaSELECTFORUPDATEquerytosecurearow-levelexclusivelockonthecursorresultset.Thelockisreleasedonlyafterthetransactioniscommittedorrolledback.

Forexample,thecursorcur_inc_comminthefollowingPL/SQLblocklockstheemployeerecordsinthecursorresultset.TheUPDATEstatementmodifiestheemployee’scommission.

DECLARE

CURSORcur_inc_commIS

SELECTempno,comm

FROMemp

FORUPDATEOFcomm;

BEGIN

FORiINcur_inc_comm

LOOP

UPDATEemp

SETcomm=comm*1.2

WHERECURRENTOFcur_inc_comm;

ENDLOOP;

END;

/

NotethatyoucanreproducetheWHERECURRENTOFscenariobyusingtheROWIDpseudocolumn.

Cursorattributesplayakeyroleinaccessingtheexplicitcursorexecutioncycle.Theattributesareauto-setateachstageandthefollowingtableshowsthebehavioralflow:

Event %FOUND %NOTFOUND %ISOPEN %ROWCOUNT

BeforeOPEN Exception Exception FALSE Exception

AfterOPEN NULL NULL TRUE 0

BeforethefirstFETCH NULL NULL TRUE 0

AfterthefirstFETCH TRUE FALSE TRUE 1

BeforethenextFETCH TRUE FALSE TRUE 1

AfterthenextFETCH TRUE FALSE TRUE n+1

BeforethelastFETCH TRUE FALSE TRUE n+1

AfterthelastFETCH FALSE TRUE TRUE n+1

BeforeCLOSE FALSE TRUE TRUE n+1

AfterCLOSE Exception Exception FALSE Exception

CursorvariablesAcursorvariableenablesacursorhandlertobeassociatedwithmultipleSQLqueries.Withrespecttofunctionality,itissimilartoanexplicitcursorbutwithcertainimplementationchanges.Oneofthefundamentaldifferencesisthat,unlikeacursor,itisavariableofacursortype.Therefore,itcanpotentiallybereferencedinasimilarwaytootherprogramvariables.

Asavariable,itcanbepassedasaparametertosubprogramsorusedasareturntypeofaPL/SQLfunction.Cursorvariablescanbequitehandywhensharingresultsetsbetweentwosubprogramsorwhenaclientpullsadatasetfromthedatabase.

CursorvariablesarecreatedbydefiningavariableoftheREFCURSORtypevariableoranSYS_REFCURSORtypevariable.

NoteCursorFORloopdoesnotsupportcursorvariables

TheREFCURSORsyntaxisasfollows:

TYPE[CURSORVARIABLENAME]ISREFCURSOR[RETURN(returntype)]

Intheprecedingsyntax,theRETURNtypeofacursorvariablemustbearecordtype.Itisrequiredinstrongrefcursorstofixthereturntypeoftheresultset.

Inthefollowingexample,thePL/SQLblockdeclaresarefcursorasacursortypeandasubsequentcursorvariable.WewillopenthecursorvariablesfordifferentSELECTstatementsinseparateexecutioncycles.

/*EnabletheSERVEROUTPUTparametertoprinttheresults*/

SETSERVEROUTPUTON

DECLARE

/*DeclareaREFcursortype*/

TYPEC_REFISREFCURSOR;

/*DeclareaCursorvariableofREFcursortype*/

CURC_REF;

l_enameemp.ename%TYPE;

l_salemp.sal%TYPE;

l_deptnodept.deptno%TYPE;

l_dnamedept.dname%TYPE;

BEGIN

/*OpenthecursorvariableforfirstSELECTstatement*/

OPENcurFOR

SELECTename,sal

FROMemp

WHEREename='JAMES';

FETCHcurINTOl_ename,l_sal;

CLOSEcur;

DBMS_OUTPUT.PUT_LINE('Salaryof'||L_ENAME||'is'||L_SAL);

/*ReopenthecursorvariableforsecondSELECTstatement*/

OPENcurFOR

SELECTdeptno,dname

FROMdept

WHEREloc='DALLAS';

FETCHcurINTOl_deptno,l_dname;

CLOSEcur;

DBMS_OUTPUT.PUT_LINE('Departmentname'||l_dname||'for'||l_deptno);

END;

/

SalaryofJAMESis950

DepartmentnameRESEARCHfor20


StrongandweakrefcursortypesAREFCURSORcanbetypedeitherstrongorweak.

AREFCURSORisstrongifitsreturntypeisfixedatthetimeofdeclaration.TheRETURNclauseisusedtospecifytherecordtype.AstrongrefcursorcanbeopenedforaSELECTstatement,whichreturnsthespecifiedrecordtype.

Forexample,astrongrefcursorhavingthereturntyperecordstructureoftheemployeestable:

TYPEc_strong_rfISREFCURSORRETURNemp%ROWTYPE;

Auser-definedrecordcanbedeclaredandassignedasthereturntypeofastrongrefcursor.ThefollowingPL/SQLdeclaresalocalrecordandcursorvariableoftheREFCURSORtype.

/*Demonstratethestrongrefcursorwheretypeisalocalrecord

structure*/

DECLARE

TYPEmyrecISRECORD

(mynameVARCHAR2(10),

myclassVARCHAR2(10));

TYPEmycurISREFCURSORRETURNmyrec;

cur_varmycur;

AREFCURSORwithoutareturntypemakesitweakandSELECTstatementswithadifferentnumberofprojectedcolumnscanbeassociatedwithit.

Thecursorattributesofacursorvariablearesameasthoseofanexplicitcursor.

WorkingwithcursorvariablesBynow,youmayhaverealizedthattheexecutioncycleofacursorvariableisthesameasthatofanexplicitcursor.OnceopenedforaSELECTquery,therecordscanbefetchedbeforethecursorisclosed.

ThefollowingPL/SQLblockdeclaresastrongcursorvariablethatreturnsarecordofEMPrecordtype,butthecursorvariableisopenedforadifferentrecordstructure(DEPTrecordtype).TheblockfailstocompileandraisesaPLSexception.

/*EnabletheSERVEROUTPUTparametertoprinttheresults*/

SETSERVEROUTON

/*Demonstratetheusageofcursorvariable*/

DECLARE


l_emp_detailsemp%ROWTYPE;

l_row_numnumber;

l_random_strvarchar2(20);

/*Declarearefcursoranditsvariable*/

TYPEc_typeISREFCURSORRETURNemp%ROWTYPE;

cur_varc_type;

BEGIN

/*OpenthecursorforSELECTqueryonDEPTtable*/

OPENcur_varFOR

SELECT*

FROMdept;

/*Iteratetheresultsettodisplaythefetchcount*/

LOOP

FETCHcur_varINTOl_emp_details;

EXITWHENcur_var%NOTFOUND;

DBMS_OUTPUT.PUT_LINE('Displayresults='||cur_var%rowcount);

ENDLOOP;

/*Closethecursorvariable*/

CLOSEcur_var;

END;

/

SELECT*

*

ERRORatline16:


PLS-00382:expressionisofwrongtype


PL/SQL:SQLstatementignored.

Ifthecursorvariableisopenedforaquerywhoserecordstructurehasfewerattributesthantherefcursor’sreturnrecord,itraisestheprecedingexception.Ifthelatterhasmore,itraisesPLS-00394:wrongnumberofvaluesintheINTOlistofaFETCHstatement.

SYS_REFCURSORSYS_REFCURSORisanOraclebuilt-incursorvariabledatatypethatdeclaresaweakREFCURSORvariablewithoutdeclaringtherefpointertype.ThegenericcursorvariableisextensivelyusedwhenpassingacursorvariableasaparameterinstoredsubprogramswiththereturntypeofaPL/SQLfunction.

SYS_REFCURSORactsasacursorvariabletypeinthefollowingsyntax:

DECLARE

[Cursorvariablename]SYS_REFCURSOR;

YoucanuseSYS_REFCURSORasparametertypeinOraclesubprogramsshownbelow:

PROCEDUREP_DEMO(P_DATAOUTSYS_REFCURSOR)

IS…

...

END;

CursorvariablesasargumentsAcursorvariablecanbepassedasaformalparametertoaPL/SQLsubprogram.Subprogramscansharethepointervariabletoaccesstheresultsetsbetweenthem.

Thefollowingprocedureacceptsthedepartmentnumberasaninputanddisplaysthesalaryline-graphsortedbyjobcodes:

/*Procedureusingcursorvariableasformalparameter*/

CREATEORREPLACEPROCEDURE

p_sal_graph(p_deptNUMBER,p_emp_dataOUTSYS_REFCURSOR)

IS

/*Declarealocalrefcursorvariable*/

TYPEcur_empISREFCURSOR;

cur_salcur_emp;

BEGIN

/*OpenthelocalrefcursorvariablefortheSELECTquery*/

OPENcur_salFOR

SELECTempno,job,LPAD('*',sal/100,'.')graph

FROMemp

WHEREdeptno=P_DEPT

ORDERBYjob;

/*AssignthecursorOUTparameterwiththelocalcursorvariable*/

p_emp_data:=cur_sal;

END;

/

Procedurecreated.

/*DeclareahostcursorvariableinSQL*PLUS*/

VARIABLEM_EMP_SALREFCURSOR;

/*ExecutetheprocedureP_SAL_GRAPH*/

EXECP_SAL_GRAPH(30,:M_EMP_SAL);


/*Printthehostcursorvariable*/

PRINTM_EMP_SAL

EMPNOJOBGRAPH

-------------------------------------------------------------

7900CLERK........*

7698MANAGER...........................*

7844SALESMAN..............*

7521SALESMAN...........*

7499SALESMAN...............*

7654SALESMAN...........*

6rowsselected.

Cursorvariables–restrictionsThefollowinglistshowstherestrictionsontheusageofcursorvariables:

CursorvariablescannotbedeclaredasthepublicconstructinapackagespecificationCursorvariablescannotbesharedremotelyacrossserversCursorvariablescannotbeopenedforaSELECTFORUPDATEqueryCursorvariablesarenotphysicallystoredintheOracleDatabaseCursorvariablescannotbeassignedtoNULL

CursordesignconsiderationsThefactorsthatcanimpactthecursordesignareasfollows:

ImplicitversusExplicitcursor:IfaSELECTqueryisconfirmedtoreturnonlyonerecord,itshouldbeusedasSELECT…INTO,thusmakinganimplicitcursor.Anotherconsiderationcouldbecursorre-usabilityasimplicitcursorsarefasterthanexplicitcursors.UseParameterizedcursors:ExplicitcursordesigndependsonwhetherornotacursorwillbereusedinaPL/SQLblock.Ifthecursorqueryisexpectedtobere-runforsimilarpredicatesbutdifferentinputvalues,itcanbemadeparameterized.Parameterizedcursorsenhancethereusabilityofacursor.

Thequeryinthefollowingcursordefinitionfiltersemployeerecordsbytheirhiredate:

CURSORcurIS

SELECTename,deptno

FROMemp

WHEREhiredate<TO_DATE('01-01-1985','DD-MM-YYYY');

Ifthequerystandstobereusedwithinthesameprogram,itcanbeparameterized:

CURSORcur(p_dateDATE)IS

SELECTename,deptno

FROMemp

WHEREhiredate<p_date;

Usageofcursorvariables:AcursorvariableofREFCURSORcanbedynamicallyassociatedwithmultipleSQLqueries.

Cursordesign–guidelinesHerearesomeofthebestpracticesthatcanbefollowedduringapplicationdevelopmenttomakethebestuseofcursors.

Useaparameterizedcursoriftheexplicitcursorhastobeopenedmultipletimesfordifferentinputvalues.Youshouldfollowthecompleteexecutioncycleofthecursor.Anexplicitcursormustbeopened,fetched,andclosed.Ifitisnotclosed,thecursorresources(datastructures)arenotclearedfromtheUGA,untiltheblockexecutionisover.Exceptfor%ISOPEN,allthecursorattributesmustbereferencedwithinthecursorexecutioncycle.Italsoholdstrueforimplicitcursors.Useof%ROWTYPEmustbeencouragedtofetcharecordfromthecursorresultset.Itnotonlyreducestheoverheadofmaintainingmultiplelocalvariables,butitalsoinheritsthestructureoftheSELECTcolumnlist.Forexample,considerthefollowingcodesnippet:

/*Cursortoselectemployeeswithitsannualsalary*/

CURSORcur_deptIS

SELECTename,deptno,(sal*12)annual_sal

FROMemp;

l_cur_deptcur_dept%ROWTYPE;

Notethatthecolumnsthatarecreatedvirtuallyforcalculativepurposesmusthaveanaliasnameforreferencethroughtherecordvariable.

AcursorFORloopassociatesacursorwiththeFORloopconstruct.ItisapowerfulfeatureinPL/SQLtosimplifyandenhancecodewritingtechniques.ItimplicitlytakescareofallthestagesofcursorexecutionsuchasOPEN,FETCH,andCLOSE.

/*DemonstrateworkingwithcursorFORloop*/

DECLARE

CURSORcur_deptIS

SELECTename,deptno

FROMemp;

BEGIN

FORcINcur_dept

LOOP

…

ENDLOOP;

END;

ImplicitstatementresultsinOracleDatabase12cOracleDatabase12callowsastoredsubprogramtoreturnaresultsetimplicitlyusingtheDBMS_SQLpackage,andnotjustthroughtheREFCURSORvariable.Thenewfunctionalityisdesignedtoeasethemigrationofnon-OracleapplicationprogramstoOracle.

PriortothisenhancementinOracleDatabase12c,theonlywayaPL/SQLstoredsubprogramcouldsharearesultsetwasthroughOUTREFCURSORparameters.Later,parameterbindingwasrequiredattheclientendtoretrievetheresultsets.

Thecursorisreturnedtothecallingenvironmentusingnewoverloadedsubprograms:RETURN_RESULTandGET_NEXT_RESULT.TheGET_NEXT_RESULTcanbeusedifthecursorqueryreturnsmultipleresultsets.TheprototypeforRETURN_RESULTisasfollows:

PROCEDURERETURN_RESULT(param_resINOUTSYS_REFCURSOR,

to_clientINBOOLEANDEFAULTTRUE);

PROCEDURERETURN_RESULT(param_resINOUTINTEGER,

to_clientINBOOLEANDEFAULTTRUE);

Theparam_resparametertakeseitherthevariableofSYS_REFCURSORtypeorcursorid,whichcanberetrievedfromDBMS_SQL.OPEN_CURSOR.Theto_clientparameterdeterminesiftheresultsetcanbereturnedtotheclientprogramorcallingsubprogram.

Letusre-createtheprocedureP_SAL_GRAPH(createdearlier)usingtheenhancement.

/*Createproceduretoimplicitlyreturntheresultset*/

CREATEORREPLACEPROCEDUREp_sal_graph_12c(p_deptINNUMBER)

AS

/*DeclareaSYS_REFCURSORvariable*/

cur_salSYS_REFCURSOR;

BEGIN

/*Openthecursorfordepartment*/

OPENcur_salFOR

SELECTempno,job,LPAD('*',sal/100,'.')graph

FROMemp

WHEREdeptno=P_DEPT

ORDERBYjob;

/*UseDBMS_SQL.RETURN_RESULTtoreturnthecursor*/

DBMS_SQL.RETURN_RESULT(cur_sal);

END;

/

Nowwewillinvokethisprocedurefordepartment30inSQL*Plus.Wegetidenticalresultswithmuchreducedefforts:

/*Executetheprocedurefordepartmentid30*/

EXECp_sal_graph_12c(30);

PL/SQLprocedureissuccessfullycompleted.

ResultSet#1

EMPNOJOBGRAPH

---------------------------------------------------------

7900CLERK........*

7698MANAGER...........................*

7844SALESMAN..............*

7521SALESMAN...........*

7499SALESMAN...............*

7654SALESMAN...........*

6rowsselected.

SubtypesAsubtypeisadatatypethatgetsevolvedfromanexistingscalardatatype.Thepurposeofcreatingsubtypes,thoughnotmandatory,istocustomizetheprimarydatatypesbycontrollingcertainfeaturessuchasnullability,range,orsign.Anunconstrainedsubtypeisoftenusedinplaceofprimarydatatypestomaintainapplicationstandards.

Thesubtypeinheritsthebehaviorofitsparentbasetypeandextendsitfurtherbyadistinguishingfeature.Forexample,NATURALNisasubtypeofBINARY_INTEGER,whichpreventstheentryofnullsandnegativevalues.Similarly,SIGNTYPEpermitsonlythreefixedvalues:-1,0,or1.

Thefollowingtableshowsthebasetypesandsubtypesundereachscalardatatype:

Number Character Date/Time Boolean

NUMBER VARCHAR DATE BOOLEAN

DECIMAL/DEC VARCHAR2 INTERVAL

DOUBLEPRECISION NVARCHAR2 TIMESTAMP

FLOAT CHAR

INTEGER/INT NCHAR

NUMERIC CHARACTER

REAL LONG

SMALLINT LONGRAW

PLS_INTEGER RAW

BINARY_DOUBLE ROWID

BINARY_FLOAT STRING

BINARY_INTEGER UROWID

POSITIVE

POSITIVEN

NATURAL

NATURALN

SIGNTYPE

SubtypeclassificationSubtypescanbepredefinedoruser-defined.Pre-definedsubtypesaresystem-builtandmaintainedintheSTANDARDpackagebyOracleDatabase.HereisasmallextractfromtheSTANDARDpackagelistingthesubtypesoftheNUMBERfamily:

/*NUMBERfamilyfromSTANDARDpackage*/

typeNUMBERisNUMBER_BASE;

subtypeFLOATisNUMBER;

subtypeINTEGERisNUMBER(38,0);

subtypeINTisINTEGER;

subtypeSMALLINTisNUMBER(38,0);

subtypeDECIMALisNUMBER(38,0);

subtypeNUMERICisDECIMAL;

subtypeDECisDECIMAL;

subtypeBINARY_INTEGERisINTEGERrange'-2147483647'..2147483647;

subtypeNATURALisBINARY_INTEGERrange0..2147483647;

subtypeNATURALNisNATURALnotnull;

subtypePOSITIVEisBINARY_INTEGERrange1..2147483647;

subtypePOSITIVENisPOSITIVEnotnull;

subtypeSIGNTYPEisBINARY_INTEGERrange'-1'..1;

NoteFLOATisanunconstrainedsubtypeofNUMBER.ConstrainedsubtypessuchasNATURALandNATURALNworkmostlyonrangesandnullability.

User-definedsubtypesarecreatedontopofpredefinedtypeswithaspecificmanipulation.TheyaredefinedintheDECLAREsectionofaPL/SQLblockorsubprogram:

SUBTYPE[SUBTYPENAME]IS[PREDEFINEDTYPE][CONSTRAINT|RANGE(range

specification)]

ThefollowingPL/SQLblockdeclaresasubtypeoftheNUMBERbasetypethathasbeenconstrainedintherangeof1to10.Ifavariableofsubtypedatatypeisassignedanout-of-rangevalue,theVALUE_ERRORexceptionisraised.

DECLARE

/*Createasubtypewithvaluerangebetween1to10*/

SUBTYPEIDISBINARY_INTEGERRANGE1..10;

L_NUMID;

BEGIN

/*Assignavaluebeyondrange*/

L_NUM:=11;

END;

/

DECLARE

*

ERRORatline1:

ORA-06502:PL/SQL:numericorvalueerror

ORA-06512:atline5

TypecompatibilitywithsubtypesSubtypesareinterchangeablewiththeirbasetypesaslongasthesubtypedefinitionisnotviolated.Inthefollowingprogram,theSUBTYPEIDisaBINARY_INTEGERwithanassignedrangebetween1and10.TheprogramraisestheVALUE_ERRORexceptionifanout-of-rangevalueisassignedtothesubtypevariable:

DECLARE

/*Createasubtypewithvaluerangebetween1to10.Declarethesubtype

variable*/

SUBTYPEIDISbinary_integerrange1..10;

L_NUMID;

L_BNBINARY_INTEGER;

BEGIN

/*AssignaNUMBERvariabletoSUBTYPEvariable*/

L_NUM:=4;

L_BN:=15;

L_NUM:=L_BN;

END;

/

DECLARE

*

ERRORatline1:


ORA-06512:atline8

SummaryInthischapter,wediscussedtheimportanceofcursorstructuresinPL/SQLcode.Wecoveredtheworkingofacursor,theexecutioncycle,designconsiderations,andguidelines.TheusageofcursorscanbeimperativewhiledevelopingPL/SQLapplications.

Inthenextchapter,weshallcovercompositedatatypes,andyouwillunderstandhowcollectionscanboostPL/SQLcodeperformanceandperformdatacaching.

PracticeexerciseWhatarethepossiblereasonsthatcausetheINVALID_CURSORexceptiontooccur?

1. Cursorresultsethasnotbeenfetched.2. Thecursordoesnothaveparameters.3. Thevalueofthe%ROWCOUNTattributehasbeenreferencedafterclosingthe

cursor.4. Cursorresultsethasbeenfetchedintoanonmatchingvariable.

IdentifytheguidelinestobeconsideredwhendesigningcursorsinaPL/SQLblock:

1. Explicitcursorsmustbeusedirrespectiveofthenumberofrecordsreturnedbythequery.

2. CursorFORloopsmustbeusedasitimplicitlytakescareofOPEN,FETCH,andCLOSEstages.

3. Cursordatamustbefetchedasarecord.4. UseROWNUMtoindextherecordsinthecursorresultsets.

WhileprocessingDMLsasimplicitcursorsinaPL/SQLexecutableblock,implicitcursorattributescanbeusedanywhereintheblock.

1. True.2. False.

Fromthefollowingoptions,identifythetwocorrectstatementsabouttheREFCURSORtype?

1. Refcursorsarereferencepointerstocursorobjects.2. REFCURSORtypescanbedeclaredinthepackagespecification.3. SYS_REFCURSORisastrongrefcursortype.4. Acursorvariablecannotbeusedasargumentsinstoredsubprograms.

TheRETURNtypeforarefcursorcanbedeclaredusing%TYPE,%ROWTYPE,orauser-definedrecord.

1. True.2. False.

Whichtwostatements,amongthefollowing,aretrueaboutcursorvariables?

1. CursorvariablescanprocessmorethanoneSELECTstatement.2. Acursorvariablecanbepassedasprogramargumentsacrosssubprogramsand

eventotheclientendprograms.3. Acursorvariablecanbedeclaredasapublicconstructinthepackage

specification.

4. Cursorvariablescanbestoredinadatabaseasdatabasecolumns.

Similartostaticexplicitcursors,cursorvariablescanalsobeopenedintheFORloop

1. True.2. False.

Whichofthefollowingistruewhilecreatingsubtypesfromatablerecordstructure?

SUBTYPE[Name]IS[TABLE]%ROWTYPE

1. Thesubtypeinheritscompletecolumnstructureoftherecordstructure.2. Thesubtypeinheritsthedefaultvaluesofthedatabasecolumnsintable.3. Thesubtypeinheritstheindexinformationofthedatabasecolumns.4. ThesubtypeinheritsnoneexcepttheNOTNULLconstraintinformationofthe

databasecolumns.

Chapter4.UsingCollectionsAcollectionisasingle-dimensionalstructureofhomogeneouselements.Behaviorallyspeaking,itisquitesimilartoanarrayandaliststructureavailableinotherthirdgenerationlanguages.FirstintroducedinOracle7asPL/SQLtables,Oracle8irebrandedcollectionsasIndex-bytables.Oracle8ialsointroducedpersistentcollectiontypes,namelynestedtablesandvarrays.OracleDatabase9irenamedIndex-by-tablestoassociativearrays.

OracleDatabaseoffersawidescopeofusabilityofcollectionsinPL/SQLprogramming.Thelanguagesemanticsnotonlyallowyoutocreateandmaintaincollections,butalsoprovidesmultiplemethodsforarrayoperations.ThischapterhelpsyoutounderstandthecollectiontypesinOracleand,mostimportantly,whichtypessuitagivenproblem.Thechapteroutlinelookslikethis:

Anintroductiontocollections

CategorizationSelectionofanappropriatecollectiontype

AssociativearraysNestedtablesVarraysPL/SQLcollectionmethodsManipulatingcollectionelementsCollectiondesignconsiderations

IntroductiontocollectionsAcollectionisanarraylikehomogeneoussingle-dimensionalstructure,whichholdsasetofelementsofsimilardatatype.Eachcellinacollection,andhence,eachelement,isuniquelyidentifiedbyitspositionindexorthesubscript.TheelementorthevaluecontainedinacellcanbeofavalidSQLdatatypeorauser-definedtype.Therearethreetypesofcollections:associativearray;nestedtable;andvarray.

Acollectioncanbeboundedorunboundedonthebasisofit’scollectionsize.Boundedcollectionshaveafixednumberofelements,asinarrays.Unboundedcollectionscanhaveanynumberofelements.Varraysareboundedcollectionswhiletheassociativearraysandnestedtablesareunbounded.

Onthebasisofpersistenceinthedatabase,acollectioncanbeeitherapersistentornon-persistentcollection.ApersistentorSQLcollectioncaneitherbecreatedintheOracleDatabaseschemaordeclaredwithinthePL/SQLblock.APL/SQLornon-persistentcollectionisdeclaredinaPL/SQLblockonly.Anestedtableandavarrayarepersistentcollections.Anassociativearrayisalwaysanon-persistentcollection.

CollectiontypesAnassociativearrayisanon-persistentunboundedcollectionwhichmeansthatanassociativearraycannotbecreatedintheOracleDatabaseschema,butlocallydeclaredwithinthedeclarativesectionofaPL/SQLblock.

AnestedtableisapersistentcollectionofhomogeneouselementsthatcanbecreatedinadatabaseasaschemaobjectaswellasdeclaredwithinaPL/SQLblock.Anestedtablebeinganunboundedcollection,hasnolimitonthenumberofelements.

Avarrayisasingle-dimensionalhomogeneouscollectionthatcanbecreatedinadatabaseaswellasinPL/SQL.Beingaboundedcollection,itcanholdonlyafixednumberofelements.

AssociativearraysAssociativearraysinOraclearesimilartoconventionallistsinotherprogramminglanguages.AnassociativearrayisanunboundedarrayofcellsandalwaysdefinedinthedeclarativesectionofaPL/SQLprogram.Whileacellisidentifiedbyanindexofnumberorstringtype,itcanholdavalueofascalardatatypeoruser-definedcompositetype.

ThesyntaxtodeclareanassociativearrayinaPL/SQLblockisasfollows:

TYPE[COLLNAME]ISTABLEOF[ELEMENTDATATYPE]NOTNULL

INDEXBY[INDEXDATATYPE]

Inthesyntax,the[INDEXDATATYPE]signifiesthedatatypeofanarraysubscript.ItcanbeBINARY_INTEGER,PLS_INTEGER,POSITIVE,NATURAL,SIGNTYPE,orVARCHAR2.ThedatatypesthatarenotsupportedasindextypesareRAW,NUMBER,LONG-RAW,ROWID,andCHAR.

The[ELEMENTDATATYPE]canbeoneofthefollowing:

PL/SQLscalardatatype:NUMBER(alongwithitssubtypes),VARCHAR2(anditssubtypes),DATE,BLOB,CLOB,orBOOLEANInferreddata:Thedatatypeinheritedfromatablecolumn,cursorexpressionorpredefinedpackagevariableUser-definedtype:Auser-definedobjecttypeorcollectiontype

Herearesomesampledeclarationsofanassociativearray:

/*AssociativearrayofCLOBindexedbyanumber*/

TYPEclob_tISTABLEOFCLOBINDEXBYPLS_INTEGER;

/*Arrayofemployeeidsindexedbytheemployeenames*/

TYPEempno_tISTABLEOFemp.empno%TYPENOTNULL

INDEXBYemp.ename%type;

ThefollowingPL/SQLprogramdeclaresanassociativearrayofsomeelementswithastringtypesubscript.TheFIRSTandNEXTcollectionmethodsarediscussedindetailinthePL/SQLcollectionmethodssectioninthischapter:

/*EnabletheSERVEROUTPUTontodisplaytheoutput*/

SETSERVEROUTPUTON


DECLARE

/*Declareanassociativearrayandalocalvariableofcollectiontype*/

TYPEstring_asc_arr_tISTABLEOFNUMBER

INDEXBYVARCHAR2(10);

l_strstring_asc_arr_t;

l_idxVARCHAR2(10);

BEGIN

/*Assignthetotaldaysineachquarter*/

l_str('JAN-MAR'):=90;

l_str('APR-JUN'):=91;

l_str('JUL-SEP'):=92;

l_str('OCT-DEC'):=93;

l_idx:=l_str.FIRST;

WHILE(l_idxISNOTNULL)

LOOP

DBMS_OUTPUT.PUT_LINE('Valueat'||l_idx||'is'||l_str(l_idx));

l_idx:=l_str.NEXT(l_idx);

ENDLOOP;

END;

/

ValueatAPR-JUNis91

ValueatJAN-MARis90

ValueatJUL-SEPis92

ValueatOCT-DECis93


Similarly,thefollowingPL/SQLblockpopulatesanassociativearrayofstringvalueswithrandomvalues:


SETSERVEROUTPUTON

/*StartthePL/SQLBlock*/

DECLARE

/*Declareanarrayofstringindexedbynumericsubscripts*/

TYPErandom_tISTABLEOFVARCHAR2(12)INDEXBYPLS_INTEGER;

l_randomrandom_t;

BEGIN

/*InsertthevaluesusingaFORloop*/

FORIIN1..100

LOOP

l_random(I):=DBMS_RANDOM.STRING('X',10);

ENDLOOP;

/*Displaythevaluesrandomly*/

DBMS_OUTPUT.PUT_LINE(l_random(5));



END;

/

5NHU5R5UMU

98P7NUDZZB

E6AG6TR07S


Thefeaturesofassociativearraysareasfollows:

Anassociativearraycanbesparse,meaningtheindexneednotbeconsecutive.Beinganon-persistentcollection,itcannotparticipateinDMLtransactions.

However,elementsofanassociativearraycanbeusedintheDMLwithinaFORALLstatement.Itcanbepassedasanargumenttootherlocalsubprograms.SortingofanassociativearraydependsontheNLS_SORTparameter.Anassociativearraydeclaredinapackagespecificationbehavesasapersistentarrayinasession.

NestedtablesAnestedtableisapersistentSQLcollectionthatisusedasalisttoholdelementsofthesamedatatype.ItcanalsobecreatedinthedatabaseanddefinedinaPL/SQLprogram.Itisanunboundedcollectionandtheuserdoesn’thavetomaintainthecellindex.Oracleautomaticallyassignsthecellindexas1tothefirstcellandmovesonwardsincrementally.Anestedtablecollectiontypeinitiallystartsoffasadensecollectionbutitbecomessparseduetodeleteoperations.

NoteAdensecollectionreferstoacollectionthatistightlypopulatedwhichmeansnoemptycellsbetweenthelowerandupperindexesofthecollection.Adensecollectionmaybecomesparsebyperformingdeleteoperations.

Whenanestedtableiscreatedasaschemaobjectinthedatabase,itcanbereferencedinaPL/SQLblockasavariableparameter.Acolumnofnestedtabletypescanbeincludedinatable.Anattributeofnestedtabletypescanexistinanobjecttype.Inadatabaseschema,anestedtablecanbedeclaredusingtheCREATETYPE…statement:

CREATE[ORREPLACE]TYPEtype_nameISTABLEOF[element_type][NOTNULL];

/

Intheprecedingsyntax,[element_type]canbeanSQL-supportedscalardatatype,adatabaseobjecttype,oraREFobjecttype.TheunsupportedelementtypesareBOOLEAN,LONG,LONG-RAW,NATURAL,NATURALN,POSITIVE,POSITIVEN,REFCURSOR,SIGNTYPE,STRING,PLS_INTEGER,SIMPLE_INTEGER,BINARY_INTEGERandallothernon-SQLsupporteddatatypes.

WhenanestedtableisdeclaredinaPL/SQLprogram,itbehavesasaone-dimensionalarraywithoutanyindextypeorupperlimitspecification.Itcanbereferencedonlywithintheprograminwhichitisdeclared.AtabletypedefinitioninaPL/SQLblockfollowsthebelowsyntax:

DECLARE

TYPEtype_nameISTABLEOFelement_type[NOTNULL];

Theelement_typeisaprimitivedatatype(exceptcursorvariables)orauser-definedtype.

ModifyanddropanestedtableobjecttypeToincreasetheprecisionofnestedtableelements,usetheALTERTYPEcommandwithCASCADEorINVALIDATEoptions:

ALTERTYPE[typename]MODIFYELEMENTTYPE[modifiedelementtype]

[CASCADE|INVALIDATE];

TheCASCADEandINVALIDATEoptionsdeterminewhetherthecollectionalterationhastocascadeorinvalidatethedependents.

ThenestedtabletypecanbedroppedusingtheDROPcommand,asshowninthefollowingsyntax(notethattheFORCEkeyworddropsthetypeirrespectiveofitsdependents):

DROPTYPE[collectionname][FORCE]

DesignconsiderationsofanestedtableAsadatabasedeveloper,youmustunderstandthefactorsthatinfluencenestedtabledesignandlayout.Forinstance,retrievalofanout-of-linestorednestedtablestructurealongwiththetablecolumnscouldpotentiallyimpactthequerydesign.Thissectiontalksaboutkeyaspectsthatshouldbeconsideredduringnestedtabledesign.

NestedtablestorageOraclemaintainsaseparatestoragetabletostorethenestedtabledata.Thisstoragetableisintegrallyconnectedtotheparenttablethroughasystem-generated16-bytevalueknownasNESTED_TABLE_ID.Thisvalueisusedtocorrelatetheparentrowvalueandtheconnectedstoragetablerows.

Nestedtableinanindex-organizedtableAnestedtablewithaprimarykeybehavesasanindex-organizedtable(IOT).IftheprimarykeyisconstitutedwithNESTED_TABLE_ID,theparentandchildrowsareclusteredtogether,whichhelpsinfastretrievalofchildrows.Inaddition,nestedtablecompressioncanbeenabledusingtheCOMPRESSclause.Anestedtableincompressedmodepreventstherepetitionofaparentkeyforasetofchildrowsinthestoragetable,thusoptimizingthespaceconsumption.Thisformatoforganizationinnestedtablescanbebeneficialwhentheapplicationretrievesanestedtableasacompleteunit.

Alternatively,indexingNESTED_TABLE_IDinthestoragetablecanalsoacceleratetheaccessandretrievalofchildrows.

NestedtablelocatorsNestedtablelocatorsareusefulwhenaparentrowcorrelatestoalargesetofchildrows.Insteadofperformingjoinsandreturninglargedatasets,Oracleretrievesalocatorthatcanbeusedtoaccessthechildrecordswheneverrequired.Therearetwowaystofetchthecollectiontypeasalocation:

SpecifyRETURNASLOCATORinthestorageclauseUsetheNESTED_TABLE_GET_REFShintintheSELECTstatement

NestedtableastheschemaobjectThefollowingexampledemonstratesthecreationofanestedtabletypeinthedatabaseandusingitasacolumndatatypeinatable.TheobjecttypeNT_SCORESrecordsthescoresofabatsmaninacrickettournament:

/*Createthenestedtableinthedatabase*/

CREATETYPEnt_scoresASTABLEOFNUMBER;

/

Typecreated.

ThemetadatainformationforNT_SCORESisavailableintheUSER_TYPESandUSER_COLL_TYPESdictionaryviews:

/*Selectquerytogetnestedtablemetadataascollectiontype*/

SELECTtype_name,typecode,type_oid

FROMUSER_TYPES

WHEREtype_name='NT_SCORES'

/

TYPE_NAMETYPECODETYPE_OID

--------------------------------------------------------------

NT_SCORESCOLLECTION1218C13A817D0D9FE0530F02000A6119

NotethattheTYPECODEvalueshowsthetypeoftheobjectinthedatabaseanddifferentiatescollectiontypesfromuser-definedobjecttypes.Let’snowquerytheUSER_COLL_TYPESdictionaryviewtoquerythecollectiontypeandelementtypeofthenestedtable:

SELECTtype_name,coll_type,elem_type_name

FROMuser_coll_types

WHEREtype_name='NT_SCORES'

/

TYPE_NAMECOLL_TYPEELEM_TYPE_NAME

---------------------------------------------

NT_SCORESTABLENUMBER

TheCREATETABLEstatementcreatesatablewithacolumnoftheNT_SCOREStabletype.Althoughanestedtabletypecolumninatableresemblesatablewithinatable,Oraclecreatesaseparatestoragetablefromtheparenttable.TheNESTEDTABLE[Column]STOREAS[storagetable]clausespecifiesthestoragetableforthenestedtabletypecolumn.Atthetimeofrecordcreation,thedatainthestoragetableisconnectedtotherowintheparenttablethrougharowidentifier:

CREATETABLEt_bat_scores

(nameVARCHAR2(30),

posNUMBER,

scoreNT_SCORES)

NESTEDTABLEscoreSTOREASnt_scores_st

/

Tablecreated.

Bydefault,thestorageoptionsforthestoragetablearethesameasthatofthemaintable.Ifyouwantthestoragetableonadifferenttablespace,youcanspecifytheTABLESPACEclausealongsidetheNESTEDTABLEclause:

NESTEDTABLEscoreSTOREASnt_scores_st

(TABLESPACEnt_tbs_storage)

/

IfyoumovetheparenttabletoadifferenttablespaceusingtheALTERTABLE…MOVEstatement,thenthestoragetabledoesn’tmoveunlessyouexplicitlymovethestoragetableasfollows:

ALTERTABLEnt_scores_stMOVETABLESPACEnt_tbs_storage

/

OperationsonanestedtabletypecolumnIntermsofdatacontainedinacolumn,thenestedtabletypecolumnstorestheobjecttypeinstance,insteadofscalardatavalues.Thestructureoftheobjecttypeinstancemustbenotedwhileinsertingtherecordsinthetableandqueryingthedatafromthetable.

Thissectiontakesyouthroughthedifferentoperationsonthenestedtabletypecolumnandtheobjecttypeinstance.

Createanestedtableinstance

Let’sinserttherunsscoredbythefirsttwobatsmenoftheteaminthelastfiveinnings.Notetheobjecttypeinstancecanbeinsertedinanestedtabletypecolumnusingacollectiontypeconstructor.Itisadefaultconstructorwiththesamenameasthecollectionandallmemberattributes:

INSERTINTOt_bat_scores(name,pos,score)VALUES

('Duckworth',1,nt_scores(115,37))

/


('Duckworth',2,nt_scores(71,29,13))

/


('Lewis',1,nt_scores(34,65,23))

/


('Lewis',2,nt_scores(0,1))

/

commit

/

Queryingthetabledata,youcanseethenestedvaluesthatistheinstancesofnestedtables:

SELECT*

FROMt_bat_scores

/

NAMEPOSSCORE

-----------------------------------------------------------

Duckworth1NT_SCORES(115,37)

Duckworth2NT_SCORES(71,29,13)

Lewis1NT_SCORES(34,65,23)

Lewis2NT_SCORES(0,1)

Inthenextinnings,DuckworthopensatNo.1positionandscores125,whileLewisscores45atNo.2position.Youwouldwanttoupdatetheexistingobjectinstancesandnotcreateaduplicateentryforthebatsmen.Oracleallowsthepiecewiseinsertsandupdatesontheobjectinstances.ThepiecewisescoreisinsertedusingthefollowingINSERTstatement:

INSERTINTOTABLE(SELECTscore

FROMt_bat_scores

WHEREname='Duckworth'

ANDpos=1)

VALUES(125)

/

INSERTINTOTABLE(SELECTscore

FROMt_bat_scores

WHEREname='Lewis'

ANDpos=2)

VALUES(45)

/

COMMIT

/

Afterthenewscoresareupdatedinthetable,theobjectinstanceslooklikethis:

SELECT*

FROMt_bat_scores

/

NAMEPOSSCORE

------------------------------------------------------------





Duetoashortrun,Duckworthlosesarunandhisscoreisnow124.Thischangehastoreflectbackinthetable.ThefollowingUPDATEstatementhelpsyouperformpiecewiseupdates.ThefollowingSELECTqueryverifiesthevalueupdate:

UPDATETABLE(SELECTscore

FROMt_bat_scores

WHEREname='Duckworth'andpos=1)P

SETP.COLUMN_VALUE=124

WHEREP.COLUMN_VALUE=125

/

SELECT*

FROMt_bat_scores

/

NAMEPOSSCORE

--------—---------





Queryinganestedtablecolumn

Whenatablewithanestedtablecolumnisqueried,thenestedtablecolumnappearsasaninstanceofnestedtableobjecttype.Wealreadysawthisinactioninthelastsection.

TheTABLEexpressioncanbeusedtounnestoropentheinstanceanddisplaythedatainrelationalformat.TheTABLEexpressionisusedtoaccesstheattributesofnestedtabletype.Oracleimplicitlyjoinstheparentrowwiththenestedtablerowinthequeryoutput:

SELECTT.name,T.pos,T1.column_value

FROMt_bat_scoresT,TABLE(T.score)T1

/

NAMEPOSCOLUMN_VALUE

---------------------------------

Duckworth1115

Duckworth137

Duckworth1124

Duckworth271

Duckworth229

Duckworth213

Lewis134

Lewis165

Lewis123

Lewis20

Lewis21

Lewis245

12rowsselected.

IntheprecedingSELECTquery,COLUMN_VALUEisanOraclepseudo-columnthatisusedintheSELECTqueriestosignifythenestedtablecolumnwithnoattributename.

NestedtablecollectiontypeinPL/SQLInPL/SQL,anestedtablecanbedeclaredanddefinedinthedeclarationsectionofaPL/SQLblockasalocalcollectiontype.ThePL/SQLvariableofnestedtabletypemustbeinitializedbeforeusingitintheprogrambody.OracleraisestheexceptionORA-06531:Referencetouninitializedcollectionifanuninitializedcollectiontypevariableisaccessedintheprogrambody.

Collectioninitialization

WhenusedinaPL/SQLprogram,thevariablesofnestedtableorvarraycollectiontypesmustbeinitialized.Associativearraysarelocalnon-persistentarrays,sonoinitializationisrequiredforthem.Thissectionhasbeenincludedtogiveabriefdescriptionofcollectioninitializationmethods:

Initializeacollectioninthedeclarativesectionbyusingthedefaultconstructor:


DECLARE

TYPEcoll_nt_tISTABLEOFNUMBER;

/*Collectionvariableinitializationusingadefaultconstructor*/

L_LOCAL_VAR1coll_nt_t:=coll_nt_t(10,20);

/*collectionvariableinitializationwithanemptycollection*/

L_LOCAL_VAR2coll_nt_t:=coll_nt_t();

BEGIN

…

…

END;

InitializeacollectionintheexecutablesectionthroughassignmentortheSELECT…INTOstatement:

Intheexecutablesection,aSELECTstatementcanpullacollectioninstance(ofthesamecollectiontype)intothelocalcollectionvariable.ThismethodofcollectioninitializationispermissibleonlywhenthecollectiontypeexistsasaschemaobjectandisusedtodeclareaPL/SQLvariable.

Inourearlierillustrations,nt_scoresisanestedtableinthedatabase.Letususethesametypetodeclarealocalcollectionvariable:


DECLARE

l_loc_numnt_scores;

l_loc_idxnt_scores;

BEGIN

/*InitializingthecollectionvariablewithSELECT…INTO*/

SELECTnumINTOl_loc_num

FROMtab_use_nt_col

WHEREid=1;

/*Initializingthecollectionvariablewithanassignment*/

l_loc_idx:=l_loc_num;

END;

/

ThefollowingPL/SQLblockdeclaresanestedtableinthedeclarativesection.Observethescopeandvisibilityofthecollectionvariable.NotethattheCOUNTmethodhasbeenusedtodisplaythearrayelements:

/*EnabletheSERVEROUTPUTtodisplaytheresults*/

SETSERVEROUTPUTON


DECLARE

/*Declarealocalnestedtablecollectiontype*/

TYPEnt_localISTABLEOFNUMBER;

l_arraynt_local:=nt_local(10,20,30);

BEGIN

/*UseFORlooptoparsethearrayandprinttheelements*/

FORIIN1..l_array.COUNT

LOOP

DBMS_OUTPUT.PUT_LINE('Showing'||i||'value:'||l_array(I));

ENDLOOP;

END;

/

Showing1value:10

Showing2value:20

Showing3value:30


QueryingthenestedtablemetadataAsacollectiontype,thenestedtable’smetadatacanbequeriedfromtheUSER_TYPESorUSER_COLL_TYPESviews.Forthenestedtabletypecolumninatable,Oracle’sUSER_NESTED_TABLESandUSER_NESTED_TABLE_COLSdatadictionaryviewsmaintaintheinformationoftheparentandthenestedtables.TheUSER_NESTED_TABLESstaticviewmaintainstheinformationaboutthemappingofanestedtablecollectiontypewithitsparenttable.

ThefollowingSELECTstatementonUSER_NESTED_TABLESqueriesthedetailsofthestoragetableassociatedwiththeparenttable:

SELECTparent_table_name,

parent_table_column,

table_name,

table_type_name,

storage_spec

FROMuser_nested_tables

WHEREparent_table_name='T_BAT_SCORES'

/

PARENT_TABLE_NAPARENT_TABTABLE_NAMETABLE_TYPESTORAGE_SPEC

-----------------------------------------------------------------

T_BAT_SCORESSCORENT_SCORES_STNT_SCORESDEFAULT

Letusnowquerythenestedstoragetableintheprecedingdictionaryviewtolistallitsattributes:

SELECTCOLUMN_NAME,DATA_TYPE,DATA_LENGTH,HIDDEN_COLUMN

FROMuser_nested_table_cols

wheretable_name='NT_SCORES_ST'

/

COLUMN_NAMEDATA_TYPDATA_LENGTHHID

------------------------------------------------------------

NESTED_TABLE_IDRAW16YES

COLUMN_VALUENUMBER22NO

TheCOLUMN_VALUEattributeisthedefaultpseudo-columnofthenestedtableastherearenonamedattributesinthecollectionstructure.Theotherattribute,NESTED_TABLE_ID,isahidden,unique,16-byte,system-generatedrawhashcode,whichstorestheparentrowidentifieralongsidethenestedtableinstancetodistinguishtheparentrowassociation.Itsvalueisthesameasthesystemsuppliedid(SYS_NCXXXX$)valueintheparenttable.

NestedtablecomparisonfunctionsOracleprovidesSQLfunctionsthatcanbeappliedtonestedtablesformultisetpurposes.Thefunctionsarebrieflydescribedinthefollowingtable:

Collectionfunction Description

SET Returnsdistinctelementsofanestedtable

CARDINALITY Returnsthecountofelementsinanestedtable

[NOT]SUBMULTISET ReturnsTRUE,ifanestedtableisasubsetoftheothernestedtable

POWERMULTISET(SQLonly) Generatesallpossiblenon-emptysub-multisetsfromaninputcollection.Maximumcardinalityis32.

POWERMULTISET_BY_CARDINALITY

(SQLonly)Generatesthenon-emptysub-multisetsfromaninputcollection,filteredbythegivencardinality.

MultisetoperationsonnestedtablesThesetoperators(UNION,INTERSECT,andMINUS)inSQLareusedtocombinetheresultsfrommorethanoneSQLqueryintoasingleresultset.OracleDatabase10gintroducedmultisetoperatorstoallowsetoperationsonnestedtables.Amultisetoperationcombinesmorethanonenestedtablesandreturnsacollectionresultingfromamultisetoperator.

Themultisetoperationsaddauniqueandexclusivecapabilitytonestedtables.Insteadoffollowingthetrivialloop-through-collectionapproachtorow-comparetwocollectionsforcommonordifferenceelements,youcannowcompareacollectionasanobject.

NoteMultisetoperatorsareavailableinPL/SQL,andSQLtoo.

Themultisetoperatorsarelistedasbelow:

MULTISETUNION[ALL|DISTINCT]:combinestwonestedtablesofthesametypeandreturnsanestedtablecontainingtheelementsfromboththeinputcollections.YoucanuseALLorDISTINCTtoalloworpreventduplicationofelements.ALListhedefault.MULTISETINTERSECT[ALL|DISTINCT]:combinestwonestedtablesofthesametypeandreturnsanestedtablecontainingtheelements,whicharecommoninthetwonestedtables.IfyouusetheDISTINCToption,Oracleremovestheduplicatevaluesfromthefinalresultset.MULTISETEXCEPT[ALL|DISTINCT]:workswithtwonestedtablesofthesametypeandreturnsanestedtablecontainingtheelements,whicharepresentinthefirstbutnotinthesecond.IfyouusetheDISTINCToption,Oracleremovesthecommonelements.

TipFormultisetoperations,theinputnestedtablesshouldbeofthesametypewithcomparableelements.Ifyouareworkingwithcomplexcollectiontypesthatisanestedtablewithcomplexattributes,youmustusetheMAPordermethodtoenablesortingofthecollectionelements.Theresultofamultisetoperationisofthesamecollectiontypeastheoperands.

ThefollowingPL/SQLblockdemonstratestheusageofmultisetoperators.

/*CreateanestedtablecollectionobjectinSCOTTschema*/

CREATEORREPLACETYPElist_of_lettersASTABLEOFVARCHAR2(1);

/

/*Enabletheserveroutput*/

SETSERVEROUTPUTON


DECLARE

/*Declaretwolocalcollectionvariables*/

str1list_of_letters:=list_of_letters('O','R','A','C','L','E');

str2list_of_letters:=list_of_letters('D','A','T','A','B','A','S','E');

/*Localproceduretoprintthecollectionelements*/

PROCEDUREprint_nt(strINlist_of_letters)

IS

BEGIN

FORiin1..str.COUNT

LOOP

DBMS_OUTPUT.PUT(str(i)||'.');

ENDLOOP;

DBMS_OUTPUT.NEW_LINE;

DBMS_OUTPUT.PUT_LINE(RPAD('',50,'-'));

ENDprint_nt;

BEGIN

/*Multisetintersectoperation*/

DBMS_OUTPUT.PUT('MULTISETINTERSECT=>');

PRINT_NT(str2MULTISETINTERSECTstr1);

/*Multisetintersectdistinctoperation*/

DBMS_OUTPUT.PUT('MULTISETINTERSECTDISTINCT=>');

PRINT_NT(str2MULTISETINTERSECTDISTINCTstr1);

/*Multisetunionoperation*/

DBMS_OUTPUT.PUT('MULTISETUNION=>');

PRINT_NT(str1MULTISETUNIONstr2);

/*Multisetuniondistinctoperation*/

DBMS_OUTPUT.PUT('MULTISETUNIONDISTINCT=>');

PRINT_NT(str1MULTISETUNIONDISTINCTstr2);

/*Multisetexceptoperation*/

DBMS_OUTPUT.PUT('MULTISETEXCEPT=>');

PRINT_NT(str2MULTISETEXCEPTstr1);

/*Multisetexceptdistinctoperation*/

DBMS_OUTPUT.PUT('MULTISETEXCEPTDISTINCT=>');

PRINT_NT(str2MULTISETEXCEPTDISTINCTstr1);

END;

/

MULTISETINTERSECT=>A.E.

-------------------------------------------------

MULTISETINTERSECTDISTINCT=>A.E.

-------------------------------------------------

MULTISETUNION=>O.R.A.C.L.E.D.A.T.A.B.A.S.E.

-------------------------------------------------

MULTISETUNIONDISTINCT=>O.R.A.C.L.E.D.T.B.S.

-------------------------------------------------

MULTISETEXCEPT=>D.T.A.B.A.S.

-------------------------------------------------

MULTISETEXCEPTDISTINCT=>D.T.B.S.

-------------------------------------------------


VarrayOracleDatabase8iintroducedvarraysasamodifiedformatofanestedtable.Thevarrayorvariablesizearrayisquitesimilartonestedtablesbutboundedinnature.Thevarraydeclarationincludesthecountofelementsthatavarraycanaccommodate.Theminimumvarrayindexis1,thecurrentsizeisthetotalnumberofelements,andthemaximumlimitisthevarraysize.Atanymoment,thecurrentsizecannotexceedthemaximumlimit.Varraysareappropriatelyusedwhenyouknowthemaximumnumberofelementsinacollectionstructure.

Likenestedtables,varrayscanbecreatedinthedatabaseasschemaobjectsaswellasinaPL/SQLblock.Whencreatedinthedatabaseasaschemaobject,varrayscanbereferencedinPL/SQLprogramunitsasvariables,parametersandfunctionreturntypes.Atablecanhaveacolumnofavarraytype.Anobjecttypecanhaveanattributeofavarraytype.Thesyntaxforvarrays,whendefinedasadatabasecollectiontype,isasfollows:

CREATE[ORREPLACE]TYPEtype_nameIS{VARRAY|VARYINGARRAY}(size_limit)

OFelement_type

Whenavarraytypecolumnisincludedinatable,itisstoredinlinewiththecorrespondingrowintheparenttable.Therefore,thereisnoneedtohaveaseparatestoragetable.Ifthevarraycolumnsizeexceeds4kilobytes,Oraclefollowstheout-of-linestoragemechanismandstoresthevarrayasanLOB.

NoteThein-linestoragemechanismofvarrayshelpsOracletoreducethediskI/Os.

WhendeclaredinaPL/SQLblock,avarraycanbereferencedwithinthecurrentblockonly.InPL/SQL,varrayscanbedeclaredasfollows:

DECLARE

TYPEtype_nameIS{VARRAY|VARYINGARRAY}(size_limit)OF

element_type[NOTNULL];

Inthesyntax,size_limitdeterminesthemaximumcountofelementsinthearray.Ifthevarraysizehastobemodifiedaftercreation,followthisALTERTYPEsyntax:

ALTERTYPE[varrayname]MODIFYLIMIT[newsize_limit]

[INVALIDATE|CASCADE];

NoteThevarraysizecanonlybeincreasedbyusingtheALTERTYPE…MODIFYstatement.Evenifthecurrentmaximumsizeisnotutilized,Oracledoesn’tallowtheripping-offofavarraysize.Ifyoutrytoreducethevarraysize,OracleraisesthecompilationerrorPLS-00728:thelimitofaVARRAYcanonlybeincreasedandtoamaximum2147483647.

TheINVALIDATEandCASCADEoptionssignifytheinvalidationorpropagationeffectonthedependentobjectsasaresultofthetypealteration.

Note

UsetheDROPcommandtodropavarraytypefromthedatabase:DROPTYPE[varraytypename][FORCE]

VarrayasaschemaobjectThefollowingexampledemonstratestheusageofavarrayasaschemaobject.Thevarraycapturestheannualproductionvaluesrecordedbyageographyfortheyears.

Let’screateavarrayofacompositeobjecttype:

CREATEORREPLACETYPEot_num_2ASOBJECT

(strVARCHAR2(25),

numNUMBER

);

/

CREATEORREPLACETYPEv_geo_prodASVARRAY(5)OFot_num_2;

/

Formetadatainformation,we’llquerytheUSER_TYPESandUSER_COLL_TYPESviews:

SELECTtype_name,typecode,type_oid

FROMUSER_TYPES

WHEREtype_name='V_GEO_PROD'

/

TYPE_NAMETYPECODETYPE_OID

---------------------------------------------------------

V_GEO_PRODCOLLECTION122DC43ECA0412EEE0530F02000AC98A

SELECTtype_name,coll_type,elem_type_name

FROMuser_coll_types

WHEREtype_name='V_GEO_PROD'

/

TYPE_NAMECOLL_TYPEELEM_TYPE_NAME

----------------------------------------------------------------

V_GEO_PRODVARYINGARRAYOT_NUM_2

ThefollowingCREATETABLEscriptcreatesatableusingthevarrayobjecttype.Notethatthereisnostoragetablerequiredforvarrays:

CREATETABLEt_annual_prod

(prod_codeVARCHAR2(8),

yearNUMBER,

productionV_GEO_PROD)

/

Atthisstage,ifweneedtomodifythevarraystructurethatis,toincreasethelimitsize,wecandosousingtheALTERTYPE…MODIFYstatement.Hereisanexamplethatincreasesthevarraylimitsizeto10:

ALTERTYPEv_geo_prodMODIFYLIMIT10INVALIDATE;

Thepreviousscriptinvalidatesalldependentobjects.TheotheroptionisCASCADE,whichcascadesthechangestothedependentobjects.TheCASCADE[NOT]INCLUDINGTABLEDATAoptioncontrolswhethertheunderlyingdataimageofvarraytypeinstancesneedstobeupdatedorjustthetablemetadata.

Ifthesizeofvarraycolumnvalueexceeds4000bytes,ithastobestoredasanLOB.For

thispurpose,youmustincludetheLOBstorageinformationinthevarraymetadata.We’llcreateavarraycolumnwithLOBstoragefordemopurposeanddropitlater:

CREATETYPEref_geo_prodASVARRAY(10)OFot_num_2;

/

ALTERTABLEt_annual_prod

ADD(gl_prodref_geo_prod)

VARRAYgl_prodSTOREASLOBprod_lob

/

ALTERTABLEt_annual_prodDROPCOLUMNgl_prod

/

OperationsonvarraytypecolumnsSimilartonestedtables,thecolumnsofvarraystoreinstancesofvarrayobjecttypes.However,fundamentaldifferencesfromnestedtablesimpactcertainoperationsinvarrays.Oneofthemajordifferencesisthatpiecewiseoperationsarenotpossiblewithvarrays.

Insertingvarraycollectiontypeinstance

ThefollowingINSERTstatementscreatetworecordsintheT_ANNUAL_PRODtable.Thevarrayinstanceusesacollectionconstructor,whiletheobjecttypeinstanceusesthedefaultobjecttypeconstructortoprovidetheinputvalues:

INSERTINTOt_annual_prod

VALUES('PROD-A',2010,v_geo_prod(ot_num_2('NAS',50),

ot_num_2('EMEA',32),

ot_num_2('APAC',47)))

/

INSERTINTOt_annual_prod

VALUES('PROD-A',2011,v_geo_prod(ot_num_2('NAS',54),

ot_num_2('APAC',57),

ot_num_2('EMEA',37)))

/

COMMIT

/

Withvarrays,piecewiseinsertsarenotpossible.Ifyouhavetoaddanewvarrayelement,youmustfollowthevarraycolumnatomicupdateprocess.

Queryingvarraycolumn

Avarraycolumncanbequeriedeitherasanobjecttypeinstanceorinarelationalformat.Let’scheckthewaystoquerydatafromT_ANNUAL_PRODtable(ignoretheoutputformattingissues):

setlines150

colproductionformata50

SELECT*FROMt_annual_prod

/

PROD_CODYEARPRODUCTION(STR,NUM)

----------------------------------------------------------------

PROD-A2010V_COUNTRY_PROD(OT_NUM_2('NAS',50),

OT_NUM_2('EMEA',32),OT_NUM_2('APAC',47))

PROD-A2011V_COUNTRY_PROD(OT_NUM_2('NAS',54),

OT_NUM_2('APAC',57),OT_NUM_2('EMEA',37))

Thepreviousresultcontainstheinstancesofvarraysaswellastheobjecttype.Thefollowingquerysimplyselecttheobjecttypeinstances:

SELECTT.prod_code,T.year,value(t1)val

FROMt_annual_prodT,TABLE(T.production)T1

/

PROD_CODYEARVAL(STR,NUM)

-------------------------------------------------------

PROD-A2010OT_NUM_2('NAS',50)

PROD-A2010OT_NUM_2('EMEA',32)

PROD-A2010OT_NUM_2('APAC',47)

PROD-A2011OT_NUM_2('NAS',54)

PROD-A2011OT_NUM_2('APAC',57)

PROD-A2011OT_NUM_2('EMEA',37)

Well,thislooksgood.Tounnestalltheobjectvaluesofaninstanceinarelationalformat,youcanusetheTABLEclause.Hereisthequery:

SELECTT.prod_code,T.year,T1.str,T1.num

FROMt_annual_prodT,TABLE(T.production)T1

/

PROD_CODYEARSTRNUM

-----------------------------------------------------

PROD-A2010NAS50

PROD-A2010EMEA32

PROD-A2010APAC47

PROD-A2011NAS54

PROD-A2011APAC57

PROD-A2011EMEA37

6rowsselected.

Iftherowsexistintheparenttablewithoutanychildinstance,youcanspecifythe(+)signasyouwoulddowithouterjoins.Forexample,thepreviousquerycanberewrittenas:

SELECTT.prod_code,T.year,T1.str,T1.num

FROMt_annual_prodT,TABLE(T.production)(+)T1

/

Updatingthevarrayinstance

Forvarrays,piecewiseinsertsandupdatesarenotpossible.Onlyatomicchangesareallowed,whichmeansthatanentirevarrayinstancehastobemodifiedtoupdateavarrayelement.

ThefollowingPL/SQLblockupdatestheproductionvaluesofEMEAintheyear2010throughaconstructor.NotetheuseofaSQLvarrayinthePL/SQLblock:


DECLARE

/*Createalocalvarrayvariableandinitializewiththenewvarray

instance*/

l_new_geoprodv_geo_prod:=v_geo_prod(ot_num_2('NAS',50),

ot_num_2('EMEA',42),ot_num_2('APAC',47));

BEGIN

/*Updatetheproductioninstancewiththelocalvarrayvariable*/

UPDATEt_annual_prod

SETproduction=l_new_geoprod

WHEREprod_code='PROD-A'

ANDyear=2010;

COMMIT;

END;

/

VarrayinPL/SQLThefollowingPL/SQLshowsthelocaldeclarationofavarrayobjectinaPL/SQLblock:

/*EnabletheSERVEROUTPUTtodisplaytheresults*/

SETSERVEROUTPUTON


DECLARE

/*Declarealocalvarraytype,definecollectionvariableandinitialize

it*/

TYPElocal_varrayISVARRAY(4)OFVARCHAR2(100);

l_objlocal_varray:=local_varray('ORCL','SAP','IBM');

BEGIN

/*Iteratethearrayobjecttoprintthevarrayelements*/

FORIIN1..l_obj.COUNT

LOOP

DBMS_OUTPUT.PUT_LINE('Varrayelements:'||l_obj(I));

ENDLOOP;

END;

/

Varrayelements:ORCL

Varrayelements:SAP

Varrayelements:IBM


ComparingthecollectiontypesThefollowingtablecomparesthecollectiontypesbasedontheconsiderations.

Comparingfactor Nestedtable Varray Associativearray

Maximumsize Unboundandgrowsdynamically. Bounded.However,varraysize,can

onlybeincreasedthereafter.Unboundandgrowsdynamically.

Sparsity Startsdensebutmaybecomesparseduetodeletions. Alwaysdense. Canbesparse.

Storageconsiderations

Out-of-linestorageinaseparatestoragetable.

In-linestorageupto4000bytes.

Forout-of-linestorage,theLOBclausemustbespecified.

Non-persistentcollectionusesprogrammemorythatisUGA.

Queryingability

Anestedtabletypecolumncanbequeriedasaninstance.However,unnestingofaninstanceispossibleusingtheTABLEorCASTclause.

Avarraytypecolumncanbequeriedasaninstance.However,unnestingofaninstanceispossibleusingtheTABLEorCASTclause.

Non-persistentcollection.

DMLoperations

Piecewiseandatomicoperationspossible. Onlyatomicoperationsarepossible.

OnlyatomicoperationsallowedwithinaPL/SQLblock.

Ordering Unorderedindex Retainstheindexorder. Retainstheindexorder.

PerformanceThejoinbetweentheparentandstoragetablemightbeadecidingfactor.OptimizeusingIOTsandlocators.

Varraysstoredin-linegivebetterperformancethannestedtablesbecausenojoinsaremadeduringdataretrieval.

Performancedependentonthesizeofassociativearraysandblockoperations.

Thecommonexceptionsthatyoumightencounterduringthecollectiondesignphaseareasfollows:

COLLECTION_IS_NULL:ThisexceptionoccurswhenthecollectionisNULLNO_DATA_FOUND:ThisexceptionoccurswhentheelementcorrespondingtoasubscriptdoesnotexistSUBSCRIPT_BEYOND_COUNT:ThisexceptionoccurswhentheindexexceedsthenumberofelementsinthecollectionSUBSCRIPT_OUTSIDE_LIMIT:ThisexceptionoccurswhentheindexisnotalegalvalueVALUE_ERROR:Thisexceptionoccurs,ifyoutrytoaccessanelementwithoutanindex

SelectingtheappropriatecollectiontypeHereareafewguidelinesthatcanhelpyoudecidetheappropriateusageofcollectiontypeinprograms:

Associativearrays:

UsewhenyouhavetotemporarilyholdtheprogramdatainahashmaplikeastructureoranarrayNotethatthereisnomethodtocompareassociativearraysCanbeusedforkey-valuedatamodelswithstringkeys

Nestedtables:

Canbeusedformodelingone-to-manyrelationshipswithintheparenttableYoucancomparecollectionsusingequalityandnon-equality,ormultisetoperatorsCanbeusedForperformingpiecewisetransactionsonthechildrows

Varray:

UsewhenyouknowthemaximumcountofelementsinthecollectionstructureExceptfornullity,youcannotperformcomparisonoperationsTheorderoftheelementshastobepreserved

Oracle12cenhancementstocollectionsOracleDatabase12callowsajoinbetweenatableandacollectiontype.IfanSQLcollectiontypeisusedasareturntypeofafunction,thetableandthefunctionoutputcanbejoinedusingCROSSAPPLYandOUTERAPPLY.Thefunctionmustuseavaluefromthejoiningtableasaparameterandreturnacollectionvariableofanestedtableorvarraytype.

Forthepurposeofillustration,letuscreatethetesttablesusingdictionaryviewsfromtheOracleDatabase.ThetableT_TBS_OBJcontainsthetablespaceinformationandT_SEGMENTScontainsthesegmentscreatedonthesetablespaces:

/*CreatetableT_TBS_OBJ*/

CREATETABLEt_tbs_obj

AS

SELECTtablespace_name,status,allocation_type

FROMuser_tablespaces

/

/*CreatetableT_SEGMENTS*/

CREATETABLEt_segments

AS

SELECTsegment_name,segment_type,tablespace_name,bytes,blocks

FROMuser_segments

/

We’llcreatethenestedtablecollectiontobeusedinthestring:

CREATETYPEnt_stringASTABLEOFVARCHAR2(128);

/

ThefunctionF_GET_SEGMENTSreturnsthesegmentscreatedonagiventablespaceasanestedtablecollectiontype:

/*Createafunctiontoreturnsegmentscreatedonatablespace*/

CREATEORREPLACEFUNCTIONf_get_segments(p_nameVARCHAR2)

RETURNnt_string

AS

l_segnt_string;

BEGIN

/*SelectquerytofetchthesegmentsfromT_SEGMENTS*/

SELECTCAST(COLLECT(segment_name)asnt_string)

INTOl_seg

FROMt_segments

WHEREtablespace_name=p_name;

RETURNl_seg;

END;

/

ThefollowingqueryusestheCROSSAPPLYmethodtojointhetableandthefunction.Notethattheoutputliststhetablespacenameandthesegmentscreatedonit.Uniquely,therearetwotablespacesthatisUSERSandORCL.Whatabouttheremainingtablespaces?Let’s

figurethatoutinthenextcodelisting:

SELECT*

FROMt_tbs_objCROSSAPPLYf_get_segments(tablespace_name)

/

TABLESPACE_NAMESTATUSALLOCATIONCOLUMN_VALUE

----------------------------------------------------------------

USERSONLINESYSTEMDEPT

USERSONLINESYSTEMEMP

USERSONLINESYSTEMSALGRADE

ORCLONLINESYSTEMT_BAT_SCORES

ORCLONLINESYSTEMT_ANNUAL_PROD

ORCLONLINESYSTEMT_OBJ

ORCLONLINESYSTEMT_TMP_DB

ORCLONLINESYSTEMT_ROW_ARCH

ORCLONLINESYSTEMT_DEF_COLS

ORCLONLINESYSTEMT_FUN_PLSQL

ORCLONLINESYSTEMNT_SCORES_ST

USERSONLINESYSTEMPK_DEPT

USERSONLINESYSTEMPK_EMP

USERSONLINESYSTEMSYS_C0010393


USERSONLINESYSTEMSYS_FK0000093178N00003$

16rowsselected.

NotethatthereareothertablespacessuchasSYSTEMandSYSAUXwithnousersegmentscreatedonthem.Byvirtueofcrossjoin,thetablespaceswithnosegmentswereeliminatedfromtheoutput.Insuchcase,wecanusetheOUTERAPPLYjoinmethod:

SELECT*

FROMt_tbs_objOUTERAPPLYf_get_segments(tablespace_name)

/

TABLESPACE_NAMESTATUSALLOCATIONCOLUMN_VALUE

---------------------------------------------------------------

SYSTEMONLINESYSTEM

SYSAUXONLINESYSTEM

UNDOTBS1ONLINESYSTEM

TEMPONLINEUNIFORM

USERSONLINESYSTEMDEPT

USERSONLINESYSTEMEMP

USERSONLINESYSTEMSALGRADE

ORCLONLINESYSTEMT_BAT_SCORES

ORCLONLINESYSTEMT_ANNUAL_PROD

ORCLONLINESYSTEMT_OBJ

ORCLONLINESYSTEMT_TMP_DB

ORCLONLINESYSTEMT_ROW_ARCH

ORCLONLINESYSTEMT_DEF_COLS

ORCLONLINESYSTEMT_FUN_PLSQL

ORCLONLINESYSTEMNT_SCORES_ST

USERSONLINESYSTEMPK_DEPT

USERSONLINESYSTEMPK_EMP



USERSONLINESYSTEMSYS_FK0000093178N00003$

DWH_DATAONLINESYSTEM

FIN_DATAONLINESYSTEM

22rowsselected.

PL/SQLcollectionmethodsOracleprovidesasetofmethodsthatcanworkwithcollectionsfordevelopmentoperations.Thedevelopmentoperationscanbedeletinganelement,trimmingthecollectiontype,orfetchingfirstandlastsubscripts.Thesyntaxforallthecollectionmethodsisasfollows:

[COLLECTION].METHOD(PARAMETERS)

EXISTSTheEXISTSfunctioncheckstheexistenceofanelementinacollection.Thegeneralsyntaxofthisfunctionis[COLLECTION].EXISTS(<index>).Itacceptsthesubscriptastheinputargumentandsearchesforitintheassociatedcollection.Iftheelementcorrespondingtotheindexexists,itreturnsTRUE,orelsereturnsFALSE.Itistheonlymethodthatdoesn’traiseanyexceptionwhenusedwithacollection.

ThefollowingPL/SQLblockdeclaresalocalnestedtablecollectionanditstwovariables.Whileonearrayisuninitialized,theotheroneisinitializedwithsampledata.Itcheckstheexistenceofthefirstelementinbotharrays:


SETSERVEROUTPUTON


DECLARE

/*Declarealocalnestedtablecollection*/

TYPEcoll_method_demo_tISTABLEOFNUMBER;

/*Declarecollectiontypevariables*/

L_ARRAY1coll_method_demo_t;

L_ARRAY2coll_method_demo_t:=coll_method_demo_t(45,87,57);

BEGIN

/*Checkifthefirstcellexistsinthearray1*/

IFL_ARRAY1.EXISTS(1)THEN

DBMS_OUTPUT.PUT_LINE('Element1foundinArray1');

ELSE

DBMS_OUTPUT.PUT_LINE('Element1NOTfoundinArray1');

ENDIF;

/*Checkifthefirstcellexistsinthearray2*/

IFL_ARRAY2.EXISTS(1)THEN

DBMS_OUTPUT.PUT_LINE('Element1foundinArray2');

ELSE

DBMS_OUTPUT.PUT_LINE('Element1NOTfoundinArray2');

ENDIF;

END;

/

Element1NOTfoundinArray1

Element1foundinArray2


COUNTTheCOUNTfunctioncountsthenumberofelementsinaninitializedcollection.Foruninitializedcollections,themethodraisestheCOLLECTION_IS_NULLexception.

NoteTheCOUNTfunctionreturnszerowhen:

Anestedtableorvarraycollectionisinitializedwithanemptycollection

Anassociativearraydoesn’thaveanyelements

Itcanbeusedwithallthreetypesofcollections.

ThefollowingPL/SQLblockdeclaresalocalnestedtablecollectionandavariableofnestedtabletype.Letuschecktheelementcountinboththecollectionvariables:


SETSERVEROUTPUTON


DECLARE

/*Declarethelocalcollectiontype*/


/*Declareandinitializethecollectionvariables*/

l_loc_varnt_local:=nt_local(10,20,30);

BEGIN

DBMS_OUTPUT.PUT_LINE('Thearraysizeis'||l_loc_var.count);

END;

/

Thearraysizeis3


LIMITTheLIMITfunctionreturnsthemaximumnumberofelementsthatcanbestoredinaVARRAYcollectiontype.ThemethodraisestheCOLLECTION_IS_NULLexceptionforuninitializedcollections.

NoteForassociativearraysornestedtables,theLIMITmethodreturnsNULL.

ThefollowingPL/SQLblockdeclaresalocalvarraytypeandavariableofitstype.Thevarraytypevariablehasbeeninitializedwithtestdata.ObservethedifferencebetweentheCOUNTandLIMITmethods:


SETSERVEROUTPUTON


DECLARE

/*Declarelocalvarrayanditsvariable*/

TYPEva_localISVARRAY(10)OFNUMBER;

l_arrayva_local:=va_local(10,20,30);

BEGIN

/*Displaythecurrentcount*/

DBMS_OUTPUT.PUT_LINE('Thevarraysizeis'||L_ARRAY.COUNT);

/*Displaythemaximumlimit*/

DBMS_OUTPUT.PUT_LINE('Thevarraymaxsizeis'||L_ARRAY.LIMIT);

END;

/

Thevarraysizeis3

Thevarraymaxsizeis10


FIRSTandLASTTheFIRSTandLASTfunctionsreturnthefirstandlastelementsofacollection.Foranemptycollection,boththemethodsreturnaNULLvalue.Thesemethodscanbeusedwithallthreetypesofcollections.TheFIRSTandLASTmethodsraisetheexceptionCOLLECTION_IS_NULLtouninitializedcollections.

ThefollowingPL/SQLblockdemonstratestheuseoftheFIRSTandLASTmethodswithaninitializedcollection:


SETSERVEROUTPUTON

/*StartthePL/SQLbock*/

DECLARE

/*Displayalocalnestedtablecollection*/

TYPEcoll_method_demo_tISTABLEOFNUMBER;

L_ARRAYcoll_method_demo_t:=coll_method_demo_t(10,20,30);

BEGIN

/*Displaythefirstandlastelements*/

DBMS_OUTPUT.PUT_LINE('Firstelement:'||L_ARRAY(L_ARRAY.FIRST));

DBMS_OUTPUT.PUT_LINE('Lastelement:'||L_ARRAY(L_ARRAY.LAST));

END;

/

Firstelement:10

Lastelement:30


PRIORandNEXTThePRIORandNEXTfunctionstakeaninputindexandreturnitspreviousandnextindex.IfthePRIORandNEXTfunctionsareusedwithfirstandlastindexesrespectively,theresultisNULL.

Boththemethodscanbeusedwithallthreetypesofcollections.ThePRIORandNEXTmethodsraiseCOLLECTION_IS_NULLexceptionwhenappliedtouninitializedcollections.ThefollowingPL/SQLshowstheusageofthePRIORandNEXTmethodswithaPL/SQLtypecollection:


SETSERVEROUTPUTON


DECLARE

/*Declarealocalnestedtablecollection*/


L_ARRAYnt_local:=nt_local(10,20,30,100,48,29,28);

l_num_idxNUMBER;

BEGIN

/*Capturetheelementbefore4thindex*/

l_num_idx:=l_array.prior(4);

DBMS_OUTPUT.PUT_LINE('Indexbefore4thelement:'||l_num_idx);

/*Deletethefifthelement*/

l_array.delete(5);

/*Capturetheelementafter4thindex*/

l_num_idx:=l_array.next(4);

DBMS_OUTPUT.PUT_LINE('Indexafter4thelement:'||l_num_idx);

END;

/

Indexbefore4thelement:3

Indexafter4thelement:6


IntheprecedingPL/SQLblock,thelocalnestedtablecollectionwasrenderedsparseafterthefifthelementwasdeleted.

EXTENDTheEXTENDfunctionisusedtoappendelementstoapersistentcollection.Itcannotbeusedwithassociativearrays.Beinganoverloadedfunction,EXTENDcanbeusedtoappendafinitenumberofelementswithadefaultvalue:

EXTEND:ItappendsthecollectionwithaNULLelement.EXTEND(x):ItappendsthecollectionwithanxnumberofNULLelements.EXTEND(x,y):Itappendsthecollectionwithxelementswithvaluesasthatoftheyelement.Iftheyelementdoesn’texist,thesystemraisesaSUBSCRIPT_BEYOND_COUNTexception.

ThefollowingPL/SQLblockdemonstratestheextensionofacollectiontypeusingallthreesignaturesoftheEXTENDmethod.ThefirstextensionappendsthefourthNULLelementtothearray.ThesecondextensionappendsthefifthandsixthNULLelementstothearray.Thethirdextensionappendstheseventhandeighthelementsas10(thevalueofthefirstelement)tothearray:


SETSERVEROUTPUTON


DECLARE

/*Declarelocalnestedtablecollectiontype*/


/*Declarecollectiontypevariableandinitializeit*/

L_ARRAYnt_local:=nt_local(10,20,30);

l_num_idxNUMBER;

BEGIN

/*Extendthecollectionusingdefaultsignature*/

l_array.extend;

l_num_idx:=l_array(l_array.last);

DBMS_OUTPUT.PUT_LINE(L_ARRAY.LAST||'elementis='||l_num_idx);

/*ExtendthecollectionbyaddingtwoNULLelements*/

l_array.extend(2);



/*Extendthecollectionbyaddingtwoelementswithavalue*/

l_array.extend(2,1);



END;

/

4elementis=

6elementis=

8elementis=10


TheEXTENDmethodraisestheCOLLECTION_IS_NULLexceptionforuninitializedcollections.Ifavarrayisattemptedforextensionbeyonditsmaximumallowedlimit,OracleraisesanSUBSCRIPT_BEYOND_LIMITexception.

TRIMTheTRIMfunctionisusedtocuttheelementsfromapersistentcollection.Itcannotbeusedwithassociativearraytypecollections.TRIMisanoverloadedmethod,whichcanbeusedinthefollowingtwosignatures:

TRIM:Ittrimsoneelementfromtheendofthecollection.TRIM(n):Ittrimsnelementsfromtheendofthecollection.Ifnexceedsthetotalcountofelementsinthecollection,thesystemraisesaSUBSCRIPT_BEYOND_COUNTexception.NoactionisdefinedforNULLvalueofn.

ThefollowingPL/SQLblockshowstheoperationoftheTRIMmethodonaninitializedPL/SQLtablecollectiontype:


SETSERVEROUTPUTON


DECLARE

/*Declarealocalnestedtablecollectiontype*/


/*Declareacollectionvariableandinitializeit*/

l_arraynt_local:=nt_local(10,20,30,40,50);

l_num_idxNUMBER;

BEGIN

/*Trimthelastelementofthecollection*/

l_array.trim;



/*Trimthelast2elementsofthecollection*/

DBMS_OUTPUT.PUT_LINE('Trimmingthearray…');

l_array.trim(2);



END;

/

4elementis=40

Trimmingthearray…

2elementis=20


TheTRIMmethodraisesaCOLLECTION_IS_NULLexceptionforuninitializedcollections.

DELETETheDELETEfunctionisusedtodeleteelementsfromagivencollection.TheDELETEoperationleavesthecollectionsparse.AnyreferencetothedeletedindexwouldraiseaNO_DATA_FOUNDexception.TheDELETEmethodraisesaCOLLECTION_IS_NULLexceptionforuninitializedcollections.Itcanbeusedwithallthreetypesofcollections.

Theoverloadedmethodcanbeusedinthefollowingsignatures:

DELETE:ItflushesoutalltheelementsofacollectionDELETE(n):ItdeletesthenthindexfromthecollectionDELETE(n,m):Itperformsrangedeletion,wherealltheelementswithintherangeofthesubscriptsnandmaredeleted

ThefollowingPL/SQLblockdeclaresacollectionalongwithitscollectionvariable.Thisprogramdisplaysthefirstelementofthecollectionbeforeandafterthedeletionofthefirstsubscript:


SETSERVEROUTPUTON


DECLARE

/*Declarethelocalnestedtablecollection*/


/*Declareandinitializeacollectionvariable*/

l_arraynt_local:=nt_local(10,20,30,40,50);

l_num_idxNUMBER;

BEGIN

/*Capturetheelementatthefirstplace*/

l_num_idx:=l_array(l_array.first);

DBMS_OUTPUT.PUT_LINE('1stelementis'||l_num_idx);

/*Deletethe1stelementfromthecollection*/

L_ARRAY.DELETE(1);

/*Capturetheelementatthefirstplace*/

l_num_idx:=l_array(l_array.first);

DBMS_OUTPUT.PUT_LINE('1stelementis'||l_num_idx);

END;

/

1stelementis10

1stelementis20


Oracledoesn’tallowthedeletionofindividualelementsinavarraycollection.Eitheralltheelementsofavarrayareremovedusingthe[VARRAY].DELETEmethodortheelements

canbetrimmedfromtheendofthevarraycollection:


SETSERVEROUTPUTON


DECLARE

/*Declarethelocalvarraycollection*/

TYPEva_arrayISVARRAY(10)OFNUMBER;

/*Declareacollectionvariableandinitializeit*/

L_ARRAYva_array:=va_array(10,20,30,40,50);

BEGIN

/*Deletethesecondelementofvarray*/

L_ARRAY.DELETE(2);

END;

/

L_ARRAY.DELETE(2);

*

ERRORatline8:


PLS-00306:wrongnumberortypesofargumentsincallto'DELETE'


PL/SQL:Statementignored.

TipItisrecommendedthattheTRIMandDELETEmethodsmustnotbeoperatedtogetherorsimultaneouslyonacollection.TheDELETEmethodretainsaplaceholderforthedeletedelementwhiletheTRIMmethoddestroystheelementfromthecollection.Therefore,theoperationsequenceDELETE(last)followedbyTRIM(1)wouldresultintheremovalofasingleelementonly.

SummaryThischaptercoversoneofthemoreinterestingfeaturesofPL/SQLprogramming—collections.WediscussedandlearnedthethreetypesofcollectionsinPL/SQLthatisassociativearrays,nestedtablesandvarrays.Readersshouldunderstandtheapplicationofthesecollectiontypesindifferentsituations.Thecomparativestudyofallthreewouldhelpreaderstodifferentiatebetweeneachoneandchoosethemostappropriateoneintheirdevelopment.

ThenextchapterwillexploreanotherdistinctivecapacityofPL/SQLasalanguage,thatisintheuseofexternalprocedures.

PracticeexerciseWhichtwostatementsaretrueaboutassociativearrays?

1. Associativearrayscanhavenegativesubscripts.2. Associativearraysarealwaysdensecollections.3. Associativearraysdon’tneedinitializationinaPL/SQLblock.4. Theupperlimitofassociativearrayscanbydynamicallymodified.

Whichofthefollowingstatementsistrueaboutnestedtables?

1. Nestedtablesarestoredinasegmentdifferentfromthatofaparenttable.2. Nestedtablecolumnscanhavestringsubscripts.3. Nestedtablescangrowdynamicallyuptoanyextent.4. Adatabasecolumnofnestedtablecollectiontypecanbeseparatelyqueriedby

itsstoragename.

Onlyvarrayscanhavesequentialnumbersassubscripts.

1. True2. False

Whichofthefollowingassociativearraydeclarationsis/arecorrect:

DECLARE

TYPET1ISTABLEOFNUMBERINDEXBYBOOLEAN;

TYPET2ISTABLEOFVARCHAR2(10)INDEXBYNUMBER;

TYPET3ISTABLEOFDATEINDEXBYSIGNTYPE;

TYPET4ISTABLEOFEMPLOYEES%ROWTYPEINDEXBYPOSITIVE;

BEGIN

…

…

END;

1. T12. T23. T34. T4

Whichofthefollowingstatementsis/aretrueaboutvarrays?

1. ThelimitofvarrayelementscanbemodifiedduringruntimeusingtheALTERTABLEstatement.

2. AvarrayelementcanbedeletedusingtheDELETEmethod.3. Foranemptycollectionofvarraytype,thevalueofLASTisequaltoCOUNT.4. Varrayscanexistassparsecollections.

WhatwillbetheoutputofthefollowingPL/SQLblock:

DECLARE

TYPETISTABLEOFNUMBER;

L_NUMT:=T(1,2);

BEGIN

DBMS_OUTPUT.PUT_LINE(L_NUM(1));

L_NUM:=T(10,20);

DBMS_OUTPUT.PUT_LINE(L_NUM(1));

END;

1. 1and1.2. 1and10.3. OracleraisesaCOLLECTION_IS_NULLexceptionatline5.4. 10and10.

TheEMPLOYEEStablestoresthedetailsof14employees.IdentifythesolutionoftheerrorinthefollowingPL/SQLprogram:

DECLARE

TYPEEMP_VARRAY_TISVARRAY(10)OFEMPLOYEES%ROWTYPE;

L_EMPEMP_VARRAY_T:=EMP_VARRAY_T();

BEGIN

DBMS_OUTPUT.PUT_LINE(L_EMP.COUNT);

SELECT*

BULKCOLLECTINTOL_EMP

FROMEMPLOYEES;

DBMS_OUTPUT.PUT_LINE(L_EMP.COUNT);

END;

/

0

DECLARE

*

ERRORatline1:

ORA-22165:givenindex[11]mustbeintherangeof[1]to[10]

ORA-06512:atline6

1. Thevarraysizemustbeincreasedto14orahigherlimit.2. Thevarrayvariablemustbeinitialized.3. Dataforonly10employeesmustbeselectedintoavarrayvariable.4. TheVarraydefinitioniswrong;arecordtypecannotbeusedasanelement

typeofavarraycollection.

Whichofthefollowingstatementsarewrongaboutthecollectionmethods?

1. EXISTSraisesaNO_DATA_FOUNDexceptioniftheelementfortheinputsubscriptdoesnotexist.

2. DELETEcanbeusedwithvarrays.3. LIMITreturnsthecurrentlimitofnestedtablecollections.4. TRIMremovesanelementofthecollectionfromtheend.

Chapter5.UsingAdvancedInterfaceMethodsOracleenablestheapplicationdeveloperstocreatePL/SQLroutinesthatcaninvokeprogramswritteninnon-Oracleprogramminglanguages.AnexternalprogramcanbeaC,C++based,orJava-basedprogram.ExternalprocedureswereintroducedinOracle8itoaddextensibilitytotheOracleDatabaseenginebyallowingthenon-Oracleprogramstoexecuteinthedatabasekernel.Thischaptercoverstheexternalproceduresandtheirimplementationinthefollowingtopics:

UnderstandingexternalroutinesArchitectureandbenefitsExecutingexternalCprogramsfromPL/SQLExecutingexternalJavaprogramsfromPL/SQL

OverviewofExternalProceduresOracleprovidesarichplatformforapplicationprogrammingthroughPL/SQLandthesupportformultilanguageprograms.Programminglanguagesthatallowthetechnicaltranslationofrealworldproblemshavedifferentfeaturesandadvantages,forexample,PL/SQListightlyintegratedwithSQLandcomputation-basedlogiccanberunefficientlyinC.Someofthecrucialfactorsthatdeterminethechoiceofaprogramminglanguagecanbecodeperformance,portability,andsecurity.Therefore,youmightseeapplicationdevelopmentinvolvingmultipleprogramminglanguages.

OraclePL/SQLallowsuserstocreateaPL/SQLprogramthatcallsaCorJavaprocedure.Thespecialpurposeinterfaceallowstheuserstoutilizethestrengthsandfeaturesofmultipleprogramminglanguagesandsupportcodereusability.

ExternalProceduresAnexternalprocedureisstoredinadynamiclinkedlibrary(DLL)orasimilarunit,whichisprototypedinacallspecificationusingOraclePL/SQL.WheneveraPL/SQLprocedureiscalled,thelanguagecompilerloadsthetargetlibraryatruntimeandexecutestheexternalprogramasaPL/SQLprocedure,entirelyandnativelywithintheOracleDatabase.Aninterestingcapabilityofanexternalprocedureisthatthecallspecificationisindependentofthecodechangestotheprogram.

Theprecedingdiagramshowsahigh-leveloverviewofthecomponentsinvolvedinanexternalprocedurecall.Wewilldiscussthemindetailinthischapter.

ExternalproceduresenhancethedevelopmentplatformoftheOracleDatabases.AC-basedorJava-basedprogram,whenexecutedfromthedatabaseserver,avoidsthenetworkroundtripsmadeforclient-to-databasecommunication.

ComponentsofexternalprocedureexecutionflowInthissection,wewilllearnaboutthedatabasecomponentsinvolvedintheexecutionofanexternalprocedure.

TheextprocagentTheextprocagentplaysthemostvitalroleininterfacingexternalproceduresintheOracleDatabase.ItisaprocessstartedbytheOracleDatabaseordatabaselistener,whichfacilitatestheexecutionofanexternalprocedurewheneverrequired.Itcarriesrelevantinformationsuchasthelibrarypath,procedurename,andarguments.Itreturnstheresultoftheexecutionbacktothedatabaseprocessingengine.

Inadedicatedservermode,eachsessionwillhaveanewinstanceoftheextprocprocess.Inamultiuserapplication,multiplesessionswithmultipleextprocprocessesmayresultinadisproportionateallocationofmemoryresources.Inasharedservermode,amultithreadedextprocagentcanprovidetheefficientutilizationofserverresourcesbymaintainingasharedpooloftheextprocprocesses.

TheLibraryobjectAnexternalprocedurecanbeexecutedasasharedlibraryinOracle.Alibraryisanoperatingsystemfile,whichcanbedynamicallyloadeduponrequest.OnaWindowsmachine,youmightbeawareofthelibraryfileswitha.dllextension,whileonUnixanditsflavors,thelibraryisstoredwitha.soextension.Alibrarycanbesharedbymultipleexternalprocedures.TheexternalprocedurecanbewritteninC,C++,Fortran,COBOL,orVisualBasic.Asharedlibrarycanbesharedacrossmultipledatabasesessions,thusoptimizingthememoryconsumption.

Fortherepresentationofthesharedlibraryacrossaschema,aschemaobjectiscreatedasanaliaslibrary.Thislibrarycanbecreatedusingthefollowingsyntax:

CREATELIBRARY[schema].library_name

{IS|AS}'library_path'

[AGENT'agent_link'];

AlibrarycanbecreatedbySYSorauserwiththeCREATELIBRARYprivilege.AuserwiththeEXECUTEprivilegeonthelibrarycanreferitinthecallspecifications.Thelibrarypathmustbeaccessiblebytheextprocprocess,thatis,eitheritmustbeexplicitlyspecifiedinEXTPROC_DLLSorthelibrarymustresideinthe$ORACLE_HOME/bin/or$ORACLE_HOME/lib/folders.

NoteEXTPROC_DLLSisanenvironmentparametersetinextproc.ora,(discussedlaterinthischapter).

CalloutandCallbackTherearetworelevantterms—calloutandcallback—associatedwiththehandlingofanexternalprogram.

WhenthePL/SQLprocedureinvokesanexternalprocedure,thecallisreferredtoasacallout.IftheexternalprocedureinvokesanSQLstatement,whichdrivesthedatabaseengine,thecallisreferredtoasacallback.

CallSpecificationAcallspecificationisrequiredtopublishanexternalprocedure.Itenablestheregistrationofanexternalprocedure,databaselibrary,parametermapping,memorymanagement,andexternalprocedureexecution.ItconsistsofasetofstatementsembeddedinaPL/SQLsubprogram.ItcanbespecifiedinstandalonePL/SQLsubprograms,PL/SQLpackagespecificationsorbody,andabstractdatatypes.

Thesyntaxforacallspecificationisasfollows:

ASLANGUAGE[C|JAVAmethodsignature]

[LIBRARY(libraryname)]

[NAME(externalprogramname)]

[WITHCONTEXT]

[AGENTIN(formalparameters)]

[PARAMETERS(parameterlist)]

TheASLANGUAGEclausespecifiesthepublicationofCandJavaprograms.TheASEXTERNALclauseisusedtosupporttheexternalprogramswithlegacyapplications.ForJavaprograms,youneedtospecifythecompletesignature.

TheLIBRARYisavalidschemaobject.Itisamandatoryclause.YoumusthavetheEXECUTEprivilegeonthelibrary.

TheNAMEistheexternalprocedurenamethathastobeexecutedinthelibrary.ItisamandatoryinputonlyifthecallingPL/SQLsubprogramisnameddifferentlyfromtheexternalprocedure.

ThePARAMETERSclausespecifiestheparameteralongwiththedatatype,therespectiveposition,andthepassbymethod(passbyvalueorreference).Theremightbesomechallengesinprovidingtheparameterlistbecauseofthedisparatedatatypesavailableacrosstheprogramminglanguages,supportfornullability,andprecision.

HowanExternalProcedureexecutesWheneverthePL/SQLruntimeengineencountersanexternalprocedurecall,theOracleDatabasestartstheextprocprocess.Thedatabasepassesontheinformationreceivedfromthecallspecificationtotheextprocprocess,whichhelpsittolocatetheexternalprocedurewithinthelibraryandexecuteitusingthesuppliedparameters.Theextprocprocessloadsthedynamiclinkedlibrary,executestheexternalprocedure,andreturnstheresultbacktothedatabase.

NoteTheextprocprocessrunsseparatelyfromthemaindatabasekernelprocesses.Evenifitcrashes,itwouldn’timpacttheOracledatabaseinstance.

Ifanyoftheprecedingstepsfailtoexecute,anexceptionisraised.Thefollowingisalistofcommonlyencounteredexceptions:

ORA-28576:LostRPCconnectiontoexternalprocedureagent:ThisexceptionisraisedwhentheOraclelistenerisnotabletoestablishtheconnectionwiththeextprocprocess.ORA-28595:Extprocagent:InvalidDLLpath:ThisexceptionisraisedwhentheextprocprocessisnotabletolocatetheDLLinthespecifiedlocation.Youneedtoensurethatthelibrarypathisaccessiblebytheprocess.ORA-06521:PL/SQLErrormappingfunction:Thisexceptionisraisedwhentheexternalprogramiswronglyprototypedinthecallspecification.Thereasonscouldbeaparameterdatatypemismatchorthewrongprogramname.

EnvironmentsetupTheextprocprocessattemptstolocatethelibraryfilesinanaccessiblelocation.Thelocationofthetargetlibrariescaneitherbespecifiedwiththelistenerorinanextproc.orafile.Bydefault,theextprocprocesswillbestartedbytheOracleDatabase.Ifyouwanttocontinuewiththedefaultbehavior,itisrecommendedtospecifythelibrarypathsinextproc.ora.

Ifyouareworkingwithdistributeddatabasesoramultithreadedextprocagent,youcanoverridethedefaultbehaviorbymodifyinglistener.orafile.

TNSNAMES.oraTheTNSNAMES.orafilethatgetsconfiguredatthetimeofthedatabasesoftwareinstallation(orcanbeconfiguredlater),includesanentryfortheORACLR_CONNECTION_DATAservicetosupportexternalservices.ThisserviceverifiesthenetworkconnectionbyusingtheADDRESSparametervalueandconnectsusingtheCONNECT_DATAparametervalue.Thefollowingistheentryintnsnames.orafile:

ORACLR_CONNECTION_DATA=

(DESCRIPTION=

(ADDRESS_LIST=

(ADDRESS=(PROTOCOL=IPC)(KEY=EXTPROC1521))

)

(CONNECT_DATA=

(SID=CLRExtproc)

(PRESENTATION=RO)

)

)

TheADDRESSparametervaluechecksforthelistener,whichcanreceiveIPC(InternetProcedureCalls)requeststhroughtheKEYvalue,EXTPROC1521.ThePROTOCOLparameterhasafixedIPCvaluetoestablishtheinteractionbetweentheserverandexternalservicerequests.OncetheADDRESSsetupmatchesthecurrentactivelistener,itusestheCONNECT_DATAparametervaluetospawntheextprocprocess.ThePRESENTATIONparameterisaperformanceoptimizingparameterthatdirectsthedatabaseservertoconcentrateandrespondtotheclientthroughaprotocol—Remote-Ops(RO).

TipCLRExtprocisalistenermodethatallowsaPL/SQLprogramstoaccessexternalprograms.

EXTPROC.oraInthedefaultconfiguration,youwillneedtosettheEXTPROC_DLLSenvironmentvariableinextproc.orafortheextprocprocess.Thesyntaxtobeusedisasfollows:

SETEXTPROC_DLLS=<librarypath>

ThepossiblevaluesfortheenvironmentvariableareONLY,ANY,oracolon(:),separatedbytheactualDLLpath.

NULL(default):Theextprocprocesscanonlyloadthelibrarieslocatedinthe$ORACLE_HOME/binand$ORACLE_HOME/libpaths.ONLY:[DLL:DLL…]:Thisprovidesmaximumprotectionbylimitingthenumberoflibrariesonthesystem.Theextprocprocessloadseitheroftheselibraries.[DLL:DLL…]:ThisallowsyoutospecifytheDLLpathsseparatedbyacolon.Theextprocprocesscanloadthelibrarieslocatedinthesepathsorfromthe$ORACLE_HOME/binand$ORACLE_HOME/libfolders.ANY:ThisallowsanyDLLontheservertobeloadedbytheextprocprocess.

TipUseasemicolonasadelimiterwhilespecifyinglibrariesonaWindowsserver.

Inadistributeddatabasesystem,youneedtousethemultithreadedextprocprocesstobespawnedbytheOraclelistenerandnotthedatabase.TheadvantageofhavingthemultithreadedextprocagentinanOracleDatabasesharedserverarchitectureisoptimizedresourceconsumption.Itusesasharedpoolofextprocagentthreadswhicharesequentiallyassignedinandatabasesessionsinaqueue.Themultithreadedextprocagentensurestheefficientutilizationofthesystemresources.

NoteWhenrunninganOracledatabaseserverinsharedmode,theagentprocessandlistenermustresideonthesamephysicalserver.

ExecutingexternalCprogramsfromPL/SQLLet’suswalkthroughanillustrationonhowtoexecuteanexternalprocedure,writtenintheClanguage,intheOracleDatabase.

Step1:CreatingandcompilingtheCprogram.

ThefollowingCprogram(GetMax.c)findsthemaximumofthetwonumbervalues:

#include<stdio.h>

/*Definethefunctionreturningthemaxbetweentwonumbers*/

intGetMax(intnum1,intnum2)

{

/*localvariabledeclaration*/

intresult;

if(num1>num2)

result=num1;

else

result=num2;

returnresult;

}

CompiletheprogrambyusingaCcompiler.

sh-4.3#gcc-cGetMax.c

Step2:GeneratingtheDLLandcreatingthelibraryobjectintheOracleDatabase.

WewillnowgeneratetheDLLfortheCprogram:

sh-4.3#gcc-sharedGetMax.c-oGetMax.dll

Thelibrarylocation

Thedefaultpathssearchedbytheextprocprocessforloadingtherequiredlibraryare$ORACLE_HOME/binand$ORACLE_HOME/lib.Fortestingpurposes,wewillcontinuewiththedefaults.Forthisreason,thesettinginextproc.oraremainsunchanged(toNULL),asfollows:

SETEXTPROC_DLLS=

Wewillplacethesharedlibrarygeneratedbythecompilerinthe$ORACLE_HOME/libfolder.Ifyouwanttouseanon-defaultpath,settheEXTPROC_DLLSenvironmentvariableintheextproc.ora($ORACLE_HOME/hs/)file.

ThefollowingscriptcreatesthelibraryobjectintheSCOTTschema.NotethattheSYShasgrantedtheSCOTTusertheCREATELIBRARYprivilege:

/*ConnectasSYSDBA*/

CONNsys/oracleASSYSDBA

/*GranttheCREATELIBRARYprivilege*/

GRANTCREATELIBRARYTOSCOTT

/

Grantsucceeded.

Now,theSCOTTusercancreatealibraryinthedatabaseforthesharedlibrarypath.

/*ConnectasSCOTTuser*/

CONNscott/tiger

/*Createthealiaslibraryobjectusingthe.soDLLpath*/

CREATEORREPLACELIBRARYGetMaxDll

AS'/u01/app/oracle/product/12.1.0.2/db_1/lib/GetMax.so'

/

Librarycreated.

ThelibrarymetadatacanbequeriedfromtheUSER_LIBRARIESdictionaryview.Thisviewcapturesthedataforthelibrariesownedbythecurrentuser:

SELECTlibrary_name,

file_spec,

dynamic,

status

FROMuser_libraries

/

LIBRARY_NAFILE_SPECDSTATUS

--------------------------------------------------

GETMAXDLL/u01/app/oracle/product/12.1.0.2YVALID

/db_1/lib/GetMax.so

Step3:CreatingthePL/SQLwrapperfunctionwithacallspecification.

FortheGetMaxexternalprogram,let’screateacallspecification.Withinthecallspecification,wewillprovidethelibraryname,Cprogramname,andparameters:

/*Createthefunctionwithcallspecification*/

CREATEORREPLACEFUNCTIONf_get_max

(p_num1PLS_INTEGER,p_num2PLS_INTEGER)

RETURNPLS_INTEGER

/*CallSpecificationstarts*/

ASLANGUAGEC

/*SpecifythePL/SQLlibraryobjectname*/

LIBRARYGetMaxDll

/*Specifytheexternalfunctionname*/

NAME"GetMax"

/*Specifytheparameters*/

PARAMETERS(p_num1,p_num2);

/

Functioncreated.

Step4:TestingthePL/SQLprocedure.

ThefollowinganonymousPL/SQLblockinvokestheF_GET_MAXfunction:

/*EnabletheSERVEROUTPUTtodisplaytheblockoutput*/

SETSERVEROUTPUTON

DECLARE

/*Declarelocalvariables*/

aPLS_INTEGER:=10;

bPLS_INTEGER:=30;

cPLS_INTEGER;

BEGIN

/*CalltheF_GET_MAXfunction*/

c:=F_GET_MAX(a,b);

/*Displaytheoutput*/

DBMS_OUTPUT.PUT_LINE('Themaximumnumberis-'||c);

END;

/

Themaximumnumberis-30


That’sthecorrectresult.WehavejustexecutedaCprogramfromOraclePL/SQL.AssoonasthePL/SQLblockexecutionstarts,youcantracetheextprocprocessbylistingtheprocesses.Theextprocprocessisactiveuntiltheendofthesession.

[oracle@devhost~]$ps-ef|grepextproc

oracle52641015:01?00:00:00

/u01/app/oracle/product/12.1.0.2/db_1/bin/extproc(DESCRIPTION=(LOCAL=YES)

(ADDRESS=(PROTOCOL=BEQ)))

oracle52665115015:01dev/100:00:00grepextproc

TherestrictionsonCexternalproceduresarelistedasfollows:

ThefeatureislimitedtotheplatformsthatsupportdynamicallylinkedlibrariesTheextprocprocessandPL/SQLprocedureneedtobeonthesamehostThelibraryclausecannotpointtoaremotelocationthroughadatabaselinkThemaximumnumberofparameterstoanexternalprocedureis128Parametersofcursorvariabletypesarenotsupportedwithexternalprocedures

SecuringExternalProcedureswithOracleDatabase12cTheOracleDatabasecreatestheextprocprocessandrunsundertheoperatingsystemuser,thatstartsthelistenerorrunsanOracleserverprocess.Quiteoften,youwillseetheextprocprocessrunningastheoracleuser.TheextprocprocessisnotphysicallyassociatedwiththeOracleDatabase.

OracleDatabase12cenablesenhancedsecurityforextprocbyauthenticatingitagainstauser-suppliedcredential.ThisnewfeatureallowsthecreationofausercredentialandassociatesitwiththePL/SQLlibraryobject.Whenevertheapplicationcallsanexternalprocedure,theextprocprocessauthenticatestheconnectionbeforeloadingthesharedlibrary.

TheDBMS_CREDENTIALpackageallowstheconfigurationofthecredentialthroughmembersubprograms.TheCREATELIBRARYstatementhasbeenenhancedforcredentialspecification.Anewenvironmentvariable,ENFORCE_CREDENTIAL,canbespecifiedinextproc.oratocontroltheauthenticationbytheextprocprocess.ThedefaultvalueoftheparameterisFALSE.Anothernewenvironmentvariable,GLOBAL_EXTPROC_CREDENTIAL,servesasthedefaultcredentialandisonlyusedwhenthecredentialisnotspecifiedforalibrary.IfENFORCE_CREDENTIALisFALSEandnocredentialhasbeendefinedinthePL/SQLlibrary,therewillbenouserauthentication;thismeanstheextprocprocesswillauthenticatebyusingtheprivilegesoftheuserrunningtheOracleserver.

ThefollowingPL/SQLblockcreatesacredentialbyusingDBMS_CREDENTIAL.CREATE_CREDENTIAL.ThiscredentialisbuiltusingtheORADEVuser:

BEGIN

DBMS_CREDENTIAL.CREATE_CREDENTIAL(

credential_name=>'devhost_auth',

user_name=>'oradev',

password=>'oradev')

END;

/

ThelibrarydefinitionwillincludeanadditionalCREDENTIALclause:

CREATEORREPLACELIBRARYmyextlib

AS'HelloWorld.so'

CREDENTIALdevhost_auth

/

Whentheextprocprocessreadsthecallspecificationandfindsthesharedlibrarywithasecuredcredential,itauthenticatesthelibraryonbehalfofthecredentialandthenloadsit.

ExecutingJavaprogramsfromPL/SQLLiketheCprograms,JavaprogramscanalsonativelyexecuteintheOracleDatabase.However,unlikeCexternalprograms,theJavaclassesandJavasourcefilesarestoredasschemaobjectsinthedatabase.

ExternalJavaprogramsarenotexecutedthroughOS-basedsharedlibrariesbutuseaJavasharedlibraryorlibunitforexecution.Libunitsaresimilartodynamicallylinkedlibrariesbuttheyaremappedone-to-onetotheJavaclassandarenotsharableacrosstheothermethods.

ThelibunitisloadedandexecutedbytheJavaVirtualMachine(JVM)whichresidesnativelyintheOracleDatabase.TheJVMusestheJavapoolcomponentofthesharedglobalareatoexecutetheJava-basedexternalprogram.

LoadingaJavaclassintoadatabaseAJavaprogramcanbeloadedintoanOracleDatabasebyusingtheCREATEJAVAstatementortheLOADJAVAutility.

TheCREATEJAVAstatementenablestheJavaVirtualMachinelibrarymanagertoloadaJavaclassintotheOracleDatabaseandgeneratetheRDBMSsharedlibraryorlibunitinthetargetdirectory.TheCREATEJAVAstatementsyntaxisasfollows:

CREATEJAVACLASSUSINGBFILE(directory,javaclass)

JavaclassescanalsobeloadedbyusingtheLOADJAVAutility.ThecommandlineutilityuploadstheJavaclassasalargeobjectinasystem-generatedtableandgeneratesthesharedlibrary.

Theloadjavautilitycanbeusedasperthefollowingsyntax:

loadjava{-user|-u}username/password[@database][option…]

filename[filename]...

TipYoucanuseloadjava-h|-helptogetahelperindex.

StepstoexecuteaJavaclassfromanOraclePL/SQLunitInthissection,wewillillustratetheloadingofaJavaclassintoanOracleDatabaseandinvokeitbyusingaPL/SQLprocedure.

Step1:CreatingaJavaclass.

TheComputeJavaclassincludesthefollowingtwomethodstoaddandmultiplytwonumbers:

publicclassCompute{

publicstaticintSum(intx,inty){

returnx+y;

}

publicstaticintCross(intx,inty){

returnx*y;

}

}

Step2:LoadingtheJavaclassintoOracle.

WewillnowuploadtheJavaclassintotheOracleDatabasebyusingtheloadjavautility:

[oracle@devhost~]$loadjava-userscott/tigerCompute.java

Asuccessfuluploadoperationgetsterminatedwithoutanyconfirmationmessage.YoucanconfirmtheloadoperationbyqueryingtheJavaclassintheUSER_JAVA_CLASSES,USER_OBJECTSandUSER_SOURCEdictionaryviews:

/*QuerytheUSER_JAVA_CLASSESview*/

SELECTname,kind,accessibility,source

FROMuser_java_classes

/

NAMEKINDACCESSIBILITYSOURCE

---------------------------------------

ComputeCLASSPUBLICCompute

/*QuerytheUSER_OBJECTSview*/

COLobject_nameformata30

SELECTobject_name,object_type,status

FROMUSER_OBJECTS

WHERETRUNC(created)=TRUNC(SYSDATE)

ORDERBYtimestamp

/

OBJECT_NAMEOBJECT_TYPESTATUS

---------------------------------------------------------

SYS_LOB0000093463C00002$$LOBVALID

SYS_IL0000093463C00002$$INDEXVALID

SYS_C0010407INDEXVALID

CREATE$JAVA$LOB$TABLETABLEVALID

JAVA$OPTIONSTABLEVALID

ComputeJAVASOURCEINVALID

ComputeJAVACLASSINVALID

7rowsselected.

YoucanignoretheinvalidstatusoftheJAVASOURCEandJAVACLASSobjects.Theybothwillgetvalidateduponinvocation.

TheJAVA$OPTIONStablestoresthecompileroptions:

SELECT*

FROMJAVA$OPTIONS

/

WHATOPTVALUE

-------------------------------------------------------

ComputeencodingUTF-8

Thesystem-generatedCREATE$JAVA$LOB$TABLEtablestorestheJavaclassasaSecureFilelargeobject.

NoteStartingwithOracleDatabase12c,SecureFileisthedefaultstoragemechanismforlargeobjects.

Let’sdrilldownbyasteptofurthercheckoutthetablestructurefromtheUSER_TAB_COLSdictionaryview:

SELECTtable_name,

column_name,

data_type

FROMuser_tab_cols

WHEREtable_name='CREATE$JAVA$LOB$TABLE'

/

TABLE_NAMECOLUMN_NAMEDATA_TYPE

-----------------------------------------------------

CREATE$JAVA$LOB$TABLELOADTIMEDATE

CREATE$JAVA$LOB$TABLELOBBLOB

CREATE$JAVA$LOB$TABLENAMEVARCHAR2

VerifytheLOBstorageasaSecureFilefortheLOBcolumninthetable:

SELECTtable_name,column_name,securefile

FROMuser_lobs

WHEREtable_name='CREATE$JAVA$LOB$TABLE'

/

TABLE_NAMECOLUMN_NAMESEC

----------------------------------------------

CREATE$JAVA$LOB$TABLELOBYES

Step3:PublishingtheJavaclassmethodbyusingacallspecification.

Let’screateaPL/SQLwrapperthatwillincludeacallspecificationtoregistertheJavaprogramandspecifytheparametermapping.Notethat,unlikeCprogrampublishing,youdon’tneedtospecifythelibraryunitandexternalprocedurename.TheASLANGUAGEprovidestheinterfacebetweentheJavaclassandOraclePL/SQL.

Thesyntaxforthecallspecificationisasfollows:

{IS|AS}LANGUAGEJAVA

NAME'method_fullname(parameters)

[returnjava_type_fullname]';

WeshallnowcreatethecallspecificationfortheComputeJavaclass.ThestandalonefunctionacceptstwonumbersandreturnstheirsumusingtheSummethod:

/*FunctiontopublishJavaclassmethod*/

CREATEORREPLACEFUNCTIONF_COMPUTE_SUM

(P_XNUMBER,P_YNUMBER)

RETURNNUMBER

AS

/*Specifytheexternalprogramsbaselanguage*/

LANGUAGEJAVA

NAME'Compute.Sum(int,int)returnint';

/

Functioncreated.

Step4:VerifyingtheJavaclassexecutionmethod.

Let’sinvoketheF_COMPUTE_SUMfunctiontoverifytheexecutionoftheJavaclassmethod:

variablexnumber;

variableynumber;

exec:x:=100;


exec:y:=95;


variableresultnumber;

exec:result:=f_compute_sum(:x,:y);


printresult

RESULT

----------

195

SummaryExternalproceduresdemonstratetheextensibilityfeatureofanOracleDatabasethatallowsaprogramdevelopedinnon-Oraclescriptinglanguagetobeexecutednativelyinthedatabasekernel.Thereaderswillfinditinterestingtoexplorehowtheycanenablecomplexalgorithmstorunontheserverside.

Inthenextchapter,wewillbediscussingadatasecurityfeaturecalledVirtualPrivateDatabase.Fromadataaccessstandpoint,thisfeatureisquiteimportantandeasytoimplementwithbiggerbenefits.

PracticeexerciseWhichofthefollowingstatementsaretrueabouttheextprocprocess?

1. ItloadsthesharedlibraryoftheexternalCprogram.2. ItisstartedbythePL/SQLruntimeengine.3. Itisasession-specificprocess.4. TheextprocprocesscompilestheCprogramwhileloading.

Oracle7introducedtheexternalprocedurefeatureforsendinge-mailsfromPL/SQL.

1. True2. False

DeterminetheeffectofdroppingthelibraryobjectthathasbeenusedinaPL/SQLcallspecificationwhileitisstillinuse:

1. ThePL/SQLwrappermethodgetsinvalidated.2. Thesharedlibrarygetscorrupted.3. ThePL/SQLwrappermethodstillworksfineasithasalreadybeenexecuted

once.4. ThePL/SQLwrappermethodgivesnooutput.

ExaminethefollowingTNSNAMES.oraandLISTENER.oraentriesandchoosethecorrectoption:

//TNSNAMES.ora

ORACLR_CONNECTION_DATA=

(DESCRIPTION=

(ADDRESS_LIST=


)

(CONNECT_DATA=

(SID=extproc)

(PRESENTATION=RO)

)

)

//LISTENER.ora

SID_LIST_LISTENER=

(SID_LIST=

(SID_DESC=

(SID_NAME=CLRExtproc)

(ORACLE_HOME=C:\ORCL\11.2.0\dbhome_1)

(PROGRAM=EXTPROC1521)

(ENVS=

"EXTPROC_DLLS=ONLY:C:\ORCL\product\11.2.0\dbhome_1\BIN\Ext.dll")

)

)

LISTENER=

(DESCRIPTION_LIST=

(DESCRIPTION=


(ADDRESS=(PROTOCOL=TCP)(HOST=localhost)(PORT=1521))

)

)

1. TheKEYvalueunderADDRESSofORACLR_CONNECTION_DATAmustbeextproc.2. TheSIDvalueunderCONNECT_DATAofORACLR_CONNECTION_DATAmustbe

CLRExtproc.3. TheKEYvalueunderADDRESSofLISTENERmustbeextproc.4. ThePROGRAMvalueofSID_LIST_LISTENERmustbeextproc.

Whichofthefollowingstatementsabouttheloadjavautilityaretrue?

1. ItgeneratesasharedlibraryfortheJavaprograms.2. ItloadstheJavaprogramintheOracleDatabase.3. TheloadjavautilityrequiresaJavacompilertorun.4. ItloadstheJavaclassfileintotheJavapoolinthedatabaseinstance.

ExternalprogramsinJavadon’trequirethesharedlibrariestobeexecutedfromPL/SQL.

1. True2. False

AnexternalCprogramlookslikethis:

#include<stdio.h>

#include<conio.h>

intGetDouble(intnum)

{

returnnum*2;

getch();

}

ThePL/SQLwrappermethodlookslikethis:

CREATEORREPLACEFUNCTIONF_GET_DOUBLE(P_NUMNUMBER)

RETURNNUMBER

ASEXTERNALLIBRARYNUMLIB

NAME"GETDOUBLE"

LANGUAGEC

PARAMETERS(P_NUMINT);

WhenyoucallthePL/SQLwrapper,yougetthefollowingexception:

DECLARE

*

ERRORatline1:

ORA-06521:PL/SQL:Errormappingfunction

ORA-06522:UnabletoloadsymbolfromDLL

ORA-06512:at"ORADEV.F_GET_DOUBLE",line1

ORA-06512:atline4

Identifythecauseforthisexception:

1. TheNUMLIBlibraryhasbeenincorrectlyplaced.2. TheCprogramhassyntacticalerrors.3. TheCprogramnameinthecallspecification(thePL/SQLwrapper)shouldbe

GetDoubleinsteadofGETDOUBLE.4. Theextprocprocessisnotworkingproperly.

Chapter6.VirtualPrivateDatabaseInformationsecurityisoneofthekeychallengesthatorganizationshavetoaddresstoprotectdataprivacyanditsregulation.Leakageofsensitiveinformationorunauthorizedaccesstodatamightleadtohazardousconsequences.Withthestringentprotocolsofdatadistributionandsteepriseoftheinternetusage,datasecuritycanposeatediousquestiontotheorganizations.Informationthatispronetoinvasionscanbepersonaldetails,financialdata,creditcardinformation,businessleads,oranintellectualproperty.Arelationaldatabasecanexposepotentialareasofinjectionintheformofnetworkaccess,overprivilegeduseraccounts,non-databasefileaccess,nonsanitizedinputs,andproliferationofproductiondatatounregulatedenvironments.Knowingthefatalconsequencesofdatabreaches,thedatasecuritysolutionsmustbeefficienttobypasstheattacksfromthedatabaselayer,network,andapplication.

Inthischapter,wewillwalkthroughanoverviewofOracle’sDatabaseSecuritysolution.WewillfocusontheimplementationofaVirtualPrivateDatabasetodevelopsecureapplications.Inaddition,wewillhighlightthekeysecurityenhancementsinOracleDatabase12c.

OracleDatabaseSecurityoverviewVirtualPrivateDatabaseOracleDatabase12cSecurityenhancements

OracleDatabaseSecurityoverviewOracleoffersacomprehensivesuiteofdatabasesecuritysolutionsthataimtosecurethedatabasesandapplicationsbyprotectingsensitiveinformation,detectingthreatsandattacks,andmanagingsecuritypoliciesalongthelinesoforganizationalcompliance.Thedefense-in-depthapproachofOraclecanbecategorizedunderpreventive,detective,andadministrativecontrolsthatensureallthevulnerableareasofanapplicationarecovered.Apowerfulsecuritystrategycanbedevelopedandlaiddownbyusingtherightmixofsecurityfeatures.Thefactorsimpactingtheformulationofasecuritystrategycanbethreatanticipation,datasensitivity,datadistributionanduserclassification,compliance,andinternalregulations.

Eachoftheabovecategoriesincludesvariousproductsandtechnicalfeatures.Thefollowingdiagrambifurcatesthesecuritypillarsintosecuritymeasures:

OracleDatabasesecurityfeatureunderthreecategories

TheOracleDatabaseSecuritysolutionincludesthefollowingdatabaseproducts:

OracleAdvancedSecurity:OracleAdvancedSecurityisalicensedoptionavailablewiththeOracleDatabaseEnterpriseEdition.Thisoptionincludesvariousfeaturesthatcanbeimplementedatthedatabaseleveltopreventdatahackingandreducethedirectexposureofsensitiveinformationtoanunauthorizeduser.IthelpsprotectthedatafrommaliciousattacksandcomplywiththesecurityregulationslikePaymentCardIndustryDataSecurityStandard(PCI-DSS)andHealthInsurancePortabilityandAccountabilityAct(HIPAA).Forexample,youcanencryptthecustomer’sbankaccountinformationinthedatabase.Similarly,thesensitiveinformationinthedatabasecanberedactedforsupportorcallcenterexecutives.

TheOracleAdvancedSecurityoptionincludes:

DataRedaction:TheDataRedactionfeaturewasintroducedinOracleDatabase12ctoapplyon-the-flymaskingpoliciestothesensitiveinformationinthedatabase.ThefeaturehasbeenbackportedtoOracleDatabase11.2.0.4.Dataredactioncanbeahandyfeatureasitiscost-efficientanddynamicallyobfuscatesthedata.ThisfeatureiscoveredindetailintheOracleDatabase12cSecurityEnhancementssectionofthischapter.TransparentDataEncryption(TDE):Theencryptionfeaturepreventsthedata,whichislyinginstorage,fromoutsideattacks.Thedataisstoredinanencryptedformat,whichgetsauto-decrypted.ItisinstalledatthetimeoftheOracleDatabasesoftwareinstallation.Itisaneasy-to-implementtransparentsolutionandrequiresnochangestotheexistingSQLqueries.

NoteSecurefileencryptionispartoftheAdvancedSecurityoption.

TheotherfeaturesincludedundertheAdvancedSecurityoptionareDataPumpExportfileencryptionandRMANBackupencryptiontodisk.

VirtualPrivateDatabase(VPD):ThisisasecurityfeatureavailableinOracleDatabaseEnterpriseEditionthatcontrolsthedatavisibilityandaccessibilitydependingonthedatabaseuserauthorization.FirstintroducedinOracle8i,thefeatureworkswithVPDpoliciesandsessioncontexts.Allqueriesissuedbyauserareappendedbyanadditionalpredicatetorestricttherowsintheresultset.ItisalsoknownasFineGrainedAccessControlorRowLevelSecurity.RealApplicationSecurity(RAS):ThisfeaturewasintroducedinOracleDatabase12ctosupportthediversifiedsecurityrequirementsinanenterpriseapplicationmodel.ItpresentsanadvancedversionoftheVirtualPrivateDatabasetechnology.Notonlythedatavisibility,aRealApplicationSecuritypolicyalsoallowsyoutocontrolthetransactionalpermissionsontheapplicationobjects.Itisoneofthesmartestsecuritysolutionsthatcancontroltheprivilegesofanapplicationuseronthebusinessobjects.OracleKeyVault(OKV):OracleKeyVaultprovidesarobustkeymanagementplatformthatcanbeusedasthecentralizedrepositoryofTDEmasterkeys,Oraclewallets,Javakeystores,SSHkeys,andothersecuritycredentialfiles.TheOKVstoreallowstheend-to-endadministrationofthekeylifecycleincludingcreation,retention,andkeyrotation.OracleDatabaseVault:OracleDatabaseVaultenablesasecuritysolutiontosafeguardtheapplicationdatafromprivilegeddatabaseusersandadhocaccess.Amultifactordatabasevaultpolicyimposesdeterrentcontrolsontheuseraccesstothedatabaseandreportsviolations,ifany.ItisapowerfulproactivesolutionthathelpsinreducingtheattacksurfaceforhighlyprivilegeduserslikeSYSTEM,SYSDBA,orauserwithalargesetofrolesandprivileges.OracleprovidesdefaultvaultpoliciesfortheOracleE-BusinessSuite(versions11.5.10,12.0,and12.1),OraclePeopleSoftapplication,OracleSiebelCRM(version7.7andhigher),andSAPapplications.PrivilegeAnalysis:ThenewfeatureinOracleDatabase12canalyzestheprivileged

users,roles,anddatabasetoreporttheusedandunusedprivileges.Basedontheanalysis,thesecurityadministrator(ortheDBA)candeterminewhethertoretainorrevoketheprivilegesofthedevelopersordatabaseusers.Thisfeatureisquiteimportantfromthepointofviewofapplicationsecurityandhelpsreducetherisksfrominternalusers.OracleDataMaskingandSubsetting:TheOracleDataMaskingandSubsettingpackmaskstheoriginalcopyoftheapplicationdatabyphysicallyobfuscatingthesensitiveinformationineitherthecompleteapplicationdatabaseorjustitssubset.Themaskeddatacanthenbeproliferatedforanalytical,testing,orregulatorypurposes.Thesensitiveinformationandreferentialintegritymodelcanbediscoveredbasedontheprebuiltdatapatterns.Aportionofalargedatabasecanbeextractedbasedonfactorssuchaspercentage,thenumberofrows,orcolumnpredicates.Thispackcontainsavarietyofmaskingformatsandtransformationsthatcanbeappliedtotheapplicationdata.OracleLabelSecurity(OLS):OracleLabelSecurity,firstintroducedinOracle8i,isadatabaseoptionavailableintheenterpriseeditionoftheOracleDatabase.Itenablestheclassificationofdatabylabels.Thesecuritypoliciescontroltheuseraccessprivilegesandauthorizationontheapplicationbythedatalabels.Thisoptionisveryusefulinimplementingmultilevelsecurityinlargelegacyapplications.OracleAuditVaultandDatabaseFirewall(AVDF):ThisproductcanbedeployedinallOracleDatabaseeditionsandnon-OracleproductssuchasMicrosoftSQLServer,IBMDB2forLUW,SAPSybaseASE,MySQLdatabasesandOracleBigDataAppliance.YoucandefinetherulestocaptureandblocktheunauthorizedSQLaccesstotheapplicationdata.Anotherfeatureofthisproductistheconsolidationofthedatabaseauditwiththesystemandnetworkauditinformation,whichthengeneratesalertsandreports.

NoteStrongauthenticationservicessuchasKerberos,PKI,andRADIUSalongwithnetworkencryptionareavailableinalltheeditionsoftheOracleDatabase.

Fine-GrainedAccessControlInanenterpriseapplication,userisolationorrole-basedmultitenancyensuresthatdataisaccessedbytheauthorizedusersonly.InaSoftwareasaService(SaaS)modelapplication,tenantisolationisoneoftheprimedemands.Applicationusersareauthorizedtoaccessonlytheirworldofdataandnotpeekintootheruser’sdata.

Fine-grainedaccesscontrol(FGAC)enablestheenforcementofsecuritypoliciesontheaccessofrowsandcolumnsbasedontheuser’sroleandauthorization.Forexample,anHRrepresentativeisauthorizedtoviewthedetailsofemployeesthatbelongonlytohisvertical.Similarly,arelationshipofficerinabankisauthorizedtoaccesstheaccountdetailsofthosecustomersthatbelongtohisbranch.TheFGACfeatureprovidesyouwiththemechanismtoexposetheauthorizedpieceofdataonlytotheapproveduser.

HowFGACworksFine-grainedaccesscontrolenablesthecreationofsecuritypoliciesthatcanbeassociatedwithatableorview.Uponinvocation,thesecuritypolicyevaluatesthepolicyfunctionthatreturnsapredicateclause,whichisdynamicallyappendedtotheSQLqueriesissuedbytheuser.Thus,theuserviewsonlytheauthorizedrowsfromthetableoraview.Thesecuritypolicycanlimiteitherrowsorcolumnsorboth.

Inthefollowingfigure,auserfromdepartment10queriestheEMPtable.HeissuesaSELECTstatementtoviewtheemployeedetails.OracleinvokestheFGACpolicyattachedtotheEMPtableandappendsapredicate(thatis,theWHEREclause)totheSELECTquery.ThemodifiedSELECTqueryisthenexecutedintheHRschemaofthedatabase.

HowFine-GrainedAccessControlworks

Thefollowingarethesalientfeaturesoffine-grainedaccesscontrol:

OracleprovidestheDBMS_RLSpackageforthemanagementofsecuritypoliciessuchascreation,drop,enable,anddisableApolicycanbesettobeinvokedonlywhengivencolumnsareaccessedMultiplesecuritypoliciescanbeassociatedwithatableorviewAllsecuritypoliciesandthepredicatesareappendedwiththeANDclause

VirtualPrivateDatabaseTheworkingprincipleoftheVirtualPrivateDatabasetechnologyisthatusersshouldhaveisolatedanddistinguisheddataaccess.VirtualPrivateDatabase(VPD)isafeaturethatisbuiltonfine-grainedaccesscontrolandusesapplicationcontextstodefineandaddthepredicatestotheSQLqueries.SimilartoFGAC,VirtualPrivateDatabaselaysdownthesecurityframeworkthroughthesecuritypoliciesintheOracleDatabaseandassociatesthemdirectlytotables,views,orsynonyms.Thesecuritypoliciesactasasafetynetontheobjects,andbynomeanstheycanbebypassed.

HowdoesVirtualPrivateDatabasework?WheneverauserissuesanSQLqueryagainstaVirtualPrivateDatabaseprotectedtable,Oracleinvokesthepolicyandevaluatesthepolicyfunction.ThepolicyfunctionisaPL/SQLfunctionthatreturnsapredicateoraWHEREclause.Thequeryisthenrewrittenusingdynamicviewstoaddthepredicateclause.Themodifiedqueryisexecutedagainstthedatabaseserverandtheresultsetisreturnedtotheuser.ThepredicateortheWHEREclauseparticipatesintheexecutionofthequery,thatis,thecolumnindexeswillimpactthequeryexecutionplan.

NotethattheVirtualPrivateDatabaseprotectsonlytheSELECT,INDEX,andDMLoperations(INSERT,UPDATE,andDELETE).Itdoesn’tworkwithDDL’slikeTRUNCATEorALTERTABLEstatements.

Column-levelVirtualPrivateDatabaseRow-levelsecuritycanalsobeimposedontablesandviewswheneverauserselectssensitivecolumns.Thesensitivecolumnscanbespecifiedatthetimeofthepolicycreation,thatis,theSEC_RELEVANT_COLSparameteroftheDBMS_RLS.ADD_POLICYprocedure.

Thecolumn-levelpolicyworksonlyfortheSELECTqueries.Whenauserselectssensitivecolumns(implicitlyorexplicitly),thenon-authorizedrowsareexcludedfromtheresultset.Forexample,ifanHRrepresentativequeriespublicinformationsuchasthenameanddepartmentofemployees,thequerywilllistalltherecordsfromthetable.IfheattemptstoselectthesecuredcolumnslikeSAL,theresultsetwillbelimitedbytherow-levelsecuritycondition.

YoucanincludealltherowswiththesensitivecolumnvaluesmarkedasNULL.ItcanbeachievedbyspecifyinganattributeknownasSEC_RELEVANT_COLS_OPTintheDBMS_RLS.ADD_POLICYprocedure.

VirtualPrivateDatabasewithOracleDatabase12cMultitenantVirtualPrivateDatabaseissupportedwithinapluggabledatabase.Youcannotcreateasecuritypolicyintherootcontainer,thatis,thecontainerdatabase.

VirtualPrivateDatabasecomponentsTheVPDtechnologymakesuseoftheapplicationpackage,policyfunction,applicationcontext,andtheDBMS_RLSpackagetoaddpolicies.Inthefollowingsection,wewilldiscussthebuildingblocksoftheVirtualPrivateDatabaseimplementation.

ApplicationContextAVirtualPrivateDatabaseimplementationwithapplicationcontextsisusefulwhenworkingwithmultiplesecurityattributes.Forexample,inanorganization,thedataviewauthorizationmaybedifferentfordifferentjobroles.Inamanufacturingunit,Asupervisorcanbeauthorizedtoquerytheglobalpartswhileanexecutivecanseeonlythelocalparts.Insuchcases,thejobrolecanbeacontextattributewhosevaluecanbeusedinthepredicateclausereturnedbythepolicyfunction.

Applicationcontextsaresessionvariablesthatholdtheuserandsessioninformationsecurely.Contextattributesarestoredaskey-valuepairsunderagivennamespace,whichisalsoknownasalabel.USERENVisasystem-definednamespaceintheOracleDatabasethatcanprovidesessioninformationsuchasDB_NAME,SESSION_USER,andothers.User-definedapplicationcontextscanbecreatedbyaSYSDBAoruserswiththeCREATEANYCONTEXTprivilegebyusingatrustedapplicationpackage.

Anapplicationcontextcanbeeitherdatabasesession-based,clientsession-based,orglobal.

Adatabasesession-basedapplicationcontextisaccessibleonlywithinadatabaseuser’ssession.Itsattributesandvaluesarestoredinasessioncache,UserGlobalArea(UGA).Thedatabasesession-basedapplicationcontextscaneitherbeinitializedlocallyfromthesession,externallyusingadatabaselink,OCIinterfaceorjobqueueprocess,orgloballyfromacentralizeddirectoryusingtheOracleInternetDirectory.Youcanquerythedatabasesession-basedcontextattributesfromtheSESSION_CONTEXTdictionaryview.

Aclientsession-basedapplicationcontextisinitializedusingOCIfunctions(OCIAppCtxSet)andisstoredinUserGlobalArea(UGA)undertheCLIENTCONTEXTnamespace.Theapplicationcansetthenon-databaseattributeswithinthecontextsandusethemduringpolicycreation.Ensurethatthedatabasesessionandclientsession-basedapplicationcontextsdonotconflictwitheachother.

AglobalapplicationcontextcanbeaccessedbyallthedatabaseusersessionsinasingleinstanceorRACenvironment.ThecontextattributesandtheirvaluesarestoredinSystemGlobalArea(SGA),whichcanbequeriedfromtheGLOBAL_CONTEXTdictionaryview.

ThefollowingSQLqueriesthedatabasenamefromtheUSERENVnamespaceusingtheSYS_CONTEXTfunction:

/*QuerythedatabasenamefromUSERENVnamespace*/

SELECTSYS_CONTEXT('USERENV','DB_NAME')

FROMdual

/

SYS_CONTEXT('USERENV','DB_NAME')

-------------------------------------------------------

orcl

Youcancreatedatabasesession-basedapplicationcontextsusingtheCREATECONTEXTstatement,asperthefollowingsyntax:

CREATECONTEXT[context_name]

USING[trusted_package]

INITIALIZED[EXTERNALLY|GLOBALLY]

ACCESSED[LOCALLY|GLOBALLY]

TrustedpackageisaPL/SQLpackageorstoredprocedurethatcontrolsthevaluesofthecontextattributes.Adatabasesession-basedcontextcanbeinitializedlocally,externallyorglobally.ThecontexttypecanbeACCESSEDGLOBALLYforglobalapplicationcontextsorACCESSEDLOCALLY(default)forsession-basedapplicationcontexts.Thefollowingexampleshowsthecreationofacontextusingatrustedpackage:

/*ConnectasSYSDBA*/


Connected.

/*GrantCREATEANYCONTEXT,DROPANYCONTEXTprivilegestoSCOTT*/

GRANTCREATEANYCONTEXT,DROPANYCONTEXTTOSCOTT

/

Grantsucceeded.

/*ConnecttoSCOTTuser*/

CONNscott/tiger

Connected.

YoucancreatethetrustedPL/SQLprogrambeforeoraftercreatingthecontext.ThefollowingPL/SQLprocedureP_APP_CONTEXTusestheOraclesuppliedpackageDBMS_SESSIONtocreateacontextnamespaceandmemberattributes.

/*Createthestoredproceduretosetthecontextattribute*/

CREATEORREPLACEPROCEDUREp_app_context(p_valVARCHAR2)

IS

BEGIN

/*CreateanamespaceDEMO_CONTEXT*/

DBMS_SESSION.SET_CONTEXT(

NAMESPACE=>'DEMO_CONTEXT',

ATTRIBUTE=>'COUNTRY',

VALUE=>P_VAL);

END;

/

ThePL/SQLprocedurecannowbeusedtocreatetheapplicationcontext.

/*Createthecontext*/

CREATECONTEXTdemo_contextUSINGp_app_context

/

Contextcreated.

Now,usethetrustedprogramtosetthevalueoftheCOUNTRYcontextkey.Usethesameprogramtomodifythecontextattributevalue.

/*CallP_APP_CONTEXTtosetcontextvalue*/

EXECp_app_context('LUXEMBOURG')

/


/*QuerytheCOUNTRYcontext*/

SELECTSYS_CONTEXT('DEMO_CONTEXT','COUNTRY')

FROMDUAL

/

SYS_CONTEXT('DEMO_CONTEXT','COUNTRY')

----------------------------------------------------------------

LUXEMBOURG

VirtualPrivateDatabasepolicyfunctionTheVirtualPrivateDatabasepolicyfunctionisaPL/SQLfunctionthatisusedtoconstructthepredicate(orWHERE)clause.Thepolicyfunctionisspecifiedduringpolicycreationthatgetsexecutedatthetimeofpolicyenforcement.Notethatthefunctionexecutionperformancedirectlyimpactsthequeryperformance.

Thefollowingarethefeaturesofthepolicyfunction:

Theschemanameanddatabaseobjectnamearemandatoryparameters(andinthesamesequence)tothepolicyfunction.Uponexecution,theparametervaluesaresuppliedbytheDBMS_RLSpackage.Thefunctionmustreturnavalidpredicateinstringformat.ThefunctionmustnotperformSELECTorDMLonthetabletobeprotectedthroughtheVirtualPrivateDatabase.

PolicytypesYoucanspecifyapolicytypetooptimizetheperformanceofaVirtualPrivateDatabasesecuritypolicy.Thepolicyperformanceislimitedbytheresourcesconsumedduringtheexecutionofthepolicyfunctionandfrequencyofitsexecution.

AVirtualPrivateDatabasepolicycanbeSTATIC,DYNAMIC,SHARED_STATIC,CONTEXT_SENSITIVE,orSHARED_CONTEXT_SENSITIVE.ThefollowingtableshowsthedifferentVPDpolicytypes:

Policytype Comments Whentouse

STATIC

SamepredicateforallthequeriesPredicateclauseiscachedinSGA

Usedwhenallthequeriesonatablehaveamandatorypredicateandperformanceisthepriority.

Policyfunctionisexecutedforeveryquery Usedwhenthepredicateconditionchangesforeach

DYNAMIC(Default) Noperformanceoptimization

queryissuedontheVirtualPrivateDatabaseprotectedobjectortable.

SHARED_STATIC

PolicyshareableacrossschemaobjectsPredicateclauseiscachedinSGA

Usedwhenmultipletablesorviewshavethesamecolumns.

CONTEXT_SENSITIVE

PolicyisapplicableonlytoafixedvalueoftheapplicationcontextIncludethenamespaceandattributeparametersinthepolicydefinition

Usedwhenthepredicatevariesbytheuserorgroup.

SHARED_CONTEXT_SENSITIVE

Sameasthecontext-sensitivepolicyPolicycanbesharedamongmultipleobjects

Usedwhenthepredicatevariesbytheuserandcanbesharedbymultipledatabaseobjects.

TheDBMS_RLSpackageThesecuritypoliciesareenforcedusingtheOracle-suppliedDBMS_RLSpackage.Itcanbeusedtoadd,drop,orrefreshasecuritypolicy,enableordisableapolicy,andhandlethepolicygroups.ItisownedbytheSYSuserandavailableinenterpriseeditiononly.

NoteForcompletedetails,itisrecommendedthatyourefertotheOracleDatabase12cdocumentationathttps://docs.oracle.com/database/121/ARPLS/d_rls.htm.

ThefollowingtableliststhesubprogramscontainedintheDBMS_RLSpackage:

Subprogram Description

ADD_POLICY Addsafine-grainedaccesscontrolpolicytoatable,view,orsynonym

DROP_POLICY Dropsafine-grainedaccesscontrolpolicyfromatable,view,orsynonym

REFRESH_POLICY Causesallthecachedstatementsassociatedwiththepolicytobereparsed

ENABLE_POLICY Enablesordisablesafinegrainedaccesscontrolpolicy

CREATE_POLICY_GROUP Createsapolicygroup

ADD_GROUPED_POLICY Addsapolicyassociatedwithapolicygroup

ADD_POLICY_CONTEXT Addsthecontextfortheactiveapplication

DELETE_POLICY_GROUP Deletesapolicygroup

DROP_GROUPED_POLICY Dropsapolicyassociatedwithapolicygroup

DROP_POLICY_CONTEXT Dropsadrivingcontextfromtheobjectsothatitwillhaveonelessdrivingcontext

https://docs.oracle.com/database/121/ARPLS/d_rls.htm

ENABLE_GROUPED_POLICY Enablesordisablesarow-levelgroupsecuritypolicy

DISABLE_GROUPED_POLICY Disablesarow-levelgroupsecuritypolicy

REFRESH_GROUPED_POLICY Re-parsestheSQLstatementsassociatedwitharefreshedpolicy

DemonstrationThissectiondemonstratestheimplementationofaVirtualPrivateDatabasetoenforcerow-levelandcolumn-levelsecurity.

Let’ssupposethatSCOTTisamasteruserthatownstheemployeedetails.Allothersubusersareauthorizedtoviewthedetailsoftheemployeesthatbelongtotheirjobroles.Forexample,CLERKisauthorizedtoviewonlytheclerk’sdetailswhileSALESisauthorizedtoviewonlysalesmandata.

Let’spreparethetestenvironmentbycreatingthetestusersandgrantingthemrequiredprivileges:

/*CreateuserCLERK,MGR,SALES.GrantCONNECT,RESOURCEroles*/

CONNsys/oracleassysdba

CREATEUSERclerkIDENTIFIEDBYclerk

/

CREATEUSERmgrIDENTIFIEDBYmgr

/

CREATEUSERsalesIDENTIFIEDBYsales

/

GRANTCONNECT,RESOURCETOclerk

/

GRANTCONNECT,RESOURCETOmgr

/

GRANTCONNECT,RESOURCETOsales

/

GRANTEXECUTEONdbms_rlsTOpublic

/

GRANTCREATEANYCONTEXTTOscott

/

GRANTCREATEPUBLICSYNONYMTOscott

/

Let’screatetheMYJOBcontextusingatrustedprogram:

CONNscott/tiger

/*CreatethecontextMYJOB*/

CREATECONTEXTmyjobUSINGscott.job_context

/

ThefollowingJOB_CONTEXTproceduresetstheMYJOBcontextattributes,basedonthecurrentsessionuser.Thecontextattributevaluesshouldmatchtheexpectedvaluetobeusedinthequerypredicates:

/*CreatethePL/SQLprocedure*/

CREATEORREPLACEPROCEDUREjob_contextIS

BEGIN

/*Setthecontextbasedonthesessionuser*/

IFSYS_CONTEXT('USERENV','SESSION_USER')='CLERK'THEN

DBMS_SESSION.SET_CONTEXT('myjob','role','CLERK');

ELSIFSYS_CONTEXT('USERENV','SESSION_USER')='SALES'THEN

DBMS_SESSION.SET_CONTEXT('myjob','role','SALESMAN');

ELSIFSYS_CONTEXT('USERENV','SESSION_USER')='MGR'THEN

DBMS_SESSION.SET_CONTEXT('myjob','role','MANAGER');

ENDIF;

END;

/

AsthisprocedurewillbeaccessedbySALES,CLERK,andMGR,let’screateapublicsynonymandgranttheexecuteprivilegetotheusers:

/*CreatesynonymforJOB_CONTEXTprocedure*/

CREATEPUBLICSYNONYMjob_contextFORscott.job_context

/

GRANTEXECUTEONscott.job_contextTOclerk,mgr,sales

/

/*GrantselectprivilegeonEMPtabletotheusers*/

GRANTSELECTONempTOclerk,mgr,sales

/

Tosetthecontextatthetimeofthedatabaselogon,let’screatealogontrigger.Thistriggercallsthecontextsettingprocedure:


/*Createalogontrigger*/

CREATEORREPLACETRIGGERscott.set_security_context

AFTERLOGONONDATABASE

BEGIN

scott.job_context;

END;

/

Now,it’stimetocreatetheVirtualPrivateDatabasepolicyfunction.Itlaysdownthelogicofrow-levelsecuritybyconstructingthepredicateclause.Inthiscase,thesecuritypolicyvirtuallypartitionsthedataviewbyjobroles.ThepredicateusestheSYS_CONTEXTfunctiontoretrievethejobrolecorrespondingtothesessionuser.

CONNscott/tiger

/*Createpolicyfunction*/

CREATEORREPLACEFUNCTIONfun_vpd

(schemaownerVARCHAR2,objectnameVARCHAR2)

RETURNVARCHAR2IS

BEGIN

/*Returnthepredicateclause*/

RETURN'job=SYS_CONTEXT(''myjob'',''role'')';

END;

/

/*Createpublicsynonymforthepolicyfunction*/

CREATEPUBLICSYNONYMfun_vpdFORscott.fun_vpd

/

GRANTEXECUTEONscott.fun_vpdTOclerk,mgr,sales

/

ThefinalstepisthecreationofpolicyontheobjectusingtheDBMS_RLS.ADD_POLICYprocedure:

connscott/tiger

BEGIN

DBMS_RLS.add_policy(

object_schema=>'SCOTT',

object_name=>'EMP',

policy_name=>'VPD_RLS',

function_schema=>'SCOTT',

policy_function=>'FUN_VPD',

statement_types=>'SELECT');

END;

/

Let’sconnecttotheMGRuserandverifytheVirtualPrivateDatabaseinoperation:

connmgr/mgr

SELECTempno,ename,job,mgr,deptno

FROMscott.emp

/

EMPNOENAMEJOBMGRDEPTNO

----------------------------------------

7566JONESMANAGER783920

7698BLAKEMANAGER783930

7782CLARKMANAGER783910

TheCLERKusercanquerythedetailsofonlythoseemployeesthatareclerks.Similarly,theotheruserscantrytologinthedatabaseandverifythedataview:

connclerk/clerk


FROMscott.emp

/


-----------------------------------------

7369SMITHCLERK790220

7876ADAMSCLERK778820

7900JAMESCLERK769830

7934MILLERCLERK778210

AndthentheSALESuser:

connsales/sales


FROMscott.emp

/


--------------------------------------------

7499ALLENSALESMAN769830

7521WARDSALESMAN769830

7654MARTINSALESMAN769830

7844TURNERSALESMAN769830

Youcanenforceacolumn-levelpolicybyspecifyingthesensitivecolumnsatthetimeofthepolicycreation.ThefollowingPL/SQLblockdropsthelastVirtualPrivateDatabasepolicyandcreatesanewonetoenforcetherow-levelsecurity:

connscott/tiger

BEGIN

/*Droptherow-levelpolicy*/

DBMS_RLS.DROP_POLICY('SCOTT','EMP','VPD_RLS');

/*CreateacolumnlevelVPDpolicy*/

DBMS_RLS.ADD_POLICY(


object_name=>'EMP',

policy_name=>'VPD_COLUMN',


sec_relevant_cols=>'sal,comm');

END;

/

TheprecedingsecuritypolicyspecifiesthatwheneverauserwilltrytoquerytheSALandCOMMcolumnsoftheEMPtable,therow-levelsecuritywillbeenforced.Let’sverifythisstatementbyconnectingtotheMGRuserandqueryingtheemployeerecords:

CONNmgr/mgr

/*Selectnon-sensitivecolumnsfromEMPtable*/

SELECTempno,deptno,job

FROMscott.emp

/

EMPNODEPTNOJOB

------------------------

736920CLERK

749930SALESMAN

752130SALESMAN

756620MANAGER

765430SALESMAN

769830MANAGER

778210MANAGER

778820ANALYST

783910PRESIDENT

784430SALESMAN

787620CLERK

790030CLERK

790220ANALYST

793410CLERK

14rowsselected.

NotethattheprecedingquerydisplaysalltheemployeesbecausetheSELECTquerydidn’tprojecttheSALandCOMMsensitivecolumns.IfthequeryhadcontainedtheSALcolumn,theoutputwouldhavebeenasfollows:

/*SelectsensitivecolumnsfromEMPtable*/

SELECTempno,deptno,sal,job

FROMscott.emp

/

EMPNODEPTNOSALJOB

----------------------------------

7566202975MANAGER

7698302850MANAGER

7782102450MANAGER

Intheprecedingoutput,theemployeerecordswiththesensitivecolumnsarerestrictedinthequeryoutput.However,youcanstilllistalltheemployeesandmasktheSALandCOMMsensitivecolumnswithNULLsbysettingtheSEC_RELEVANT_COLS_OPTattributetoDBMS_RLS.ALL_ROWS:

CONNscott/tiger

BEGIN

/*Dropthepreviouspolicy*/

DBMS_RLS.DROP_POLICY('SCOTT','EMP','VPD_COLUMN');

/*Createanewcolumn-levelpolicy*/

DBMS_RLS.ADD_POLICY(


object_name=>'EMP',

policy_name=>'VPD_COLUMN',


sec_relevant_cols=>'sal,comm',

sec_relevant_cols_opt=>DBMS_RLS.ALL_ROWS);

END;

/

Withtheprecedingsecuritypolicy,theoutputoftheSELECTquerywillbeasfollows:

CONNmgr/mgr

/*SelectsensitivecolumnsfromEMPtable*/

SELECTempno,ename,job,sal,deptno

FROMscott.emp

ORDERBYjob

/

EMPNOENAMEJOBSALDEPTNO

------------------------------------------------------------

7788SCOTTANALYST20

7902FORDANALYST20

7934MILLERCLERK10

7900JAMESCLERK30

7369SMITHCLERK20

7876ADAMSCLERK20

7698BLAKEMANAGER285030

7566JONESMANAGER297520

7782CLARKMANAGER245010

7839KINGPRESIDENT10

7844TURNERSALESMAN30

7654MARTINSALESMAN30

7521WARDSALESMAN30

7499ALLENSALESMAN30

14rowsselected.

VirtualPrivateDatabasefeaturesandbestpracticesThefollowingarethefeaturesandbestpracticesthatcanbefollowedwhileworkingwithaVirtualPrivateDatabase:

YoucannotqueryaVirtualPrivateDatabaseprotectedtableasSELECTFORUPDATEbecauseofthequeryrewriteimplementation.However,theFORUPDATEuserquerymayworkprovidedtheVPDimpliedinlineviewforthequeryisnotacomplexone,thatis,anon-analyticquery,withnoDISTINCT,nocursorexpression,noSEToperator.SYSuserisexemptedfromtheVirtualPrivateDatabasesecuritypolicies.However,theSYSDBAactionscanbemonitoredusingDatabaseVault.UserswiththeEXEMPTACCESSPOLICYsystemprivilegeareexemptfromtheVirtualPrivateDatabasesecuritypolicies.Thisprivilegemustbeusedjudiciouslyasitbypassesallthefine-grainedsecuritycontrols.Thepolicyfunctionshouldbeexecutedwithdefiner’srightsinmajorcasestoavoidanyuncertaintyduetoprivileges.AvoidusingouterjoinsandtheANSIjoinoperationsontheVirtualPrivateDatabaseprotectedtables.Ifyouareusingedition-basedredefinitioninyourapplication,youcanassociateaneditioningviewtoapplytheVirtualPrivateDatabasepoliciesacrossalltheeditions.VirtualPrivateDatabaseworkswithflashbackquery.YoucanquerythebusinessdatatoapasttimeorolderSCNusingthemostrecentsecuritypolicies.Duringadirectpathexportoperation,theOracleVirtualPrivateDatabasepolicies(andOracleLabelSecuritypolicies)arenotenforced.AschemalevelexportoperationfailsiftheschemacontainsaVPDprotectedobject.Inascenariowhereauserhasavalidjustificationtobypasssecuritypolicies,hecanbegrantedEXEMPTACCESSPOLICYprivilege(withoutWITHADMINOPTION)toignoreVPDpolicies.

VirtualPrivateDatabasemetadataOraclecapturesthestaticanddynamicdetailsoftheVPDpoliciesindictionaryviews.YoucanquerythefollowingdictionaryviewstofindthemetadataabouttheVirtualPrivateDatabasesecuritypolicies:

Dictionaryview Comments

[ALL|USER|

DBA]_POLICIES

Theviewcapturesthesecuritypolicyonobjectsaccessibletoauser,ownedbyauser,orwithinadatabase.

[ALL|USER|

DBA]_POLICY_ATTRIBUTES

Theviewcapturestheapplicationcontextnamespaces,theirattributes,andtheirassociationwiththeVirtualPrivateDatabasepolicy.

[ALL|USER|

DBA]_POLICY_CONTEXTSTheviewcapturesinformationaboutthedrivingcontextsfortheobjects.

[ALL|USER|

DBA]_POLICY_GROUPSTheviewcapturesinformationaboutthepolicygroupsontheobjects.

[ALL|USER|

DBA]_SEC_RELEVANT_COLS

Theviewcapturesthespecificationsofthecolumn-levelVirtualPrivateDatabasepolicyontheobjects.

V$VPD_POLICY

Thedynamicviewcapturesinformationaboutthesecuritypolicyassociatedwiththecachedcursors.Inamultitenantenvironment,theviewshowsinformationaboutthecurrentpluggabledatabase.It’sextremelyusefulintroubleshootingpolicyexecution.

ThefollowingquerygivesthepredicateappliedtothequeriesexecutedagainsttheVirtualPrivateDatabaseprotectedtableownedbytheSCOTTuser:

connectsys/oracleassysdba

SELECTobject_name,

policy,

s.sql_text,

predicate

FROMv$vpd_policyvp,v$sqls

WHEREvp.sql_id=s.sql_id

ANDobject_owner='SCOTT'

/

OBJECT_NAMEPOLICYSQL_TEXTPREDICATE

---------------------------------------------------------------

EMPVPD_COLUMNselect*fromscott.empjob=

SYS_CONTEXT('myjob','role')

ForfurtherinformationabouttheVPD_COLUMNpolicy,youcanrefertotheUSER_POLICIESdictionaryview:

connectscott/tiger

SELECTpolicy_name,

policy_type,

static_policy,

function,

pf_owner

FROMUSER_POLICIES

/

POLICY_NAMEPOLICY_TYPESTAFUNCTIONPF_OWNER

----------------------------------------------------

VPD_COLUMNDYNAMICNOFUN_VPDSCOTT

Policyutilities—refreshanddropThepolicyutilityactivitiessuchasrefreshingordroppingcanbedonethroughtheDBMS_RLSpackagesubprograms.Refreshingapolicyinheritsthelatestchangesmadetothepolicyanditsdependents.Apolicyrefreshisrequiredwhentheunderlyingreferencedobjectsofthepolicyundergoanychangethatinvalidatesthedependentobjects.Duringthepolicyrefreshprocess,allthecachedstatementsassociatedwiththepolicyareparsedagain.Apolicythatisalreadydisabledcannotberefreshed.

AVirtualPrivateDatabasepolicycanbedroppedusingtheDROP_POLICYsubprogramoftheDBMS_RLSpackage:

EXECDBMS_RLS.DROP_POLICY('SCOTT','EMP','VPD_COLUMN')

/

OracleDatabase12cSecurityenhancementsOracleDatabase12cintroducedanumberoffeaturesandenhancementstofurtherstrengthenthein-depthsecuritycollateral.Inthissection,youwillunderstandsomeofthekeysecurityenhancementsandfeaturesinOracleDatabase12c.Thefollowingisasummaryofthenewsecurityfeatures:

RealApplicationSecurity(RAS):OracleDatabase12cintroducesadataauthorizationsolutiontoprovideend-to-endsecurityinamultitierapplicationarchitecture.Youcannowdeclareandenforcetheapplication-levelsecuritypoliciesinthedatabasekernel.TheRASsecuritymodelunderstandstheapplication-levelsecuritypolicyconstructs,suchasapplicationusers,privileges,androleswithinthedatabase,andenforcesthesecuritypoliciesinthecontextoftheapplication.Aswellasdataaccess,RAScanhelptheapplicationstosecuretheaccesscontroloperationsofanapplicationuser.OracleDataRedaction:TheDataRedactionfeaturemasksthesensitivedataon-the-flybeforeitisdisplayedtotheuser.Thisfeatureprovidesarichlibraryformaskingthesensitiveinformationwhilethedatainthestorageremainsinanactual,thatis,unmaskedformat.Roleandprivilegeanalysis:Privilegeanalysishelpstoenhanceoperationalsecuritybyidentifyingtheleastsetofprivilegestorunanapplication.Duringapplicationdevelopment,youmayhavegrantedsystemprivilegesSELECTANYTABLEtoauserorobjectprivilegestothePUBLICrole.However,beforemovingittoproduction,youmustverifythesecurityaspectoftheapplicationbyretainingtherequiredprivilegesandrevokingtheunnecessaryones.Youcannowanalyzetheroles,usersorcontexts,sessionsordatabasetodetectusedandunusedprivileges.Aprivilegeisconsideredasunusedifitisnotutilizedforcompilationorrun-timeoperations.

AuserwiththeCAPTURE_ADMINrolecankick-offaprivilegeanalysisoperation.NotethataSYSusercannotbeanalyzedunderprivilegeanalysis.

UnifiedAuditing:OracleDatabase12cintroducesaunifiedaudittrailwhichresolvesthepaintomaintaindifferentstoresofauditinformation.ThenewUNIFIED_AUDIT_TRAILdatadictionaryviewreplacesthepreviousauditingviewsandconsolidatestheauditinformationfromallthesources.ThenewAUDIT_VIEWERandAUDIT_ADMINrolesenabletheseparationofdutyandprovideeasymanagementofauditingwithinthedatabase.Thenewauditingframeworksupportsconditionalauditingtopreventtheauditingofirrelevantoperations.NewadministrativeprivilegessuchasSYSBACKUP,SYSDG,andSYSKM:Thesearethenewprivilegesfordedicatedtaskslikebackup,dataguardoperations,andkeymanagementinordertoreducedependencyonSYSDBAandenabletheseparationofduties.TheREADobjectprivilegeandtheREADANYTABLEsystemprivilege:Youcannow

granttheREADobjectprivilegethatallowsausertoquerytables,views,materializedviews,andsynonyms.ThedifferencebetweentheSELECTandREADobjectprivilegesisthatSELECTallowsausertolockthetabledatausingtheLOCKstatementortheFORUPDATEclause,whileREADisonlyforquerypurpose.TheADMINandDELEGATEoptionsforcode-basedaccesscontrol:YoucannowprotectyourPL/SQLprogramsbygrantingrolestotheprogramunitsandnottotheusers.YoucangranttheroleswiththeADMINorDELEGATEoptiontoaprogramunit.WiththeDELEGATEoption,thegranteeisnotallowedtogranttheroletotheotherprograms.

OracleDatabase12cDataRedactionOracleDatabase12cDataRedactionpreventstheexposureofsensitivedatatothenon-authorizedusers.Thebeautyofthisfeatureliesinthefactthatitenablesdynamicmasking,whichmeansthatthedataisneverchangedonthestorageorcachebutgetsredactedatruntimejustbeforeitisdisplayedtotheuser.Thesecuritypoliciesarecreatedinthedatabaseandareconsistentlyactivetohidesensitiveinformationwheneverrequestedbytheapplications.Inaddition,thisfeaturehasnoimpactontheintegrityconstraintsanddatabaseoperationssuchasthebackup,restore,export,import,grid,andclusteroperations.

NoteTheOracleDatabase12cDataRedactionfeaturehasbeenbackportedtoOracleDatabase11.2.0.4.

AtypicalusecaseofDataRedactionwouldbearead-onlyapplicationthatfetchesthedatafromaproductionwarehouse.Similarly,theredactionpoliciescanbecreatedforacallcenterapplication.Therewillbemanysuchcaseswheredataviewisbasedontheuserauthorization.

DataRedactionexemptionsandmiscellaneousfeaturesDataRedactionisapartoftheAdvancedSecurityoption,whichcanbepurchasedwithOracleDatabaseEnterpriseEdition.ThefollowingarethesalientfeaturesofDataRedaction:

TheSYSandSYSTEMusersarealwaysexemptfromtheredactionpolicies.Thevirtualcolumnscannotberedacted.Theeditioningviewscannotberedacted.UserswiththeEXEMPTREDACTIONPOLICYsystemprivilegeareexemptfromtheredactionpolicies.YoucannotperformtheCTAS(CREATETABLEASSELECT)operationonaredactedtable.AredactionpolicycanbecontrolledusingtheDBMS_REDACTpackage.AusermusthavetheEXECUTEprivilegeonthepackage.

DataRedactionpoliciescanbecreatedfromEnterpriseManagerCloudControl12c.

DataRedactionfunctiontypesDataRedactioncanusethefollowingmethodsofredaction:

Fullredaction:Fullredactionreferstothecompletereplacementofacolumnvalue.Anumbertypevaluewillbereplacedwithzerooradummydatecanreplaceadate.Forexample,15/01/2015(andallthedatevalues)canberedactedas01/01/00.Partialredaction:Partialredactionreferstothemaskingofaportionofacolumnvalue.Forexample,thefirstfewdigitsoftelephonenumbersorsocialsecuritynumbersarereplacedwithX.Themaskingformatshownintheprecedingfiguredepictspartialredaction.Regularexpressions:Youcanuseregularexpressionstomaskthedatabasedonapatternandnotonthebasisofafixedlengthofthecharacters.Forexample,emailaddressesorcreditcardnumberscanbemaskedbasedonthepositionofthespecialcharacter.Randomredaction:Youcandirecttheredactionpolicytogeneratearandomvaluewithamatchingdatatypeforthecolumncarryingthesensitivedata.Noredaction:Thisisusedfortestingpurposesandcanbeusedbeforedeployingthesecuritypoliciesduringproduction.

DemonstrationLet’scontinuethecasestudyfromtheVirtualPrivateDatabasedemonstration.NotethatEMPisaVirtualPrivateDatabaseprotectedtable.WithDataRedaction,theobjectivewillbetomaskthevaluesfromtheSALandCOMMcolumnsoftheEMPtablefortheCLERK,MGR,andSALESusers.

ThefollowingPL/SQLblockcreatesaredactionpolicyontheSALcolumnoftheEMPtable.Astheredactionisfortheaccessfromthreeusers,thatis,SALES,MGR,andCLERK,thepredicateexpressionusingtheSYS_CONTEXTfunctionhasbeenincluded.

CONNECTsys/oracleASSYSDBA

/*GrantexecuteprivilegeonDBMS_REDACTtoscott*/

GRANTEXECUTEONsys.dbms_redactTOSCOTT

/

CONNECTscott/tiger

BEGIN

/*AddapolicytoredactSALcolumn*/

DBMS_REDACT.add_policy(


object_name=>'EMP',

column_name=>'SAL',

policy_name=>'redact_employee_info',

function_type=>DBMS_REDACT.full,

expression=>q'|sys_context('userenv','current_user')IN

('SALES','MGR','CLERK')|'

);

END;

/

Let’sverifytheimpactoftheredactionpolicy.TheSALcolumnisfullyredactedbyreplacingtheoriginalcolumnvaluesbyadefaultvalue,zero.NotethattheVirtualPrivateDatabasepolicyisstillactiveandenforced:

CONNmgr/mgr

SELECTempno,ename,job,sal,deptno

FROMscott.emp

/

EMPNOENAMEJOBSALDEPTNO

------------------------------------------------

7566JONESMANAGER020

7698BLAKEMANAGER030

7782CLARKMANAGER010

NoteForafullredactionpolicytype,thedefaultvaluesforthecolumnsarepickedupfromtheREDACTION_VALUES_FOR_TYPE_FULLdictionaryview.

YoucanalteraredactionpolicyusingtheALTER_POLICYprocedurefromtheDBMS_REDACTpackage.TheACTIONattributeisusedtorecordthechangesthatyoumakewhilealteringthepolicy.

Let’saltertheredactionpolicyandmasktheHIREDATEcolumnvalue.Thistime,wewillusethepartialredactiontechniquetomaskthedatevalue.

CONNECTscott/tiger

BEGIN

/*AlterpolicytoincludeHIREDATEcolumn*/

DBMS_REDACT.alter_policy(


object_name=>'EMP',


action=>DBMS_REDACT.add_column,

column_name=>'hiredate',

function_type=>DBMS_REDACT.partial,

function_parameters=>'m1d1y1900'

);

END;

/

Now,let’sconnecttotheSALESuserandcheckthemaskedvaluesoftheHIREDATEcolumn:

CONNsales/sales

SELECTempno,ename,job,sal,hiredate

FROMscott.emp

/

EMPNOENAMEJOBSALHIREDATE

------------------------------------------------

7499ALLENSALESMAN001-JAN-00

7521WARDSALESMAN001-JAN-00

7654MARTINSALESMAN001-JAN-00

7844TURNERSALESMAN001-JAN-00

Let’smaskanothercolumntodemonstratetheredactionusingregularexpression.We’llaltertheEMPtabletoaddtheEMAILcolumn:

CONNECTscott/tiger

ALTERTABLEemp

ADD(emailVARCHAR2(30))

/

UPDATEemp

SETemail=LOWER(ename)||'@xyz.com'

/

COMMIT

/

ThefollowingPL/SQLblockmaskstheEMAILcolumnusingaregularexpression:

BEGIN

/*AlterpolicytoincludeEMAILcolumn*/

DBMS_REDACT.alter_policy(


object_name=>'EMP',


action=>DBMS_REDACT.add_column,

column_name=>'email',

function_type=>dbms_redact.regexp,

regexp_pattern=>dbms_redact.RE_PATTERN_EMAIL_ADDRESS,

regexp_replace_string=>dbms_redact.RE_REDACT_EMAIL_NAME

);

END;

/

TheprecedingpolicyincludestheEMAILcolumnandmasksitusingaregularexpression.Notetheregularexpressionpatternandreplacethestringconstants.TheDBMS_REDACTpackageincludesalistofthestandardsecurityconstructsthatcanbereadilyusedwhilecreatingtheredactionpolicy.Let’sconnecttoCLERKuserandchecktheemailcolumn:

CONNclerk/clerk

SELECTempno,ename,job,sal,hiredate,email

FROMscott.emp

/

EMPNOENAMEJOBSALHIREDATEEMAIL

--------------------------------------------------------

[email protected]

[email protected]

[email protected]

[email protected]

TheDataRedactionmetadataYoucanquerythefollowingdictionaryviewstofindthemetadatainformationabouttheredactionpolicies:

REDACTION_POLICIES:ThisviewstorestheredactionpolicydetailsREDACTION_COLUMNS:Thisviewstoresthedetailsofredactedcolumnsinthedatabase

Thefollowingtwoqueriesdisplaytheredactionpolicydetailsthatwerecreatedintheprecedingdemonstration:

CONNECTsys/oracleASSYSDBA

SELECTpolicy_name,expression

fromREDACTION_POLICIES

/

POLICY_NAMEEXPRESSION

----------------------------------------------------------------

redact_employee_infosys_context('userenv','current_user')IN

('SALES','MGR','CLERK')

SELECTobject_name,column_name,function_type,function_parameters

FROMredaction_columns

/

OBJECT_NAMECOLUMN_NAMEFUNCTION_TYPEFUNCTION_PARAMETERS

--------------------------------------------------------------

EMPHIREDATEPARTIALREDACTIONm1d1y1900

EMPSALFULLREDACTION

EMP EMAILREGEXPREDACTION

SummaryInthischapter,wecoveredthefundamentalsofdatabasesecuritysolutionsfromOracle.AfteranoverviewoftheOracleDatabaseSecuritysolution,wedivedintothefine-grainedaccesscontrolandVirtualPrivateDatabase.TheVirtualPrivateDatabaseenforcesrow-levelsecuritythroughthepoliciesandrestrictsthedataaccessforunauthorizedusers.Dependingonauser’sidentityandrole,theapplicationcansetupmultitenancyandensureuserisolationaswell.

OracleDatabase12cmadeconsiderableenhancementstoitssecurityoffering.Thesummaryoftheseenhancementswasincluded,whiletheDataRedactionfeaturewascoveredindetailalongwithdemonstrations.Inthenextchapter,wewilldiveintoanotherkeyareathathascontinuouslygainedmoreweightwithtime:handlingoflargeobjectsintheOracleDatabase.WewillbefocusingthemajorityofourdiscussionaroundSecureFilesanditsoptimizations.

PracticeexerciseIdentifythecorrectstatementsabouttheworkingofFineGrainedAccessControl.

1. Atablecanhaveonlyonesecuritypolicy.2. DifferentpoliciescanbeusedtoprotecttheSELECT,INSERT,UPDATE,and

DELETEstatementsonatable,butnotone.3. ThepolicyfunctionreturnsthepredicateinformationasWHERE<Column>=

<Value>.4. Onceassociated,theFGACpolicycannotberevokedfromthetable.

AsecuritypolicycanbeassociatedtoagroupofobjectsbytheDBA.Statewhetherthisistrueorfalse.

1. True2. False

ChoosethecorrectstatementaboutDBMS_RLS.

1. DBMS_RLSisusedonlyforrow-levelsecuritypolicies.2. ThepackageisownedbySYS.3. Itcancreate/drop/refreshpoliciesandcreate/droppolicygroups.4. UsingDBMS_RLStosetthepolicydegradestheapplicationperformance.

Identifythecorrectstatementsaboutthecontextofanapplication.

1. AuserwhoholdstheCREATECONTEXTprivilegecancreateacontext.2. ItisownedbytheSYSuser.3. AusercancheckthecontextmetadatainUSER_CONTEXTS.4. Thetrustedpackageassociatedwiththecontextmustexistbeforethecontextis

created.

ArrangethesequenceoftheVirtualPrivateDatabaseimplementationusingapplicationcontexts.

i.Creatingpolicyfunction.

ii.Creatingtrustedpackage.

iii.Creatingandsettingapplicationcontexts.

iv.AssociatingapolicyusingDBMS_RLS.

1. iii,ii,i,iv2. ii,iii,iv,i3. iii,iv,i,ii4. iv,i,ii,iii

Allthepoliciesondifferentcolumnsofthesametablearecollectivelyknownaspolicygroups.

1. True2. False

Identifythecorrectstatementsaboutthepolicytypes.

1. Sharedstaticpolicyisanextensiontothestaticpolicieswheremultiplestaticpoliciescanbesharedamongmultipleusers.

2. Sharedstaticpolicyisanextensiontothestaticpolicieswhereasinglestaticpolicycanbesharedamongmultipleobjects.

3. STATICisthedefaultpolicytype.4. DYNAMICisthedefaultpolicytype.

Pickthecorrectstatementabouttheapplicationcontexts.

1. OnlyaDBAcancreateacustomapplicationcontextandaddattributesunderit.2. TheDBAcanmodifyallUSERENVattributes.3. Thepackageusedforthecontextcreationmayormaynotexistintheschema.4. Globalcontextscanbeusedbyalltheusersonaserver.

ApolicyoftheCONTEXT_SENSITIVEtypeexecutesthepolicyfunctiononce,everytimethequeryisreparsed,ifthelocalcontexthasbeenchanged.

1. True2. False

Identifythecauseofthefollowingexception:

SQL>SELECT*FROMemployees;

select*fromemployees

*

ERRORatline1:

ORA-28110:policyfunctionorpackageORADEV.F_JOB_POLICYhaserror

1. ThepolicyfunctionF_JOB_POLICYdoesnotexist.2. ThepolicyfunctionF_JOB_POLICYhasnotbeenspecifiedin

DBMS_RLS.ADD_POLICYtoaddthepolicyontheemployeestable.3. Thepredicatereturnedbythepolicyfunctionisnotappropriateforthisquery.4. TheVirtualPrivateDatabasepolicyontheemployeestableisinvalidandhas

errors.

Chapter7.OracleSecureFilesThefactthatdataisgrowingmultifoldsatatremendousspeedhasledtotheevolutionofanumberofdatamanagementtrendsandBigDataisoneofthem.Alargeamountofinformationfromwebcontent,sensors,documents,images,andlocationserviceshaspushedorganizationstoplaceseriousthoughttodatamanagementstrategiesanddistiloutnuggetsofinformation.Thedatacanbestructured,semi-structured,orunstructured.

Inrelationaldatabaseterminology,unstructureddatasuchasbinaryfilesordocumentsareclassifiedaslargeobjects.Oraclehasbeenallowinguserstostorelargeobjectsinthetablesofarelationaldatabaseforalongtime.WhilethelargeobjectsareprototypedasBLOBorCLOBinatable,thereisaprovisiontostoreXMLdocuments,spatialdataandtextusingdedicateddatatypes.Inthischapter,wewillfocusonlargeobjecthandlingintheOracleDatabase.YouwillunderstandhowlargeobjectsorLOBsarestoredinthedatabase,whattheoptimizationfeaturesare,andhowithasevolvedovertime.TheOracleDatabase11gintroducedanewformatoftheLOBstorageknownasSecureFiles.SecureFilesofferoptimizedstorageandenableabetterperformanceofthelargeobjectsinanOracledatabase.

Thechapterisoutlinedasfollows:

IntroductiontoLargeObjectsClassificationofLargeObjectsWorkingwithLOBdatatypes

CreatingLOBdatatypesManagingLOBdatatypesMigratingLONGtoLOB

OracleSecureFiles

AnoverviewWorkingwithSecurefilesMigratingBasicFilestoSecureFiles

OracleDatabase12cSecureFilesenhancements

IntroductiontoLargeObjectsAsthenamesuggests,largeobjectsorLOBsrefertolargedata.Acolumnofalargeobjecttypeinatablecanstoresemi-structuredorunstructureddata.Semi-structureddatacanbeacharacter-baseddocumentthatcanbeprocessedinanearrelationalformat.Unstructureddataisabinaryfilethatisdifficulttointerpretlogically.Forexample,anXMLfileisasemi-structureddocumentwhileanimageoragraphicsfileisanunstructuredformatofthedata.

OracleDatabasesupportsthestorageoflargeobjectsalongthefollowingaspects:

Storage:Justlikeanyotherdata,theOracleDatabaseallowsthestorageoflargeobjectsincolumnswithinatable.ThecolumnsofLOBdatatypescanefficientlystoreasemiorunstructureddataobject,compressitandevenencryptitinthedatabase.TheLOBdatatypestoredintheOracleDatabaseabidesbytheACID(Atomicity,Consistency,Isolation,andDurability)properties.Oracleprovidesawiderangeofadministrativecontrolstomanageandmaintainlargeobjectsinthedatabase.Access:OracleSecureFiles(discussedlaterinthischapter)providesyouwithhighlyoptimizedaccessoflargeobjectsfromtheOracleDatabase.SecureFiles,introducedinOracleDatabase11gandthedefaultLOBstorageoptioninOracleDatabase12c,acceleratesLOBperformancethroughvectoroptimizationtechniques.Forsemi-structureddatatypessuchasOracleTextorOracleSpatial,Oracleenablesindexingtechniquestoimprovequeryperformance.Security:TheLOBdatatypeintheOracleDatabasestaysprotectedandsecure.Fine-graineddataaccesssecuritypoliciesapplytolargeobjectsaswell.

TheuseoftheLONGandLONGRAWdatatypeswassucceededbytheLOBdatatypesinOracle8i.AlthoughLONGandLONGRAWarestillsupported,OraclerecommendstheusageoftheLOBdatatypesinplaceofLONGandLONGRAWduetothefollowingreasons:

AtablecanhaveonlyoneLONGorLONGRAWcolumnALONGorLONGRAWcolumncanstoredataonlyupto2GBTheLONGdatacanonlybeaccessedsequentially

ItisrecommendedforlegacyapplicationsusingLONGorLONGRAW,tomigratetoLOBssoastoleveragethebenefitsofstorageoptimizationandenhancedperformance.

ClassificationofLargeObjectdatatypesALOBdatatypecanbeclassifiedonthebasisofitsstorageproperties.ThefollowingfigurebranchesoutthedifferentLOBtypesinOracle:

InternalLOBAninternalLOBcanbestoredinandaccessedfromthedatabase.AcolumnofBLOB,CLOB,orNCLOBcanbeincludedinatabletostorelargeobjects,likeallothercolumns.NotethattheinternalLOBdatatypescanbeusedinPL/SQLaswell.

PersistentandTemporaryLOB

ALOBdatatypeispersistentifitisphysicallystoredinthedatabasetables.Aswithallothercolumnvalues,itcanbeapartofadatabasetransaction.

AtemporaryLOBisusedtoinstantiateaLOBinaPL/SQLprogram.ItisusedtoperformtheLOBoperations,whicharecarriedoutinatemporarytablespace.IfthetemporaryLOBvalueisinsertedintoadatabasetable,theLOBinstancebecomespersistent.

ExternalLOBIftheLOBdatadoesnotresideinsidetheOracleDatabase,itisanExternalLOB.AcolumnofanexternalLOBdatatype,BFILE,storesonlytheLOBlocatorandnotthedata.Thedataresidesoutsidethedatabasestorageasanoperatingsystemfileontheserverhost.TheintegrityanddurabilityofexternalLOBsmustbelayeredattheoperatingsystemlevel.

NoteBFILEisaread-onlydatatypeanddoesnotparticipateindatabasetransactions.

LOBrestrictionsALOBisaspecialfeaturethatallowsadatabasemanagementsystemtostoreunstructureddatasuchasfilesanddocuments.However,therearecertainrestrictionsontheusageofaLOBanditsrelatedoperations,listedasfollows:

ALOBcolumncannotbeaprimarykeyofatableALOBcolumncannotbeusedintheORDERBYclauseofSELECTqueryALOBcolumncannotappearintheGROUPBYclauseofaSELECTqueryALOBcolumncannotbeusedtojointwotablesYoucannotusetheDISTINCTclausewithaLOBcolumninaSELECTqueryALOBcolumncannotbeselectedinaUNIONqueryAB-TreeindexorabitmapindexcannotbecreatedonaLOBcolumn

LOBdatatypesinOracleOracleprovidesfourdatatypesdedicatedfordeclaringlargeobjects,namely:BLOB,CLOB,NCLOB,andBFILE.

BLOBandCLOBTherearethreetypesofinternalLOBdatatypes,namely:

BLOB:TheBinaryLargeObjectdatatypeisusedtostorelargebinaryfilesthatcannotbelogicallybrokendowntodatabitssuchasPDFs,images,audiosorvideos,andsoon.CLOB:TheCharacterLargeObjectdatatypestoresthesingle-bytecharacterdatainthedatabasecharactersetformat.Itsupportsfixed-widthcharacterformats.NCLOB:TheCLOBdatatypethatcanstorenationalcharactersetdataandsupportvaryingwidthformatcharactersets.

NoteStartingfromOracle10g,OraclecancasttheCLOBdatatotheVARCHAR2dataimplicitly.

BFILEABFILEisanSQLdatatypefortheexternalLOBdatatype.Itistheread-onlydatatypethatstoresalocatorforabinaryfilewhosephysicallocationisoutsidetheOracleDatabase.DeletingaBFILEcolumnvalue(orsettingittoNULL)willdropthereferencepointertotheexternalfilebutwillnotdeletethefile.

TipThesecurityandintegrityoftheexternallylocatedfilemustbemanagedandadvisedattheoperatingsystemlevel.Oraclerecommendstheusageofdatabasedirectoriesinordertosecuretheuseractionstothefilelocation.Asession-levelinitializationparameterSESSION_MAX_OPEN_FILESdeterminesthemaximumnumberofBFILEsthatcanbeopenedinasession.Thedefaultparametervalueis10butthiscanbemodifiedusingtheALTERSESSIONcommand.Ifyouwanttoclosealltheopenfiles,youcandosobycallingDBMS_LOB.FILECLOSEALL.

SomemorerelatedstuffWhileworkingwiththeLOBdatatypes,youmustbefamiliarwithafewmoretermssuchastheLOBinstance,LOBinitialization,andtheDBMS_LOBpackage.AthoroughunderstandingisessentialtoperformtheLOBoperations.

TheLOBlocatorStructurally,aLOBinstanceismadeupofaLOBlocatorandvalue.TheLOBlocatorstoresthepointertotheLOBvaluewhiletheLOBvaluestorestheactualphysicaldata.

BeitaninternalorexternalLOB,thecolumninthetableholdsjustthelocator.InthecaseofBLOB,CLOB,andNCLOB,theLOBlocatorisusedtoretrievethevaluefromtheLOBinstance.ForBFILE,thelocatorisusedtoretrievetheexternallylocatedoperatingsystemfile.

LOBinstanceinitializationThestateofaLOBcolumncanbeNULL,empty,orpopulated.ALOBinstancewithoutalocatorisaNULLLOBandcannotbepassedasanargumenttoaprogram.ToallowaLOBtobepassedasaparametertoaprogram,itmustbeinitialized.YoucaninitializeaLOBinstanceofapersistentLOBcolumnusingtheOracle-suppliedconstructorfunctions,EMPTY_BLOB()andEMPTY_CLOB()forBLOBandCLOBrespectively.ThefunctionsinitializetheLOBsbutdonotpopulatethemwithanydata.Thesefunctionscanbeusedinthefollowingscenarios:

TheLOBcolumndefaultcanbesettooneoftheconstructorfunctionsinaCREATETABLEstatement:

CREATETABLEt_LOB_init

(idNUMBER,

b_LOBBLOBDEFAULTEMPTY_BLOB(),

c_LOBCLOBDEFAULTEMPTY_CLOB()

)

/

Similarly,thecolumndefaultcanbesetwhileaddingacolumnusingtheALTERTABLEcommand.

AnemptyLOBinstancecanbeinsertedintotheLOBcolumninanINSERTstatement.Forexample,thefollowingINSERTstatementusestheEMPTY_BLOB()functionortheemptylocatorinsteadofaprofileimage:

/*Inserttestdataintheabovetable*/

INSERTINTOt_LOB_init(ID,B_LOB,C_LOB)

VALUES

(129,EMPTY_BLOB(),EMPTY_CLOB())

/

TheLOBvariablesinaPL/SQLblockcanbeinitializedeitherinthedeclarativesectionorprogrambody:


DECLARE

/*DeclarelocalLOBvariables*/

l_my_cLOBCLOB:=EMPTY_CLOB();

l_my_bLOBBLOB:=EMPTY_BLOB();

BEGIN

...

--executablesection

...

END;

/


YoucaninitializeaBFILEcolumnusingtheBFILENAMEfunction.TheBFILENAMEfunctionacceptsthedatabasedirectoryandfileasinputsandreturnsaBFILElocator.ABFILElocatorisareferencetothefilelocatedexternallyintheoperatingsystem.ThesyntaxoftheBFILENAMEfunctionisasfollows:

FUNCTIONBFILENAME(directoryINVARCHAR2,filenameINVARCHAR2)

RETURNBFILE;

TheBFILENAMEfunctionisalsousedwhilepopulatingaLOBinstancefromanexternalfileinaPL/SQLblock.

TheDBMS_LOBpackageOracleprovidesabuilt-inpackage,DBMS_LOB,thatallowsuserstoperformtransactionaloperationsontheinternalLOBsandreadoperationsforBFILEs.ThepackageisownedbySYS.AuserwiththeEXECUTEprivilegeontheDBMS_LOBpackagecaninvokeitssubprograms.

NoteForthefollowingsubsections,refertotheOracleDatabaseOnlineDocumentation12cRelease1(12.1)/DatabaseAdministrationathttps://docs.oracle.com/database/121/ARPLS/d_LOB.htm.


TheDBMS_LOBpackageconstantshavebeenconsolidatedinthefollowingtable:

Constant Description Value


FILE_READONLY OpenBFILEinread-only 0

LOB_READONLY Read-onlyLOB 0

LOB_READWRITE ReadwriteLOB 1

LOBMAXSIZE MaximumsizeofLOB 18446744073709551615

https://docs.oracle.com/database/121/ARPLS/d_LOB.htm

SESSION CreatetemporaryLOBforthedurationofasession 10

CALL CreatetemporaryLOBforthedurationofatransaction 12

TheDBMS_LOBoptiontypes

OPT_COMPRESS SecureFilecompressionoption 1

OPT_ENCRYPT SecureFileencryptionoption 2

OPT_DEDUPLICATE SecureFilededuplicateoption 4

TheDBMS_LOBoptionvalues

COMPRESS_OFF SecureFilecompressionOFF 0

COMPRESS_ON SecureFilecompressionON 1

ENCRYPT_OFF SecureFileencryptionOFF 0

ENCRYPT_ON SecureFileencryptionON 2

DEDUPLICATE_OFF SecureFilededuplicationOFF 0

DEDUPLICATE_ON SecureFilededuplicationON 4

TheDBFSstatevaluetypes

DBFS_LINK_NEVER Non-archivedLOB 0

DBFS_LINK_NO LOBarchivedbutreadbythedatabase 2

DBFS_LINK_YES LOBarchived 1

TheDBFSCacheFlags

DBFS_LINK_CACHE ArchiveandcachetheLOBdata 1

DBFS_LINK_NOCACHE ArchivetheLOBdatawithoutcachingitinthedatabase 0

TheDBMS_LOBdatatypes

TheDBMS_LOBpackageworkswiththefollowingdatatypes:

Datatype Description

BLOB SourceordestinationbinaryLOB

RAW SourceordestinationRAWbuffer(usedwithBLOB)

CLOB SourceordestinationcharacterLOB(includingNCLOB)

VARCHAR2 Sourceordestinationcharacterbuffer(usedwithCLOBandNCLOB)

INTEGER SpecifiesthesizeofabufferofaLOB

BFILE Large,binaryobjectstoredoutsidethedatabase

TheDBMS_LOBsubprograms

TheDBMS_LOBsubprogramsarelistedinthefollowingtable:

Subprogram Type Description

APPEND Procedure AppendsthecontentsoftheLOBsourcetotheLOBdestination

CLOSE Procedure ClosesapreviouslyopenedinternalorexternalLOB

COMPARE Function ComparestwoentireLOBsorpartsoftwoLOBs

CONVERTTOBLOB ProcedureReadsthecharacterdatafromasourceCLOBorNCLOBinstance,convertsthecharacterdatatothespecifiedcharacter,writestheconverteddatatoadestinationBLOBinstanceinbinaryformat,andreturnsthenewoffsets

CONVERTTOCLOB ProcedureTakesasourceBLOBinstance,convertsthebinarydatainthesourceinstancetothecharacterdatausingthespecifiedcharacter,writesthecharacterdatatoadestinationCLOBorNCLOBinstance,andreturnsthenewoffsets

COPY Procedure Copiesall,orapart,oftheLOBsourcetotheLOBdestination

CREATETEMPORARY Procedure CreatesatemporaryBLOBorCLOBanditscorrespondingindexintheuser’sdefaulttemporarytablespace

ERASE Procedure Erasestheentire,orapart,ofaLOB

FILECLOSE Procedure Closesthefile

FILECLOSEALL Procedure Closesallpreviouslyopenedfiles

FILEEXISTS Function Checksifthefileexistsontheserver

FILEGETNAME Procedure Getsthedirectoryobjectnameandfilename

FILEISOPEN Function ChecksifthefilewasopenedusingtheinputBFILElocators

FILEOPEN Procedure OpensaBFILE

FRAGMENT_DELETE Procedure DeletesthedataatthegivenoffsetforthegivenlengthfromtheLOB

FRAGMENT_INSERT Procedure Insertsthegivendata(limitedto32KB)intotheLOBatthegivenoffset

FRAGMENT_MOVE Procedure Movesachunkofbytes(BLOB)orcharacters(CLOB/NCLOB)fromthegivenoffsettothenewoffsetspecified

FRAGMENT_REPLACE Procedure Replacesthedataatthegivenoffsetwiththegivendata(nottoexceed32KB)

FREETEMPORARY Procedure FreesthetemporaryBLOBorCLOBinthedefaulttemporarytablespace

GETCHUNKSIZE Function ReturnstheamountofspaceusedinLOBCHUNKtostoretheLOBvalue

GETLENGTH Function GetsthelengthoftheLOBvalue

GETOPTIONS Function Obtainssettingscorrespondingtotheoption_typesfieldforaparticularLOB

GET_STORAGE_LIMIT Function ReturnsthestoragelimitforLOBsinyourdatabaseconfiguration

INSTR Function ReturnsthematchingpositionofthenthoccurrenceofthepatternintheLOB

ISOPEN Function CheckstoseeiftheLOBwasalreadyopenedusingtheinputlocator

ISTEMPORARY Function ChecksifthelocatorispointingtoatemporaryLOB

LOADBLOBFROMFILE Procedure LoadstheBFILEdataintoaninternalBLOB

LOADCLOBFROMFILE Procedure LoadstheBFILEdataintoaninternalCLOB

LOADFROMFILE Procedure LoadstheBFILEdataintoaninternalLOB

OPEN Procedure OpensaLOB(internal,external,ortemporary)intheindicatedmode

READ Procedure ReadsthedatafromtheLOBstartingatthespecifiedoffset

SETOPTIONS Procedure EnablesCSCEfeaturesonaper-LOBbasis,overridingthedefaultLOBcolumnsettings

SUBSTR Function ReturnspartoftheLOBvaluestartingatthespecifiedoffset

TRIM Procedure TrimstheLOBvaluetothespecifiedshortlength

WRITE Procedure WritesthedatatoaLOBfromagivenoffset

WRITEAPPEND Procedure WritesabufferattheendofaLOB

LOBusagenotesAsadatabaseadministrator,youwillfindthefollowingnotesusefulwhileworkingwithLOBsinadatabaseapplication:

ObjecttypescanhavetheLOBtypeattributes.YoucanchangethetablespaceofaLOBsegmentbyusingtheALTERTABLE…MODIFYcommand.LOBsarestoredinlinealongwiththetablerowiftheLOBsizeislessthanorequalto4000bytes.YoucanspecifyENABLE|DISABLESTORAGEINROWintheLOBstorageclauseforinlineandout-of-linestorage.However,theLOBlocatorsarealwaysstoredintheLOBcolumnofthetable.NoLOBstoragespecificationsareapplicabletotheBFILEcolumns.

OracleSecureFilesOracleSecureFileswereintroducedinOracleDatabase11gRelease2toenableoptimizedstorageoflargeobjectsandenhancedperformance.SecureFilesarere-engineeredLOBstoragearchitecturethatisdesignedtoleveragethejointcapabilitiesofanOracleDatabaseandafilesystem.OracleSecureFilesgreatlybenefittedfromthefilesystem-likefeaturessuchasdeduplication,compression,andencryption.Inaddition,theSecureFilesdataworkswithtrusteddatabasefeaturessuchasflashback,fine-grainedauditing,RealApplicationClusters,AutomaticStorageManagement,andInformationLifecycleManagement.TheoptimizationfeaturesinSecureFilesarededuplication,compression,andencryption.

WiththeintroductionofOracleSecurefiles,theolderLOB,thatis,allLOBsuntilOracleDatabase11gRelease1,willbeknownasBasicFiles.

DeduplicationandcompressionLetusfirstunderstandwhatoptimizestheSecureFilesstorageonthedisk.OracleSecureFilesgivesthebestperformanceduringthewriteoperationsduetothebulkallocationofcontiguousblocksonthedisk.TheSecureFilesegmentsmustresideonanAutomaticSegmentSpaceManagement(ASSM)managedtablespace.

Inaddition,advancedfeaturessuchasdeduplicationandcompressioncontributelargelytotheLOBstorageoptimizationbyreducingtheoverallsizeofdatagettingwrittentothestorage.TheOracleDatabasemaintainsaninternalindexofprefixhashandfullhashforalltheobjects.Duringthewriteoperations,theprefixhashisgeneratedfortheobject,whichisthenmatchedagainsttheprefixhashesavailableintheinternalindex.Iftheprefixhashisnotmatched,theobjectiswrittentothedisk,otherwisetheobjecthashcomparisonisperformed.Amismatchduringfullhashcomparisonwillagainresultinanobjectwrite.Iftheobjecthashesarematched,thenapointer(memoryvector)tothemasterhashiswrittentotheLOBcolumnforthecurrentwriteoperation.Thus,forduplicateobjects,theOracleDatabasestoresasinglemastercopy.YoucanuseDEDUPLICATEorKEEP_DUPLICATEStoenableordisablethededuplicatefeature.

Withregularchecksonthesizeandaccess,theOracleDatabasecancompresstheSecureFiles,whichmaximizestheirspaceutilization.YoucanspecifythecompressionlevelasCOMPRESSLOW,COMPRESSMEDIUM(default)orCOMPRESSHIGHdependingontheSecureFileaccessrateandavailableCPUcycles.Tocompletelydisablethecompression,specifyNOCOMPRESSintheSecureFileLOBstoragespecification.NotethattheLOBcompressionisdifferentfromthetablecompression.

ThededuplicationandcompressionfeaturestransparentlyaccountfortheenhancedperformanceofSecureFiles.Thededuplicationandcompressionfeaturescanbespecifiedatthetableaswellasthepartitionlevel.

EncryptionASecureFileLOBcolumncanbesafelyandtransparentlyencryptedordecryptedusingtheTransparentDataEncryption(TDE)featureofOracle.YoucanusetheENCRYPTorDECRYPTclausetoenableordisabletheencryptionfeature.

IfyouenableallthreeadvancedfeaturesforaSecureFile,theOracleDatabasewillfirstdeduplicate,thencompress,andfinallyencryptit.

OracleSecureFilecompressionanddeduplicationarepartoftheOracleAdvancedCompressionoptionOracleSecureFileencryptionispartoftheOracleAdvancedSecurityoption

FileSystemLoggingYoucanalsoenableafilesystem-likeloggingforOracleSecureFilestoreduceredogenerationwhileloadingtheLOBdataintoatable.Typically,OracleDatabaselogsthedatachangesaswellasmetadatachangesintheredologs.Ontheotherhand,atypicalfilesystemsimplytracksthemetadatachanges.TheOracleSecureFilelogginglevelcanbesettoFILESYSTEM_LIKE_LOGGINGinordertoenabletheloggingofonlytheLOBmetadata.InthecaseoflargesizeSecureFiles,thefilesystem-likeloggingcutsshorttheredogenerationbyahugemarginandimprovesthedataloadingperformance.ThedefaultloggingmodeforSecureFilesisNOCACHELOGGING.

WriteGatherCacheWriteGatherCache(WGC)isachunkofmemoryallocatedwithinthebuffercacheforstaginglargeLOBwriteoperations.Themaximumsizeofthecachecanbe4MegaBytes(MB).WhenmultipleconcurrentserverprocessesattempttowritetheLOBdatatothestoragelayer,theWGCfacilitatesthebufferingoflargewriteI/Os,whichhelpsintheallocationoflargeadjacentspaceallocation.ItisrecommendedtoavoidfrequentCOMMIToperationsastheywillflushthiscache.TheSecureFilededuplicationcheckisperformedwhilethedataisinWriteGatherCache.TheusageofWriteGatherCachegreatlyimprovesthewriteperformanceoftheSecureFiles.

FreespacemanagementThefreespacemanagementkeepstrackoftheallocationanddeallocationoftheSecureFileLOBsintheLOBsegments.AbackgroundfreespacemonitorkeepsacheckonthecurrentspaceusageoftheSecureFileLOBsintheLOBsegments.Itisthebackgroundfreespacemonitorthatdeterminestheallocationofextents.

Whilewritinginasegment,thefixedCHUNKparametervaluecanleadtothefragmentationofthelargeobjectdata.TheOracleSecureFilesusealargeranddynamicchunksizeinordertosupportthelargeallocationofcontiguousblocksondiskandavoidfragmentation.ThisfeaturegreatlyimprovesthewriteperformanceofSecureFiles.

OracleSecureFilesrequirenoindexessuchasb-tree.Inconcurrentenvironments,indexmaintenanceonthelargeobjectscanbeacostlyoperation.SecureFilesuseprivatemetadatablocksthatarecontiguouslylocatedintheLOBsegment.

UnlikeolderLOBs,SecureFilesdonotsufferfromhighwatermarkcontentionissuesbecausethefreedspaceisdeallocatedandreclaimedsimultaneously.

OracleSecureFilesallowaLOBtobeprefetchedfromtheOracleDatabasetoimprovereadperformance.TheprefetchintelligencecomesfromtheSecureFilesaccesspatternsthatincreasethroughputbyasignificantmargin.

BasicFilesandSecureFilesStartingfromOracleDatabase11g,aLOBdatacanbestoredeitherasaBasicFileorSecureFile.OraclerecommendsthatyouusetheSecureFileapproachforstoringlargeobjectsinthedatabasebecauseitoptimizesthestoragemechanismandboostsboththereadandwriteperformance.IfyourapplicationusesanASSMmanagedtablespace,youmustcreateaLOBasaSecureFile.

UntilOracle11g,thedefaultstoragetypewasBasicFile.However,withOracleDatabase12c,SecureFileisthedefaultstoragemechanism.Theapplicationsworkingwithanolderversionofthelargeobjects,thatis,BasicFilesareadvisedtomigratetoSecureFilesusingtheonlineredefinitionapproach.

Thedb_securefileparameterOracleDatabase11gintroducedanewinitializationparameterdb_securefiletocontrolthebehaviorofLOBstorageinthedatabase.UntilOracle11g,thedefaultvalueoftheparameterwasPERMITTED.StartingfromOracleDatabase12c,thedefaultvalueofthedb_securefileparameterisPREFERRED.TheparametercanbesetusingtheALTERSYSTEMorALTERSESSIONstatement.Theparametervaluesarebrieflydescribedasfollows:

PREFERRED:ThisisthedefaultparametervalueinOracleDatabase12corCOMPATIBLEsetto12.0.0.0andhigher.PERMITTED:ItallowsthecreationofLOBsasSecureFiles,iftheLOBstorageisspecifiedasSECUREFILE.ALWAYS:AlltheLOBsegmentsontheASSMmanagedtablespacesarecreatedasSecureFiles.NotethatLOBsonanon-ASSMtablespacewillstillbeBasicFiles.FORCE:AlltheLOBcolumnsonanASSMtablespacewillbeforciblycreatedasSecureFiles.Inaddition,noLOBcanbecreatedonanon-ASSMtablespace.NEVER:ItrestrictsthecreationofSecureFiles.IGNORE:ItignoresthecreationofSecureFiles.AlltheLOBcolumnsarecreatedasBasicFiles.

WorkingwithLOBsNowthatweknowthebenefitsofOracleSecureFiles,let’sillustratehowtoworkwiththeLOBdataintheOracleDatabase.Inourcasestudy,youwillseethecomparisonbetweenBasicFilesandSecureFiles.

Let’sfirstverifythesettingofthedb_securefileinitializationparameter:

connsys/oracleasSYSDBA

showparameterdb_securefile

NAMETYPEVALUE

----------------------------------

db_securefilstringPREFERRED

WewillusethedefaultsettingoftheparameterbecauseitallowsthecreationofaSecureFileontheASSMtablespaceandthebehaviorcanbeoverriddenbyexplicitlyspecifyingBasicFile.

Fortestingpurposes,let’screatetwotablespaceswithdifferentsegmentspacemanagement.TheTBS_BASICtablespaceisamanuallymanagedtablespacewhileTBS_SECUREisanASSMtablespace:


/*Createamanuallymanagedtablespace*/

CREATETABLESPACEtbs_basic

DATAFILE'/u01/app/oracle/oradata/orcl/tbs_basic.dbf'

SIZE200M

SEGMENTSPACEMANAGEMENTMANUAL

/

Tablespacecreated.

/*CreateatablespacewithASSM*/

CREATETABLESPACEtbs_secure

DATAFILE'/u01/app/oracle/oradata/orcl/tbs_secure.dbf'

SIZE200M

SEGMENTSPACEMANAGEMENTAUTO

/

Tablespacecreated.

/*Verifythesegmentspacemanagementoftablespaces*/

SELECTtablespace_name,segment_space_management

FROMdba_tablespaces

WHEREtablespace_namelike'TBS%'

/

TABLESPACE_NAMESEGMEN

---------------------------------

TBS_BASICMANUAL

TBS_SECUREAUTO

ThefollowingCREATETABLEscriptscreatetwotables:EMP_BASICandEMP_SECURE.BoththetablesincludeaBLOBcolumn:MISC_DOCS.IntheEMP_BASICtable,theMISC_DOCScolumnisstoredasaBasicFilewhileintheEMP_SECUREtable,thecolumnisstoredasaSecureFile.NotetheBASICFILEandSECUREFILEkeywordspecificationtodifferentiatethetwostorageapproaches.TheLOBsegmentswillbecreatedontheprecedingtablespacesaswell:

connscott/tiger

/*CreateatableEMP_BASIC*/

CREATETABLEemp_basic

(empno,ename,deptno,job,sal,misc_docs)

LOB(misc_docs)

STOREASBASICFILE

(tablespaceTBS_BASIC)

AS

SELECTempno,ename,deptno,job,sal,empty_bLOB()

FROMemp

/

/*CreateatableEMP_SECURE*/

CREATETABLEemp_secure

(empno,ename,deptno,job,sal,misc_docs)

LOB(misc_docs)

STOREASSECUREFILE

(tablespaceTBS_SECURE)

AS

SELECTempno,ename,deptno,job,sal,empty_bLOB()

FROMemp

/

LOBmetadataTheUSER_LOBSdictionaryviewincludesaSECUREFILEcolumntoidentifyacolumnasSecureFileorBasicFileinatable.ForeachLOBtypecolumninatable,OraclecreatesaLOBsegmentseparatelyfromthetablesegment.Implicitly,OraclealsocreatesaninternalindexstructurefortheLOBcolumnonthesametablespacespecifiedforLOB.NotethattheLOBindexstructuredoesnotneedtoberebuiltormaintained.

ThefollowingSQLstatementqueriestheUSER_LOBSdictionaryviewandliststheLOBsegment,tablespace,in-rowattribute,andSecureFilecharacteristicoftheLOBcolumns:

connscott/tiger

/*QueryUSER_LOBSforLOBmetadata*/

WITHCAS

(

SELECTtable_name,

column_name,

segment_name,

tablespace_name,

in_row,

securefile

FROMuser_LOBs

WHEREtable_namein('EMP_BASIC','EMP_SECURE')

)

SELECT*FROMc

UNPIVOT

(column_valueFORcolumn_nameIN

(table_name,column_name,segment_name,tablespace_name,in_row,securefile))

/

COLUMN_NAMECOLUMN_VALUE

--------------------------------------------------

TABLE_NAMEEMP_BASIC

COLUMN_NAMEMISC_DOCS

SEGMENT_NAMESYS_LOB0000093890C00007$$

TABLESPACE_NAMETBS_BASIC

IN_ROWYES

SECUREFILENO

TABLE_NAMEEMP_SECURE



TABLESPACE_NAMETBS_SECURE

IN_ROWYES

SECUREFILEYES

ThefollowingqueryshowsthesegmentspaceallocationandinitialextentsandblocksallocatedforBasicFileLOBandSecureFileLOB:

/*QueryUSER_SEGMENTStoqueryinitialbytesforLOB*/

WITHCAS

(

SELECTtable_name,

column_name,

l.segment_name,

s.segment_type,

s.segment_subtype,

to_char(s.bytes/1024)asbytes

FROMuser_LOBsl,user_segmentss

WHEREl.segment_name=s.segment_name

ANDl.table_namein('EMP_BASIC','EMP_SECURE')

)

SELECT*FROMC

UNPIVOT

(column_valueFORcolumn_nameIN

(table_name,column_name,segment_name,segment_type,segment_subtype,bytes))

/

COLUMN_NAMECOLUMN_VALUE

-----------------------------------------------------------

TABLE_NAMEEMP_BASIC



SEGMENT_TYPELOBSEGMENT

SEGMENT_SUBTYPEMSSM

BYTES64

TABLE_NAMEEMP_SECURE



SEGMENT_TYPELOBSEGMENT

SEGMENT_SUBTYPESECUREFILE

BYTES128

TheprecedingqueryoutputshowsthataSecureFileneedsaminimumof16blocks(thatis,128/8)inthefirstextent.Atthesametime,BasicFilerequiresaminimumof3blocksintheinitialextent.However,thequeryresultshowstheallocationof8extentsfortheEMP_BASIC.MIS_DOCScolumns.

TemporaryLOBmetadatacanbequeriedfromtheV$TEMPORARY_LOBSdictionaryview.

EnablingtheadvancedfeaturesofaSecureFileLet’scheckwhethertheadvancedfeatures,thatis,compression,deduplication,andencryptionforaSecureFileLOBareenabledornot:

/*QueryUSER_LOBStoviewadvancedfeaturesofSecureFile*/

SELECTcolumn_name,

encrypt,

compression,

deduplication

FROMuser_LOBs

WHEREtable_name='EMP_SECURE'

/

COLUMN_NAMENCRCOMPREDEDUPLICATION

-----------------------------------

MISC_DOCSNONONO

Theoutputfromtheprecedingqueryshowsthatcompression,deduplication,andencryptionisnotyetswitchedonfortheMISC_DOCScolumnintheEMP_SECUREtable.YoucanusetheALTERTABLEcommandtoenablecompressionanddeduplicationfortheSecureFileLOBcolumn:

/*ModifytheMISC_DOCStoenablecompressionanddeduplication*/

ALTERTABLEemp_secure

MODIFYLOB(misc_docs)

(

COMPRESSHIGH

DEDUPLICATE

)

/

Tablealtered.

Let’sverifythechangesfromtheUSER_LOBStable:


SELECTcolumn_name,

encrypt,

compression,

deduplication

FROMuser_LOBs


/


-----------------------------------

MISC_DOCSNOHIGHLOB

YoucanalsoenabletheLOBencryptionfortheMISC_DOCStableusingtheALTERTABLEcommand.ASecureFilesupportsthefollowingencryptionalgorithms:

3DES168:Thisisthetripledataencryptionstandardwitha168-bitkeysizeAES128:Thisistheadvanceddataencryptionstandardwitha128-bitkeysizeAES192:Thisisthedefaultencryptionalgorithm.Itistheadvanceddataencryption

standardwitha192-bitkeysizeAES256:Thisistheadvanceddataencryptionstandardwitha256-bitkeysize

Thefollowingprogrammodifiesacolumntoenableencryption:

/*ModifyMISC_DOCScolumntoenableencryption*/


MODIFY

(

misc_docsENCRYPTUSING'AES192'

)

/


*

ERRORatline1:

ORA-28365:walletisnotopen

Youmightreceivetheprecedingexceptioniftheencryptionwalletisnotopen.Wewillnowauthenticatethewalletbysettingapassword:


ALTERsystem

SETENCRYPTIONKEY

IDENTIFIEDBY"orcl"

/

Systemaltered.

Usingtheprecedingpassword,youcanauthenticateandopenthewallet:

ALTERsystem

SETENCRYPTIONWALLETOPEN

IDENTIFIEDBY"orcl"

/

Systemaltered.

Oncethewalletisopened,itwillcreateafile,ewallet.p12,inthedefaultwalletdirectory:

[oracle@oradev12cwallet]$ll

total4

-rw-r--r--.1oracleoinstall2848May1606:54ewallet.p12

YoucanalsocheckthewalletstatusfromtheV$ENCRYPTION_WALLETdictionaryview:

/*QueryV$ENCRYPTION_WALLETtocheckthewalletstatus*/

SELECTwrl_type,

wrl_parameter,

status

FROMv$encryption_wallet

/

WRL_TYPEWRL_PARAMETERSTATUS

--------------------------------------------------------------

FILE/u01/app/oracle/admin/orcl/walletOPEN

Let’sreruntheALTERTABLEcommandtoenableencryptionfortheMISC_DOCScolumn:

connscott/tiger

/*ModifytheMISC_DOCStoenableencryption*/


MODIFY

(

misc_docsENCRYPTUSING'AES192'

)

/

Tablealtered.

YoucanverifytheadvancedsettingfeatureundertheUSER_LOBSdictionaryview:


SELECTcolumn_name,

encrypt,

compression,

deduplication

FROMuser_LOBs


/


-----------------------------------

MISC_DOCSYESHIGHLOB

PopulatingtheLOBdataThefollowingPL/SQLprocedurewritesanoperatingsystemfiletoaLOBcolumnagainstatablerecord.Itiscustomizedforourtestcasetoacceptthedirectoryname,filename,tablename,andemployeeID,forwhichthefilehastobeuploaded:


CREATEORREPLACEPROCEDUREupload_emp_docs

(p_dirVARCHAR2,

p_fileVARCHAR2,

p_tableVARCHAR2,

p_empnoNUMBER)

IS

/*DeclaringLOBlocatorfortheBLOB*/

L_SOURCE_BLOBBFILE;

/*DeclaringoffsetvaluefortheLOBcolumn*/

L_AMT_BLOBINTEGER:=4000;

/*DeclaringtemporaryLOBcolumnsfortheLOBcolumn*/

L_BLOBBLOB:=EMPTY_BLOB();

L_STMTCLOB:=EMPTY_CLOB();

BEGIN

/*CreateaBFILElocatorfortheexternalfile*/

L_SOURCE_BLOB:=BFILENAME(p_dir,p_file);

/*CreateatemporaryLOB*/

DBMS_LOB.CREATETEMPORARY(l_bLOB,true);

/*OpeningtheLOBlocatorinreadonlymode*/

DBMS_LOB.OPEN(L_SOURCE_BLOB,DBMS_LOB.LOB_READONLY);

/*CalculatingthelengthofLOBlocator*/

L_AMT_BLOB:=DBMS_LOB.GETLENGTH(L_SOURCE_BLOB);

/*LoadthetemporaryLOBswiththeLOBlocator*/

DBMS_LOB.LOADFROMFILE(L_BLOB,L_SOURCE_BLOB,L_AMT_BLOB);

/*ClosetheLOBlocators*/

DBMS_LOB.CLOSE(L_SOURCE_BLOB);

/*UpdatethetablewiththetemporaryLOBvariable*/

L_STMT:='UPDATE'||p_table||'SETmisc_docs=:p2WHEREempno=:p3';

EXECUTEIMMEDIATEl_stmtusingl_bLOB,p_empno;

IFSQL%ROWCOUNT=0THEN

DBMS_OUTPUT.PUT_LINE('Wronginput-Employeedoesnotexsts');

ELSE

DBMS_OUTPUT.PUT_LINE('Documentuploadedsuccessfullyforemployee

'||p_empno);

ENDIF;

END;

/

Procedurecreated.

Let’stesttheprocedurebyuploadingaPDFfileforalltheemployees.Beforeweruntheprocedure,youmustcreateadirectorypointingtothefilelocationandgrantthereadwriteprivilegeonthedirectorytotheSCOTTuser.Notethatthedatabasedirectorymustpointtoavalidlocationontheserveroperatingsystem;thereasonbeingthatthedirectorylocationisvalidatedatthetimeofthedirectoryexecutiononly:


CREATEORREPLACEDIRECTORYsecure_dirAS'/u01/app/oracle/LOBs/'

/

Directorycreated.

GRANTREAD,WRITEONDIRECTORYsecure_dirTOSCOTT

/

Grantsucceeded.

ThefollowingPL/SQLblockcallstheUPLOAD_EMP_DOCSproceduretouploadthePDFfilesintheEMP_BASICandEMP_SECUREtableforalltheemployees:

SETSERVEROUTOFF

BEGIN

FORIIN(SELECTrownum,empnoFROMemp)

LOOP

/*CalltheproceduretoloadinEMP_BASICtable*/

upload_emp_docs('SECURE_DIR',

'ebook'||i.rownum||',pdf',

'EMP_BASIC',

i.empno);

/*CalltheproceduretoloadinEMP_SECUREtable*/

upload_emp_docs('SECURE_DIR',

'ebook'||i.rownum||',pdf',

'EMP_SECURE',

i.empno);

ENDLOOP;

END;

/


YoucancheckthesizeofthefileuploadedagainstanemployeeusingtheDBMS_LOB.GETLENGTHfunction:

/*VerifythesizeoftheBLOBinarow*/

SELECTempno,DBMS_LOB.GETLENGTH(misc_docs)

FROMemp_secure

WHEREempno=7839

/

EMPNODBMS_LOB.GETLENGTH(MISC_DOCS)

---------------------------------------

78395769744

YoucancheckthenumberofextentsandblocksallocatedforBasicFileandSecureFileusingthefollowingquery:

/*QueryUSER_SEGMENTStocomparethetotalblocksconsumed*/

SELECTtable_name,

l.segment_name,

bytes/1024KB,

blocks,

extents

FROMuser_LOBsl,user_segmentss

WHEREl.segment_name=s.segment_name

ANDl.table_namein('EMP_BASIC','EMP_SECURE')

/

TABLE_NAMESEGMENT_NAMEKBBLOCKSEXTENTS

------------------------------------------------------------

EMP_BASICSYS_LOB0000093890C00007$$819201024081

EMP_SECURESYS_LOB0000093893C00007$$73609209

TemporaryLOBoperationsAtemporaryLOBenablestheLOBoperationssuchascreationandmodificationoftheLOBcolumnvalues.AtemporaryLOBconsumesspaceinatemporarytablespacebutitmustbefreedafterusage.TheDBMS_LOBpackageprovidestheAPIstohandletemporaryLOBactions.

ManagingtemporaryLOBsTheDBMS_LOBpackageofferssubprogramsfortemporaryLOBs.TheDBMS_LOBsubprogram,ISTEMPORARY,determineswhetheragivenLOBistemporaryornot.Syntactically,theoverloadedsubprogramisasfollows:

DBMS_LOB.ISTEMPORARY(LOB_locINBLOB)

RETURNINTEGER;

DBMS_LOB.ISTEMPORARY(LOB_locINCLOBCHARACTERSETANY_CS)

RETURNINTEGER;

Inthesyntax,LOB_LOCistheLOBlocator.ALOBlocatorcanbeaCLOBorBLOBtypevariable.

TocreateatemporaryLOB,youusetheDBMS_LOB.CREATETEMPORARYsubprogram.ItisanoverloadedAPItoallowtheLOBlocatorfromafixedorvariablecharacterset:

DBMS_LOB.CREATETEMPORARY

(

LOB_locINOUTNOCOPYBLOB,

cacheINBOOLEAN,

durationINPLS_INTEGER:=DBMS_LOB.SESSION

);


(

LOB_locINOUTNOCOPYCLOBCHARACTERSETANY_CS,

cacheINBOOLEAN,

durationINPLS_INTEGER:=10

);

Intheprecedingsubprogramsignatures:

LOB_loc:ThisistheLOBlocator.cache:ThisisthebooleanparametertospecifywhethertheLOBshouldbecachedinthebuffercacheornot.duration:ItspecifiesthelifeofthetemporaryLOB.ItcanbeoneofSESSION,TRANSACTION,orCALL.ThedefaultdurationofatemporaryLOBisSESSION.

DBMS_LOB.FREETEMPORARYfreesthememoryallocatedforthetemporaryLOB.Thesyntaxfortheoverloadedsubprogramisasfollows:

DBMS_LOB.FREETEMPORARY(LOB_locINOUTNOCOPYBLOB);

DBMS_LOB.FREETEMPORARY(LOB_locINOUTNOCOPYCLOBCHARACTERSETANY_CS);

WorkingwithatemporaryLOBLet’swriteaPL/SQLprogramtoillustratetheusageofthetemporaryLOBsubprograms.Weshallobservethecreation,validation,andreleaseofthetemporaryLOBintheprogram:

/*EnabletheSERVEROUTtodisplaytheblockoutput*/

SETSERVEROUTPUTON


DECLARE

L_TEMP_LOBCLOB;

AMTNUMBER;

OFFSETNUMBER:=5;

L_WRITEVARCHAR2(100):='Oracle8iintroducedLOBtypes';

L_APPENDVARCHAR2(100):='Oracle11gintroducedSecureFiles';

BEGIN

/*CreatethetemporaryLOB*/


(

LOB_loc=>L_TEMP_LOB,

cache=>true,

dur=>dbms_LOB.session

);

/*VerifythecreationoftemporaryLOB*/

IF(DBMS_LOB.ISTEMPORARY(L_TEMP_LOB)=1)THEN

DBMS_OUTPUT.PUT_LINE('GivenLOBisatemporaryLOB');

ELSE

DBMS_OUTPUT.PUT_LINE('GivenLOBisapersistentLOB');

ENDIF;

/*OpenthetemporaryLOBisreadwritemode*/

DBMS_LOB.OPEN

(


open_mode=>DBMS_LOB.LOB_READWRITE

);

/*WritethesampledatainthetemporaryLOB*/

DBMS_LOB.WRITE

(


amount=>LENGTH(L_WRITE),

offset=>OFFSET,

buffer=>L_WRITE);

DBMS_OUTPUT.PUT_LINE

(

'TemporaryLOBlengthafterWrite'||DBMS_LOB.GETLENGTH(L_TEMP_LOB)

);

/*AppendthesampleinthetemporaryLOB*/

DBMS_LOB.WRITEAPPEND

(


amount=>LENGTH(L_APPEND),

buffer=>L_APPEND

);


(

'TemporaryLOBlengthafterAppend'||DBMS_LOB.GETLENGTH(L_TEMP_LOB)

);

/*DisplaythecompletecontentofthetemporaryLOB*/


(

CHR(10)||'TemporaryLOBContent:'

);


(

DBMS_LOB.SUBSTR

(

L_TEMP_LOB,DBMS_LOB.GETLENGTH

(L_TEMP_LOB),1

)

);

DBMS_LOB.CLOSE(LOB_loc=>L_TEMP_LOB);

DBMS_LOB.FREETEMPORARY(LOB_loc=>L_TEMP_LOB);

END;

/

GivenLOBisatemporaryLOB

TemporaryLOBlengthafterWrite34

TemporaryLOBlengthafterAppend67

TemporaryLOBContent:

Oracle8iintroducedLOBtypesOracle11gintroducedSecureFiles


MigratingLONGtoLOBsThedatabaseapplicationsusingLONGdatatypesshouldmigratetoLOBduetothefollowingreasons:

ALONGcolumncanstoreamaximumof(2GB-1)whileanLOBcanstoreamaximumdataof(4GB-1)Atablecanhaveone,andonlyone,LONGdatatypecolumnwhilethereisnorestrictiononthenumberofLOBcolumnsinatableDatareplicationisnotallowedwiththeLONGandLONGRAWcolumns

TipMigratingLONGtotheLOBcolumnsmaygeneratealotofredo.Therefore,itisadvisedtoswitchofftheloggingforthetablecontainingtheLONGcolumn.

YoucanconvertLONGtoCLOBandLONGRAWtoBLOBusingeitherofthefollowinglistedapproaches:

UsetheALTERTABLEcommandForatablewiththeLONGtypecolumn,youcanusetheALTERTABLEcommandtomodifythecolumntypetoLOBwithnewstoragespecificationsandmigratethedatatoanewspace.NotethatalltheLONGdataismigratedasLOBinthetable.Allthecolumn-levelcharacteristicsoftheLONGcolumnareretainedandcarriedforwardtotheLOBcolumn.Asabestpractice,youshoulddropthedomainindexesontheLONGcolumns,ifanyexist.

Forexample,thefollowingcommandconvertstheTEXTcolumnfromLONGtoLOB:

ALTERTABLEneed_to_migrateMODIFY(textCLOB)

/

UsingtheTO_LOBfunctionYoucanusetheTO_LOButilityfunctiontoconverttheLONGdataintoLOBwhileperformingtheCREATETABLEASSELECTorINSERTINTO..SELECTactions.ThismethodisbeneficialwhenyouwanttoperformtheconversionofasubsetoftheLONGvaluesbyapplyingpredicateclausestotheSELECTquery.ItcannotbeusedinaPL/SQLblock.

TheTO_LOBfunctionconvertsLONGtoCLOBorNCLOBandLONGRAWtoBLOBdata.Refertothefollowingexample:

CREATETABLEsales_new

AS

SELECTsales_id,sales_name,TO_LOB(sales_doc)

FROMsales_old

/

TheTO_LOBfunctioninaCTASoperationdoesn’tworkforanIndexOrganizedTable.However,theINSERTASSELECToperationonanindex-organizedtablestillworks.

OnlineTableRedefinitionOnlinetableredefinitionusestheTO_LOButilityfunctiontoperformtheLONGtoLOBconversion.Youhavetocreateawork-in-progresstableofthesamestructureastheoriginaltable.Notethatthistime,youwillusetheLOBcolumnsinplaceoftheLONGcolumns.Later,youcancallDBMS_REDEFINITION.START_REDEF_TABLEwiththerequiredparameterstokickofftheconversion.

MigratingBasicFilestoSecureFilesItisrecommendedtomigratetheBasicFileLOBstoSecureFileLOBsusingtheOnlineTableRedefinitionmethod.TheadvantageofusingtheOnlineTableRedefinitionmethodisthatnoneoftheobjectshavetobeofflineduringtheprocess.Inaddition,theperformanceoftheredefinitionprocesscanbeenhancedbyenablingparallelism.Thefollowingexampledemonstratestheonlineredefinitionprocess.

ATAB_BASICFILEtablecontainstheDOCcolumnthatisaBasicFileCLOBcolumn:

SELECT*

FROMtab_basicfile

/

IDDOC

-----------------------

1Oracle9i

2Oracle10g

3Oracle11g

4Oracle12c

ThefollowingquerycheckstheLOBbehaviorfromtheUSER_LOBSdictionaryview:

SELECTcolumn_name,

securefile

FROMuser_LOBs

WHEREtable_name='TAB_BASICFILE'

/

COLUMN_NAMESEC

----------------

DOCNO

Forredefinition,wewillcreateawork-in-progresstablewiththesamestructureastheTAB_BASICFILEtable.Youcandropthistableafterthetableredefinitionactivityisover.Notethatthistableshouldnothaveanyindexes.Duringtheredefinitionprocess,thetargettablewillcarrythesamedataastheoriginaltable.Therefore,thehostservermusthavesufficientfreespaceavailabletoperformtheredefinitionoperation:

/*CreatingtargettableTAB_SECUREFILEforredefinition*/

CREATETABLETAB_SECUREFILE

(idNUMBER,

docCLOB)

LOB(doc)STOREASSECUREFILE

/

/*VerifytheSecureFilefeature*/

SELECTcolumn_name,

securefile

FROMuser_LOBs

WHEREtable_name='TAB_SECUREFILE'

/

COLUMN_NAMESEC

----------------

DOCYES

Youcankick-startthetableredefinitionoperationbycallingtheDBMS_REDEFINITION.START_REDEF_TABLEsubprogram:



DECLARE

L_ERRORPLS_INTEGER:=0;

BEGIN

/*Specifysourceandtargettablesforredefinition*/

DBMS_REDEFINITION.START_REDEF_TABLE

(uname=>'SCOTT',--Schemanameofthetables

orig_table=>'TAB_BASICFILE',--Tabletoberedefined

int_table=>'TAB_SECUREFILE',--Interimtable

col_mapping=>'idid,docdoc'--Columnmappingfrom

sourcetointerimtable

);

/*Specifysourceandtargettablesforcopyingthedependents*/

DBMS_REDEFINITION.COPY_TABLE_DEPENDENTS


orig_table=>'TAB_BASICFILE',--Originaltable

int_table=>'TAB_SECUREFILE',--Interimtable

copy_indexes=>1,--Copyindexes(1)ornot(0)

copy_triggers=>true,--Copytriggers(T)ornot(F)

copy_constraints=>true,--Copyconstraints(T)ornot(F)

copy_privileges=>true,--Copyprivileges(T)ornot(F)

ignore_errors=>false,--Ignoreerrorswhilecopyinga

dependentobject

num_errors=>L_ERROR,--Numberoferrorsoccurredwhile

copyingdependentobjects

copy_statistics=>FALSE,--Copystatistics(1)ornot(0)

copy_mvlog=>FALSE--Copymaterializedviewlog(1)or

not(0)

);

DBMS_OUTPUT.PUT_LINE('Errors:='||TO_CHAR(L_ERROR));

/*Finishtheredefinitionprocess*/

DBMS_REDEFINITION.FINISH_REDEF_TABLE


orig_table=>'TAB_BASICFILE',--Tabletoberedefined

int_table=>'TAB_SECUREFILE'--Interimtable

);

END;

/


YoucanuseDBMS_REDEFINITION.ABORT_REDEF_TABLEtoabortthetableredefinitionprocessifyouencountertheORA-23539:table"SCOTT"."TAB_BASICFILE"currently

beingredefinedexception.

Let’sverifytheSECUREFILEpropertyfortheTAB_BASICFILEtable:

SELECTcolumn_name,

securefile

FROMUSER_LOBS

WHERETABLE_NAME='TAB_BASICFILE'

/

COLUMN_NAMESEC

-----------------------

DOCYES

TAB_BASICFILEexchangesitstablepropertieswithTAB_SECUREFILE:

SELECTcolumn_name,securefile

FROMUSER_LOBS

WHERETABLE_NAME='TAB_SECUREFILE'

/

COLUMN_NAMESEC

-----------------------

DOCNO

OracleDatabase12cenhancementstoSecureFilesOracleDatabase12caddsthefollowingfeaturestotheSecureFileLOBs:

SecureFilesLOBwillbethedefaultstorage:YoumighthaveseenthispointearlierinthechaptersothisisjustreiteratingthefactthatSecureFileswillbethedefaultstorageoptioninOracleDatabase12c.Thevalueofthedb_securefileinitializationparameterisPREFERRED,whichmeansthatallLOBsontheASSMenabledtablespacewillbecreatedasSecureFiles(unlessBasicFileisexplicitlyspecifiedorthetablespaceisnonASSM).ParallelDMLsupportforLOBs:IfalltheLOBcolumnsinapartitionedornon-partitionedtableareSecureFiles,thenDMLoperationscanbeexecutedinparallel.DataPumpusesSecureFileasthedefaultLOBstorage:YoucannowmigrateaBasicFiletoSecureFileusingtheDataPumputility.Duringanexportdatapumpoperation,youcansettheTRANSFORMhandleasLOB_STORAGEtodecidehowtheLOBsegmentswillbecreatedinthetargetdatabase.TheLOB_STORAGEhandlecanbeSECUREFILE,BASICFILE,DEFAULT,orNO_CHANGE(default):TheNO_CHANGEoptiondoesnotmanipulatetheLOBstorage.TheDEFAULToptionfollowsthedefaultLOBstorageonthetargetdatabase.TheSECUREFILE|BASICFILEoptionsenablethecreationoftheLOBsegmentsasSecureFilesorBasicFiles.

SummaryInthischapter,youlearnedhowtohandlelargeobjectsinOracle.Younowunderstandthedynamicsofstoringlargeobjectsinadatabase.AdetaileddiscussionontheoptimizationfeaturesofOracleSecureFileswouldhavehelpedyoutodifferentiatethetwostorageapproaches.ThecomparativeillustrationofaBasicFileandSecureFilewillhelpindeducingtheappropriateconclusions.

Movingforward,thenextchapterwilldealwithanotherimportantaspectofdatabaseprogramming,thatis,tuningthePL/SQLcode.Tuning—anindispensablepartofprogramming—isaskillforwritingoptimizedcode,whichcomesfromknowledgeandmatureswithexperience.

PracticeexerciseInternalLOBscanbeusedasattributesofauser-defineddatatype:

1. True.2. False.

InternalLOBscannotbepassedasparameterstoPL/SQLsubprograms:

1. True.2. False.

InternalLOBscanbestoredinatablespacethatisdifferentfromthetablespacethatstoresthetablecontainingtheLOBcolumn:

1. True.2. False.

YouissuethefollowingcommandtocreateatablecalledLOB_STORE:

CREATETABLELOB_store

(LOB_idNUMBER(3),

photoBLOBDEFAULTEMPTY_CLOB(),

cvCLOBDEFAULTNULL,

ext_fileBFILEDEFAULTNULL)

/

Identifytheissueinthisscript:

1. Thetableiscreatedsuccessfully.2. ItgeneratesanerrorbecauseaBLOBcolumncannotbeinitializedwith

EMPTY_CLOB().3. ItgeneratesanerrorbecauseDEFAULTcannotbesettoNULLforaCLOBcolumn

duringtablecreation.4. ItgeneratesanerrorbecauseDEFAULTcannotbesettoNULLforaBFILEcolumn

duringtablecreation.

IdentifythecorrectstatementsrelatingtotheinitializationofLOBs:

1. AninternalLOBcannotbeinitializedintheCREATETABLEstatement.2. ABFILEcolumncanbeinitializedwiththeEMPTY_BFILE()constructor.3. TheEMPTY_CLOB()andEMPTY_BLOB()functionscanbeusedtoinitializeboth

theNULLandNOTNULLinternalLOBsoftheCLOBandBLOBtypes.4. InitializationisamandatorystepforLOBtypecolumns.

WhichtwostatementsaretrueabouttheFILEOPENsubprogramintheDBMS_LOBpackage?

1. FILEOPENcanbeusedtoopenonlyinternalLOBs.2. FILEOPENcanbeusedtoopenonlyexternalLOBs.3. FILEOPENcannotbeusedtoopentemporaryLOBs.4. FILEOPENcanbeusedtoopeninternalandexternalLOBs.

TemporaryLOBscanbesharedamongtheuserswhoarecurrentlyconnectedtotheserver:

1. True.2. False.

IdentifythecorrectstatementsaboutBFILEs:

1. ABFILEcolumninatablemustbeinitializedwithadummylocator.2. BFILEscannotbeusedasattributesinanobjecttype.3. TheBFILEdatatypeisaread-onlydatatype.4. TheexternalfilestillpersistsiftheBFILElocatorisdeletedormodified.

PicktheincorrectstatementsaboutTemporaryLOBs:

1. Itresidesintheuser’stemporarytablespace.2. ItcanbeusedduringtheLONGtoLOBdatatypemigration.3. ItcanbepersistentforSESSION,TRANSACTION,orCALL.4. TemporaryLOBofaBFILEtypecanbecreated.

ASAMPLE_DATAtablehasthefollowingstructure:

NameNull?Type

------------------

SD_IDNUMBER

SD_SOURCEBFILE

YouupdatearowinthetableusingtheUPDATEstatement,asfollows:

UPDATEsample_data

SETsd_source=BFILENAME('SD_FILE','sample.pdf')

WHEREsd_id=448;

However,youreceivetheerror—ORA-22286:insufficientprivileges—onthefileordirectorytoperformFILEOPEN.

Whatcouldbetheprobablecauseofthiserror?

1. ThedirectorySD_FILEdoesnotexist.2. Thefilesample.pdfdoesnotexist.3. TheuserdoesnothavetheREADprivilegeonthedirectory.4. Thefilesample.pdfisaread-onlyfile.

WhichofthefollowingstatementsaboutSecureFilesaretrue?

1. SecureFilesrequireanASSM-enabledtablespace.2. ABFILEtypecolumninatablecanbedeclaredasSecureFiles.3. ASecureFileisnotaffectedbyaLOBindexcontention.4. SecureFilesuseanewcachecomponentofthebuffercachetoholdtheLOBdata.

IdentifytheincorrectstatementaboutthecompressionfeatureinSecureFiles:

1. CompressionimpactsperformanceduringaLOBwriteoperation.2. SecureFilescompressionispartoftheadvancedcompressionfeatureinOracle.3. PossibledegreesofcompressioncanbeMEDIUMandHIGH.4. OraclecompressesalltheLOBdataathighpriorityifthefeaturehasbeen

enabledforaSecureFile.

ThecompressionfeaturecanbeenabledonlyforencryptedSecureFiles:

1. True.2. False.

AcompressedtablecontainingaSecureFilecolumnwillautomaticallyenablecompressionforSecureFiles:

1. True.2. False.

IdentifythetruestatementsaboutthededuplicationfeatureofSecureFiles:

1. KEEP_DUPLICATESisthedefaultoption.2. DEDUPLICATEretainsonecopyoftheduplicateLOBdata.3. ThededuplicationfeatureimpactswriteperformanceasOraclecomparesthe

securehashcodewiththeavailablehashcodesbeforewritingtothedisk.4. ThededuplicationofSecureFilesischeckedonthebasisofthefilenames.

PickthecorrectstatementfortheencryptionfeatureinSecureFiles:

1. TheSecureFileencryptionkeysarestoredinthetable.2. TheSecureFileencryptionkeysarestoredinthedatabase.3. TheSecureFileencryptionkeysarestoredoutsidethedatabase.4. EncryptionalgorithmscannotbemodifiedforanencryptedSecureFilecolumn.

WhichofthefollowingstatementsaretrueforBasicFiletoSecureFilemigrationinOracle?

1. TheBasicFiletoSecureFilemigrationcanbedonethroughadatapumpoperation.

2. Tableredefinitionispreferredasitdoesthemigrationwithalltheresourcesconnectedonline.

3. TheDBMS_REDEFINITIONpackagecanmigrateonlyoneLOBcolumnatatime.4. Unnecessaryspaceconsumptionmakestheredefinitionprocesslesspreferable

overthepartitionmethod.

Chapter8.TuningthePL/SQLCodeDatabasetuningreferstoanexercisethataimstoimprovetheperformanceofadatabase.Theartofoptimizingthedatabaseperformancelargelydependsonhowwelloneunderstandsthedatabasearchitecture,applicationdesignandserverenvironment.Theareasthatcanbepotentiallytunedaretheapplicationdesign,network,SQLqueries,andPL/SQLcode.Thisexercisestartswiththedetectionandidentificationofaproblem,followedbyanalysisandtuningrecommendations.Inthischapter,wewillseetuningpracticesrelatedtotheOraclePL/SQLcode.

ProgramswritteninOraclePL/SQLcanbetunedtooptimizedata-centricandCPU-intensiveoperations.InaPL/SQLprogramunit,statementslikeloops,dynamicSQLstatements,routinecalls,andthecompilationmodecanbetunedforbetterperformance.Thischapterwilldiscussthedifferentcodecompilationtechniquesandtheirbenefits.Thechapteroutlineisasfollows:

ThePL/SQLCompiler

Subprograminline

NativecompilationofthePL/SQLCodeTuningthePL/SQLCode

BuildsecureapplicationsusingbindvariablesCallparametersbyreferenceAvoidanimplicitdatatypeconversionUnderstandtheNOTNULLconstraintSelectanappropriatenumericdatatypeBulkprocessinginPL/SQL

ThePL/SQLCompilerThePL/SQLcompilerconvertsapieceofPL/SQLcodethatiswritteninuser-readablelanguagesemanticstosystemcode.Atahigherlevel,thecodecompilationisathree-stepprocessthatincludescodeparsing,parameterbinding,andtranslationintomachinecode(M-code).ThecompilerraisesasyntaxorcompilationerrorifaPL/SQLconstructorstatementisincorrectlyused.OncethePL/SQLprogramcodeiserror-freeandargumentbindingisdone,thesystemcodeisgeneratedandstoredinthedatabase.

UntilOracle10gRelease1,theM-codewasgeneratedwithoutanycodeoptimization.StartingfromOracleDatabase10gRelease2,M-codeusesthePL/SQLoptimizertoapplycodeformattingforbetterperformance.ThePL/SQLoptimizerlevelisgovernedbyacompilationparameterknownasPLSQL_OPTIMIZE_LEVEL.Theparametervaluecanbesetatthesystemorsessionlevelasanumberbetween1to3.Bydefault,theparametervalueis2.

ThePL/SQLoptimizerusesmultipletechniquestooptimizethePL/SQLcode,forexample,theremovalofdeadcodefromtheprogramunit,orinliningthecallstosubprograms.Letusfirstseehowsubprograminliningworks.

SubprograminlininginPL/SQLAPL/SQLprogramunitwithalocally-declaredandinvokedsubprogramcanbeoptimizedusingtheinliningmethod.Whileoptimizingtheprogramcode,thePL/SQLoptimizerreplacesthesubprograminvocationcallsbythesubprogrambodyitself.ForthePL/SQLcompilertoinlinealocalsubprogram,thefollowingcriteriamustbemet:

SetPLSQL_OPTIMIZE_LEVELto2andusePRAGMAINLINE:ThecompilerinlinesonlythosesubprogramsthatarespecifiedwithPRAGMAINLINE.SetPLSQL_OPTIMIZE_LEVELto3:Thecompilerinlinesallthesubprogramcalls.However,youcanspecifyPRAGMAINLINEtopreventtheinliningofaparticularsubprogram.Todisabletheinliningofaprogramunit,specifyPRGMAINLINE([subprogramunit],'NO').

PRAGMAINLINEdirectsthecompilertoinlinethesubprogramcallsthatarejustsucceedingit.Forexample,inthefollowingPL/SQLblock,thesubprogramcallisinlinedinLine5butnotinLine7:

PROCEDUREP_SUM_NUM(P_ANUMBER,P_BNUMBER)/*Line1*/

.../*Line2*/

BEGIN/*Line3*/

PRAGMAINLINE('P_SUM_NUM','YES')/*Line4*/

result_1:=P_SUM_NUM(10,20);/*Line5*/

..../*Line6*/

result_2:=P_SUM_NUM(100,200);/*Line7*/

END;/*Line8*/

//*Line9*/

Atmostofthescenarios,subprograminliningimprovestheperformanceofaPL/SQLprogram.Ifthesubprogramisalargeunit,thecostofinliningwouldbemorethanthemodularexecution.

NotePRAGMAINLINE([subprogram],'NO')willalwaysoverridePRAGMAINLINE([subprogram],'YES')inthesamedeclaration.

ItisrecommendedthatyouinlinethoseutilitysubprogramsthatarefrequentlyinvokedinaPL/SQLblock.Theintra-unitinliningistraceablethroughsession-levelwarnings.Thesession-levelwarningscanbeturnedonbysettingthePLSQL_WARNINGSparametertoENABLE:ALL.

PRAGMAINLINEPRAGMAisacompilerdirectivethathintsthecompiler.AnyerrorintheusageofPRAGMAresultsinacompilationerror.NotethataPRAGMA,whichacceptsanargument,cannotacceptaformalargumentbutalwaysneedsanactualargument.

PRAGMAINLINEwasintroducedinOracleDatabase11gtosupportsubprograminliningforbetterPL/SQLperformance.WhenthecompilationparameterPLSQL_OPTIMIZE_LEVELis2,youhavetospecifythesubprogramtobeinlinedusingPRAGMAINLINE.When

PLSQL_OPTIMIZE_LEVELis3,thePL/SQLoptimizertriestoinlinemostofthesubprogramcalls,withoutrequiringanyPRAGMAspecification.Atthisstage,ifyouperceiveaninlinedsubprogramtobeirrelevantorundesirable,youcandisabletheinliningofthatparticularsubprogramthroughPRAGMAINLINE.

NotePRAGMAINLINEimpactsonlywhenPLSQL_OPTIMIZE_LEVELiseither2or3.WhenPLSQL_OPTIMIZE_LEVELis1,ithasnoeffect.

PLSQL_OPTIMIZE_LEVELOracleDatabase10gintroducedthePLSQL_OPTIMIZE_LEVELinitializationparametertoenableordisablePL/SQLoptimization.Ifenabled,theoptimizerdeploysseveraloptimizationtechniquesinaccordancewiththelevel.ThecompilationsettingsofaPL/SQLprogramcanbequeriedfromtheUSER_PLSQL_OBJECT_SETTINGSdictionaryview.

UntilOracleDatabase10g,theparametervaluecouldbeeither0,1,or2.StartingfromOracleDatabase11g,thenewoptimizationlevelcanbeenabledbysettingtheparametervalueto3.Notethatthedefaultvalueoftheparameteris2.TheparametervaluecanbemodifiedusingtheALTERSYSTEMorALTERSESSIONstatements.OnlythePL/SQLprogramsthatarecompiledaftertheparametermodificationareimpacted.YoucanalsospecifythePLSQL_OPTIMIZE_LEVELvalueatthetimeofexplicitcompilationofaprogramunit.Forexample,aP_OPT_LVLprocedurecanberecompiledusingthefollowingstatement:

ALTERPROCEDUREp_opt_lvlCOMPILEPLSQL_OPTIMIZE_LEVEL=1

/

ThefollowingPL/SQLproceduredemonstratesthesubprograminliningusingPRAGMAINLINE.Theprocedureaddstheseries(1*2)+(2*2)+(3*2)+…+(N*2)uptoNterms:

/*Createaprocedure*/

CREATEORREPLACEPROCEDUREP_SUM_SERIES(p_countNUMBER)

IS

l_seriesNUMBER:=0;

l_timeNUMBER;

/*Declarealocalsubprogramwhichreturnsthedoubleofanumber*/

FUNCTIONF_CROSS(p_numNUMBER,p_multiplierNUMBER)RETURNNUMBERIS

l_resultNUMBER;

BEGIN

l_result:=p_num*p_multiplier;

RETURN(l_result);

ENDF_CROSS;

BEGIN

/*Capturethestarttime*/

l_time:=DBMS_UTILITY.GET_TIME();

/*Begintheloopforseriescalculation*/

FORJIN1..p_count

LOOP

/*Setinliningforthelocalsubprogram*/

PRAGMAINLINE(F_CROSS,'YES');

l_series:=l_series+F_CROSS(J,2);

ENDLOOP;

/*Timeconsumedtocalculatetheresult*/

DBMS_OUTPUT.PUT_LINE('Executiontime:'||TO_CHAR(DBMS_UTILITY.GET_TIME()

-L_TIME));

END;

/


Atlevel0,thePL/SQLoptimizerdoesn’tkickin,sonocodeoptimizationisenabled.Thecompilermaintainsthecodeevaluationorder,andperformsobjectchecks.

EnablePLSQL_WARNINGStocapturetheinlineoperations:

ALTERSESSIONSETplsql_warnings='enable:all'

/

Sessionaltered.

Let’srecompiletheP_SUM_SERIESprocedurewiththePLSQL_OPTIMIZE_LEVEL=0setting:

ALTERPROCEDUREP_SUM_SERIESCOMPILEPLSQL_OPTIMIZE_LEVEL=0

/

SP2-0804:Procedurecreatedwithcompilationwarnings

showerrors

ErrorsforPROCEDUREP_SUM_SERIES:

LINE/COLERROR

----------------------------------------------------------------

1/1PLW-05018:unitP_SUM_SERIESomittedoptionalAUTHIDclause;

defaultvalueDEFINERused

Let’sexecutetheprocedurewitharelativelylargeinputvalueforacomputation-intensiveoperation:

BEGIN

p_sum_series(10000000);

END;

/

Executiontime:776



Atlevel1,thePL/SQLoptimizerappliesconventionaloptimizationtechniquestoa

PL/SQLprogramunit.Iteliminatesthedeadcode,andskipstheredundantandunnecessarycodeintheprogramwhilegeneratingthep-codeinstructions.

Whatisdeadcode?IfaPL/SQLstatementremainsunchangedwithinaniterativeorconditionalconstruct,anddoesn’tcontributetotheprogramlogic,itisknownasdeadcode.Whiletranslatingtheprogramintothesystemcodeinstructions,thePL/SQLoptimizeridentifiesthepiecesofdeadcodeandpreventstheirconversion.

Let’srecompiletheP_SUM_SERIESprocedureusingtheALTERPROCEDUREstatementforPLSQL_OPTIMIZE_LEVEL=1andcheckthewarnings:

ALTERPROCEDUREP_SUM_SERIESCOMPILEPLSQL_OPTIMIZE_LEVEL=1

/

SP2-0804:Procedurecreatedwithcompilationwarnings

showerrors


LINE/COLERROR

----------------------------------------------------------



YoucanalsoquerythecompilationwarningsfromtheUSER_ERRORSdictionaryview.

AlthoughPRAGMAwasspecified,theF_CROSSinvocationwasnotinlined.Therefore,thesubprograminliningdoesn’tseemtoworkwhenPLSQL_OPTIMIZE_LEVELissetto1:

BEGIN

P_SUM_SERIES(10000000);

END;

/

Executiontime:710



Atlevel2,thePL/SQLoptimizerperformstheintelligentcodeoptimizationthroughtechniqueslikeexplicitsubprograminliningandcodereorganization.

RecompiletheP_SUM_SERIESprocedurewithPLSQL_OPTIMIZE_LEVEL=2usingtheALTERPROCEDUREstatement:

ALTERPROCEDUREp_sum_seriesCOMPILEPLSQL_OPTIMIZE_LEVEL=2

/

SP2-0805:Procedurealteredwithcompilationwarnings

Let’sretrievethecompilationwarnings.Oracleincludesanewsetofcompilationwarningstodemonstratetheinliningflowintheprogram.ThePL/SQLoptimizerisinstructedbyPRAGMAtoinlinethesubprograminline28.Atline8,thefunctionwasremovedanditsbodywasmergedintothemainprogram.Line28showstheinliningrequestandaction:

SQL>showerrors


LINE/COLERROR

---------------------------------------------------------



8/3PLW-06006:uncalledprocedure"F_CROSS"isremoved.

28/7PLW-06004:inliningofcallofprocedure'F_CROSS'requested

28/7PLW-06005:inliningofcallofprocedure'F_CROSS'wasdone

Let’scheckhowalevel2-optimizedandcompiledprogramperforms:

BEGIN


END;

/

Executiontime:456


Welldone!Itrunsin456ms,whichisalmosthalfofitsbaseline,thatis,2timesbetterperformance.


Level3optimizationfocusesonthepredictiveandautomaticinliningandcoderefactoring.Modifythecompilationparameterinthesessionusingthefollowingstatement:

ALTERSESSIONSETplsql_optimize_level=3

/

Sessionaltered.

Toseetheimplicitinliningofthesubprogram,let’srecreatetheP_SUM_SERIESprocedurewithoutthePRAGMAspecification:

/*Createaprocedure*/

CREATEORREPLACEPROCEDUREP_SUM_SERIES(p_countNUMBER)

IS

l_seriesNUMBER:=0;

l_timeNUMBER;

/*Declarealocalsubprogramtoreturnthedoubleofanumber*/

FUNCTIONF_CROSS(p_numNUMBER)RETURNNUMBERIS

BEGIN

RETURN(p_num*2);

ENDF_CROSS;

BEGIN


l_time:=DBMS_UTILITY.GET_TIME();

/*Begintheloopforseriescalculation*/

FORJIN1..p_count

LOOP

/*Setinliningforthelocalsubprogram*/

l_series:=l_series+F_CROSS(J);

ENDLOOP;

/*Timeconsumedtocalculatetheresult*/

DBMS_OUTPUT.PUT_LINE('Executiontime:'||TO_CHAR(DBMS_UTILITY.GET_TIME()

-L_TIME));

END;

/

SP2-0805:Procedurealteredwithcompilationwarnings

Let’scheckthecompilationwarnings:

showerrors


LINE/COLERROR

----------------------------------------------------------



8/3PLW-06006:uncalledprocedure"F_CROSS"isremoved.

25/7PLW-06005:inliningofcallofprocedure'F_CROSS'wasdone

Notethewarningsatline8andline24.NoPRAGMAspecified,butthePL/SQLoptimizerinlinesthesubprogram.Let’sseehowtheprocedureexecutionisimpactedbylevel3optimization:

BEGIN


END;

/

Executiontime:420


Theexecutiontimeisalmostequaltothelevel2optimization,becausethetechniquetooptimizethecodewassimilarinboththecases.

Theconsolidationoftheexecutionnumbersisshowninthefollowingtable:

PLSQL_OPTIMIZE_LEVEL InliningRequested InliningDone Executiontime Performancefactor

PLSQL_OPTIMIZE_LEVEL=0 Yes No 776 1

PLSQL_OPTIMIZE_LEVEL=1 Yes No 710 1.1x

PLSQL_OPTIMIZE_LEVEL=2 Yes Yes 456 1.7x

PLSQL_OPTIMIZE_LEVEL=3 No Yes 420 1.8x

Note

ItisrecommendedthatyouhavePLSQL_OPTIMIZE_LEVELas2forthedatabasedevelopmentandproductionenvironments.ItideallyoptimizesthePL/SQLcodeandenablesthedatabasedeveloperstocontrolthesubprograminlining.

NativeandinterpretedcompilationtechniquesUntilOracle9i,allPL/SQLprogramunitswerecompiledininterpretedmode.StartingwithOracle9i,PL/SQLprogramscanbecompiledeitherininterpretedmodeornativemode.Let’squicklyunderstandwhatareinterpretedandnativecompilationmodes.

ThePL/SQLcompilergeneratesmachinecodefortheprogramunits.MachinecodeisasetofinstructionsstoredinthedatabasedictionariesthatrunsagainstthePL/SQLvirtualmachine(PVM).Atthetimeoftheprograminvocation,theM-codeisscannedbyoneofthesubroutinesinthePVM.Thescanningprocessinvolvestheidentificationoftheoperationcodeandoperandsandroutingthecalltotheappropriatesubroutine.Thescanningofthemachinecodeinstructionsconsumessystemsresources,whichmayimpacttheruntimeperformanceofthecode.Thisishowinterpretedcompilationworks.Inthecaseofnativecompilation,ashareabledynamiclinkedlibrary(DLL)isgeneratedinsteadofamachinecode.Atruntime,theDLLisdirectlyinvokedanditinvokesthesubroutinealongwiththerequiredsetofarguments.WithDLL,youdon’thavetogothroughthescanningprocedureatruntime,whichcontributestobettercodeperformance.

UntilOracleDatabase9iand10g,thechallengewithnativecompilationwastogenerateaplatform-specificshareableandnonportablelibrary.ItwasmadepossiblebytheCcompilerandlinkercommandslocatedin$ORACLE_HOME/plsql/spnc_commands,whichwouldcompileandlinktheCtranslationofthemachinecodetoaplatform-specificlibrary.InOracleDatabase9i,thelibrarieswerestoredonafilesystem,whileinOracleDatabase10g,thelibrarieswerestoredinacatalog(databasedictionary).Acopyofthesharedlibrarieswasstoredonafilesystemforbackupandoperating-systemoperations.ThefilesystemlocationusedtobespecifiedinPLSQL_NATIVE_LIBRARY_DIRandPLSQL_NATIVE_LIBRARY_SUBDIR_COUNT.Thesharedlibrarieswereautomaticallyextracted,restored,anddeletedfromthefilesystem.Ifanyofthefilesystemlibrarieswerelostordroppedaccidently,theywerere-extractedandrestoredinthefilesystemafterthedatabasewasrestarted.

NoteThesharedlibrariesgeneratedduringnativecompilationarestoredintheNCOMP_DLL$dictionary.

NativecompilationissupportedwiththeRealApplicationCluster(RAC)databaseoption.

ThisapproachworkedwelluntiltheproductionDBAsshowedreluctanceinhavingtheCcompileronproductionenvironmentsandprocuringanadditionalCcompilerlicense.

OracleDatabase11gRealNativeCompilationOracleDatabase11gintroducedtherealnativecompilationtechniquetoaddressthebelow:

RemovetheCcompilerandlinkerdependenciestogenerateplatformspecificlibrariesImprovecodecompilationperformanceNocompromisewiththeruntimeperformance

StartingfromOracleDatabase11g,theOracleDatabasecangenerateplatform-specificmachinecodefromPL/SQLcodeandstoreitinthedatabasecatalogoraninternaldictionarywithouttheinterventionofathirdpartyCcompiler.Thenativecodeisthenloadeddirectlyfromthecatalogwithoutstagingitonafilesystem.OracleDatabase11grealnativecompilationimprovesthecompilationperformancebyadegreeofmagnitude.

Thefollowinglistsummarizesthesalientfeaturesofrealnativecompilationprocess:

ThereisnodependencyonathirdpartyCCompiler.ThenativecodeisstoredintheSYSTEMtablespace.ThereisnoDBAtasktosetthefilesysteminitializationparameter.Thecompilationmethodiscontrolledbyaninitializationparameter:PLSQL_CODE_TYPE[native/interpreted].NativecompilationissupportedforalltypesofPL/SQLprogramunits.InINTERPRETEDmode,thePL/SQLcodeiscompiledtotheequivalentmachinecode.ThemachinecodeinstructionsarescannedduringtheruntimeandroutedtotheappropriatesubroutineonthePL/SQLVirtualMachine.InNATIVEmode,thePL/SQLcodeiscompiledtomachinecode,whichisdirectlytranslatedtotheplatform-specific.Atruntime,themachinecodeisexecutednativelybythePL/SQLVirtualMachine.Therealnativecompilationmodecanbesetatsystemlevel,sessionlevel,andobjectlevel.Anativelycompiledprogramunitcancallaninterpretedprogramandviceversa.

SelectingtheappropriatecompilationmodeDuringthedatabasedevelopmentphase,thePL/SQLprogramunitstendtogetrecompiledfrequently.Atthisstage,youwouldwanttohavethefastercompilationofprograms.Therefore,youcanchoosetocompiletheprogramunitsininterpretedmode.

Oncethedatabaseisdeployedforproduction,andhasfewerchancesoffrequentrecompilation,youcanchoosenativecompilation.PL/SQLnativecompilationenhancestheruntimeperformanceoftheprogramunits.Computation-intensiveprogramsareexpectedtobenefitmostfromthenativecompilationmethod.TheperformancegainswillbelessiftheprogramisfrequentlyswitchingthecontextbetweentheSQLandPL/SQLengines.

Oracleallowshavingamixofprogramunitswithdifferentcompilationmodes.However,keepinmindthatifanativelycompiledunitinvokesaninterpretedunit,theprogramexecutionperformancewillbeimpacted.

SettingthecompilationmodeThecompilationmethodissetusingthePLSQL_CODE_TYPEparameter.TheadmissiblevaluesfortheparameterareINTERPRETEDandNATIVE.ThedefaultvalueoftheparameterisINTERPRETED.TheparametercanbesetusingtheALTERSYSTEMorALTERSESSIONstatement.

AttheSYSTEMlevel:

ALTERSYSTEMSETPLSQL_CODE_TYPE=[NATIVE|INTERPRETED]

AttheSESSIONlevel:

ALTERSESSIONSETPLSQL_CODE_TYPE=[NATIVE|INTERPRETED]

Alternatively,youcanalsocompileaparticularPL/SQLprogramunitinthenativeorinterpretedmethodbyrecompilinganobjectusingtheALTER<objecttype>statement.Forexample,thefollowingscriptwillrecompileaprocedurewithanewvalueforPLSQL_CODE_TYPE,butreusingtheexistingcompilationparameters:

ALTERPROCEDURE<procedurename>COMPILEPLSQL_CODE_TYPE=NATIVEREUSE

SETTINGS

/

ThePL/SQLprogramunitsretaintheircompilationmodesettingunlesstheyarerecompiledinadifferentcompilationmode.

QueryingthecompilationsettingsThecompilationmodeofanobjectcanbequeriedfromthedatadictionaryview:[USER|DBA|ALL]_PLSQL_OBJECT_SETTINGS.Thisdictionaryviewcontainsthecompilationsettingsforstandaloneprogramunits,packagespecification,packagebody,andpackagedsubprograms:

/*DescribethestructureofUSER_PLSQL_OBJECT_SETTINGS*/

SQL>DESCUSER_PLSQL_OBJECT_SETTINGS

NameNull?Type

--------------------------------------------------------

NAMENOTNULLVARCHAR2(30)

TYPEVARCHAR2(12)

PLSQL_OPTIMIZE_LEVELNUMBER

PLSQL_CODE_TYPEVARCHAR2(4000)

PLSQL_DEBUGVARCHAR2(4000)

PLSQL_WARNINGSVARCHAR2(4000)

NLS_LENGTH_SEMANTICSVARCHAR2(4000)

PLSQL_CCFLAGSVARCHAR2(4000)

PLSCOPE_SETTINGSVARCHAR2(4000)

ORIGIN_CON_IDNUMBER

CompilingaprogramunitfornativeorinterpretedcompilationInthissection,let’scheckhowaPL/SQLprogramunitcanbecompiledindifferentcompilationmodesattheobjectlevel.

1. Showthecompilationmodeofthesession:

/*Connectassysdba*/


/*DisplaycurrentsettingofparameterPLSQL_CODE_TYPE*/

SELECTname,

value

FROMv$parameter

WHEREname='plsql_code_type'

/

NAMEVALUE

----------------------------------------

plsql_code_typeINTERPRETED

2. Createastandalonefunction,whichcurrentlygetscompiledintheINTERPRETEDmode:

/*Createafunction*/

CREATEORREPLACEFUNCTIONf_get_caps(p_nameVARCHAR2)

RETURNVARCHAR2

IS

BEGIN

RETURNUPPER(p_name);

END;

/

Functioncreated.

3. VerifythecompilationmodeoftheF_GET_CAPSfunction:

/*QuerythecompilationsettingsforthefunctionF_GET_CAPS*/

SELECTname,

type,

plsql_code_type,

plsql_optimize_levelOPTIMIZE

FROMUSER_PLSQL_OBJECT_SETTINGS

WHEREname='F_GET_CAPS'

/

NAMETYPEPLSQL_CODE_TYPEOPTIMIZE

-------------------------------------------------

F_GET_CAPSFUNCTIONINTERPRETED2

4. Recompilethefunctionusingnativemode:

/*Explicitlycompilethefunction*/

ALTERFUNCTIONf_get_capsCOMPILEPLSQL_CODE_TYPE=NATIVE

/

Functionaltered.

5. ConfirmthechangeinthecompilationmodeoftheF_GET_CAPSfunction:

/*QuerythecompilationsettingsforthefunctionF_GET_CAPS*/

SELECTname,

type,

plsql_code_type,

plsql_optimize_levelOPTIMIZE

FROMUSER_PLSQL_OBJECT_SETTINGS

WHEREname='F_GET_CAPS'

/

NAMETYPEPLSQL_CODE_TYPEOPTIMIZE

----------------------------------------------

F_GET_CAPSFUNCTIONNATIVE2

6. YoucanalsoverifythegenerationofasharedlibraryfortheF_GET_CAPSfunctionbyqueryingtheNCOMP_DLL$dictionaryview.ThelibraryisstoredasaBLOBintheNCOMP_DLL$view:

connectsys/systemassysdba

SELECTobject_name,

dllname

FROMncomp_dll$,dba_objects

WHEREobj#=object_id

ANDowner='SCOTT'

/

OBJECT_NAMEDLLNAME

--------------------------------------------------------

F_GET_CAPS465F4745545F434150535F5F53434F54545F5F465F5F3934303837

Thelibraryisautomaticallydeletedfromthedictionaryiftheobjectisrecompiledwithadifferentcompilationmode.

RecompilingadatabaseforaPL/SQLnativeorinterpretedcompilationYoucancompileallthePL/SQLprogramunitsinadatabasefrominterpretedtonativecompilationmodeandviceversa.OracleenablesthebulkcompilationofthePL/SQLprogramunitsthroughinbuiltscripts:dbmsupnv.sqlanddbmsupgin.sql.Thedbmsupgnv.sqlscriptcompilesalltheprogramunitsusingnativecompilationmodewhiledbmsupgin.sqlcompilesalltheprogramunitsininterpretedmode.Thefollowingpointsshouldbeconsideredduringtheplanningstage:

Choosetherightcompilationmode—theselectionoftheappropriatecompilationmodeisthekeytoensurebettercodeperformance.SYSDBAorauserwithDBAprivilegescanruntherecompilationprocedure.IftheuserisprotectedthroughtheOracleDatabaseVaultoption,theusermustbegrantedtheDV_PATCH_ADMINrole.Objecttypespecificationscannotbecompiledinnativecompilationmode.SkipthePL/SQLpackagespecificationswithoutanexecutablesectionfromnativecompilation.YoucannotexcludeanyPL/SQLprogramunitwhilecompilinganentiredatabaseforinterpretedcompilation.

Thefollowingstepsshowhowtocompileadatabasefornativeorinterpretedcompilationmode:

1. Shutdownthedatabase—youmustshutdowntheOracleDatabaseandtheTNSlistener.Ensurethatallconnectionstothedatabasefromtheapplicationtierareterminated.

2. SetPLSQL_CODE_TYPEasNATIVEorINTERPRETEDintheparameterfile.Ifyouareusingaserverparameterfile(spfile),youcanmodifytheparametervaluebeforeadatabaseisshutdown,orafterthedatabaseisstarted.Thedbmsupgnv.sqlscriptalsosetsPLSQL_CODE_TYPEbeforecompilingthePL/SQLprogramunits:

/*Alterthesystemtosetthenewcompilationmode*/

SQL>ALTERSYSTEMSETPLSQL_CODE_TYPE=NATIVESCOPE=SPFILE

/

Systemaltered.

3. VerifyandsetPLSQL_OPTIMIZE_LEVELas2(orhigher).4. Startthedatabaseintheupgrademode:

SQL>connectsys/oracleassysdba

Connectedtoanidleinstance.

/*Startupinupgrademode*/

SQL>startupupgrade

ORACLEinstancestarted….

...

Databasemounted.

Databaseopened.

IfyouareworkinginanOracleDatabase12cMultitenantarchitecture,youhavetoopenthepluggabledatabaseintheUPGRADEandRESTRICTEDmode:

ALTERPLUGGABLEDATABASE<pdbname>OPENUPGRADERESTRICTED

/

5. ConnectedastheSYSuser,executethedbmsupgnv.sqlscript:

/*Executetherecompilationscript*/

SQL>@ORACLE_HOME/rdbms/admin/dbmsupgnv.sql…

...

#######################################################################

#######################################################################

dbmsupgnv.sqlcompletedsuccessfully.AllPL/SQLprocedures,

functions,typebodies,triggers,andtypebodiesobjectsinthe

databasehavebeeninvalidatedandtheirsettingssettonative.

Shutdownandrestartthedatabaseinnormalmodeand

runutlrp.sqltorecompileinvalidobjects.

#######################################################################

#######################################################################

Thedbmsupgnv.sqlanddbmsupgin.sqlscriptscreateaPL/SQLpackagesys.dbmsncdbwithtwosubprograms:SETUP_FOR_NATIVE_COMPILEandSETUP_FOR_INTERPRETED_COMPILE.Thedbmsupgnv.sqlinvolvesSETUP_FOR_NATIVE_COMPILEwithausersuppliedinput.TheinputshouldbeTRUEtocompileallfunctions,procedures,packagebodies,triggers,andtypebodies.IftheinputisFALSE,packageandobjecttypespecificationsarealsoincludedintheprocess.IfthePL/SQLpackagespecificationscontainanexecutablesection,youshouldprovidetheinputasFALSE.

ThescriptmodifiesthecompilationofallthePL/SQLprogramstonativebutinvalidatesthematthesametime.

6. ShutdownandrestartthedatabaseintheNORMALmode:

/*Shutdownandstartupthedatabase*/

SQL>shutdownimmediate

Databaseclosed.

Databasedismounted.

ORACLEinstanceshutdown.

SQL>startup

ORACLEinstancestarted….

...

Databasemounted.

Databaseopened.

7. Executetheutlrp.sqlscripttorecompiletheinvalidatedobjects.Althoughtheobjectsthathavebeeninvalidatedgetautomaticallyrecompiledwhenevertheyaresubsequentlyinvoked,itisrecommendedthatyoucompileandrevalidatetheobjects

toreducerecompilationlatencies.

TipItisrecommendedthatyourunutlrp.sqlinarestrictedsession.Anyconnectionrequestfromtheapplicationservicesoradatabasesessionmayleadtodeadlocks.

SQL>ALTERSYSTEMENABLERESTRICTEDSESSION

/

Systemaltered.

SQL>@ORACLE_HOME\rdbms\admin\utlrp.sql

Thescriptrecompilesalltheprogramunitsthathaveadefaultcompilationmode.Youcanrerunthescriptanynumberoftimestorecompiletheinvalidatedobjects.TherecompilationoperationcanbeoptimizedthroughparallelizationwhereinthedegreeofparallelismisselectedbasedonCPU_COUNTandPARALLEL_THREADS_PER_CPU.

Fortroubleshootinganddiagnosis,youcanusethefollowingqueries:

Querytheinvalidobjects:

SELECTo.OWNER,

o.OBJECT_NAME,

o.OBJECT_TYPE

FROMDBA_OBJECTSo,DBA_PLSQL_OBJECT_SETTINGSs

WHEREo.OBJECT_NAME=s.NAME

ANDo.STATUS='INVALID'

/

QuerythecountofthePL/SQLprogramsineachcompilationmode:

SELECTTYPE,

PLSQL_CODE_TYPE,

COUNT(*)

FROMDBA_PLSQL_OBJECT_SETTINGS

WHEREPLSQL_CODE_TYPEISNOTNULL

GROUPBYTYPE,PLSQL_CODE_TYPE

ORDERBYTYPE,PLSQL_CODE_TYPE

/

NoteThePL/SQLobjectswithNULLplsql_code_typeareOracle’sinternalobjects.

QuerythenumberofthePL/SQLobjectsthatarecompiledsofarusingutlrp.sql:

SELECTCOUNT(*)FROMUTL_RECOMP_COMPILED

/

8. Disabletherestrictedsession:

SQL>ALTERSYSTEMDISABLERESTRICTEDSESSION

/

Systemaltered.

Ifyouwanttorollbackthecompilationmodetointerpreted,youcanfollowthesamesteps,andreplacedbmsupgnv.sqlwiththedbmsupgin.sqlscript.

TuningPL/SQLcodeWehavejustdiscussedtwokeyfeaturesintheperformancemanagementspace.ThePL/SQLcodeoptimizationandcompilationcansignificantlyimproveruntimeperformance.Apartfromthecodeoptimizationtechniques,thereareseveralefficientcodingpracticesthatmayimpactoverallPL/SQLperformance.PL/SQLperformancemanagementisoftenregardedaslesstedious,whencomparedtothedatabasetuningexercisebecausetheareaofoperationisaprogramunitanddoesn’trequiretheinstancetoberestarted.Inthissection,wewilldiscusssomeoftheselectivebutkeyfeaturestoimprovePL/SQLcodingpracticesforbetterperformance.

BuildsecureapplicationsusingbindvariablesItishighlyencouragedtousebindvariablesinSQLstatementswhilebuildingrobustdatabaseapplications.BindvariablesreducetheparsingoverheadbyenablinganSQLstatementtobeexecutedusingitsalreadyparsedimagestoredinthesharedSQLareaofthedatabasememory.

EverySQLstatementexecutedbytheSQLengineisparsed,optimized,andexecuted.OnlyaftertheSQLstatementisexecutedistheresultfetchedanddisplayedtotheuser.TheSQLexecutionstepsarebrieflydescribed,asfollows:

GenerateahashvaluefortheSQLstatement.Lookforamatchinghashvalueofcachedcursorsinthesharedpool.Ifthematchisnotfound,Oraclecontinueswiththestatementparsingandoptimizationstages.Thisishardparsing.ItisaCPU-intensiveoperationandinvolvescontentionforlatchesinthesharedSQLarea.Ifthematchisfound,reusethecursorandreduceparsingtoaprivilegecheck.Thisisasoftparse.Thereafter,withoutneedingfurtheroptimization,theexplainplanisretrievedfromthelibrarycache,andtheSQLqueryisexecuted.

NoteOracleDatabase12cintroducedadaptivequeryoptimization,whichallowstheoptimizertore-optimizetheexistingexplainplansuponsubsequentexecutionsofanSQLquery.

Theresultsetisfetched.

Inanenterpriseapplication,manySELECTstatementsortransactionalstatements(INSERT,UPDATE,orDELETE)aresimilarinstructurebuttheyrunwithdifferentpredicatevalues.ThehashesfortwoofthesameSQLstatementswithdifferentvalueswillneverbethesame,thusresultinginahardparse.Ahardparse,beinganon-scalableexpensiveoperation,degradestheapplicationperformance.Theonlywaytogetridoftheproblemistoencouragesoftparsingbymaximizingtheuseofcachedcursorsandassociatedexplainplans.

Theuseofbindvariablespromotessoftparsing.Abindvariableisasubstitutionvariablethatactsasaplaceholderfortheliteralvalues.BindvariablesenableanSQLstatementtoappearthesameevenaftermultiplerunswithdifferentinputvalues.ThisreduceshardparsingandtheexistingplansinthelibrarycachecanbeusedtooptimizethecurrentSQLstatements.

TipAvoidusinghard-codedliteralsinSQLqueriesandPL/SQLprograms.

Forexample,thefollowingSELECTquerywillhavethesamehashvalueforthedifferentvaluesofemployeeids:

/*SelectEMPtablewithabindvariable*/

SELECTename,

deptno,

sal

FROMemp

WHEREempno=:empid

/

OraclePL/SQLsupportstheuseofbindvariables.Allreferencestoablockvariableorprogramargumentaretreatedasabindvariable.InthecaseofadynamicSQL,eitherusingDBMS_SQLorEXECUTEIMMEDIATE,youmustusebindvariables.BindvariableshelpdynamicSQLintwoways.Firstitimprovesthecodeperformance.Secondly,itreducestheriskofSQLinjectionbycoveringthevulnerableareas.Let’sconductasmallillustrationtoseethebenefitsofbindvariablesinPL/SQL.

ThefollowingPL/SQLblockfindsthecountofdistinctobjecttypeaccessiblebytheSCOTTuser.ItexecutestheSELECTqueryusingEXECUTEIMMEDIATE.Inordertogettheaccurateresults,wewillflushthesharedpool:


ALTERSYSTEMFLUSHSHARED_POOL

/

connectscott/tiger

SETSERVEROUTON


DECLARE

/*Localblockvariables*/

l_countNUMBER;

l_stmtVARCHAR2(4000);

clock_inNUMBER;

clock_outNUMBER;

TYPEv_obj_typeisTABLEOFvarchar2(100);

l_obj_typev_obj_type:=v_obj_type('TYPE','PACKAGE','PROCEDURE',

'TABLE','SEQUENCE','OPERATOR','SYNONYM');

BEGIN


clock_in:=DBMS_UTILITY.GET_TIME();

/*FORlooptoiteratethecollections*/

FORIINl_obj_type.first..l_obj_type.last

LOOP

l_stmt:='SELECTcount(*)

FROMall_objects

WHEREobject_type='||''''||l_obj_type(i)||'''';

EXECUTEIMMEDIATEl_stmtINTOl_count;

ENDLOOP;

/*Capturetheendtime*/

clock_out:=DBMS_UTILITY.GET_TIME();

DBMS_OUTPUT.PUT_LINE('Executiontimewithoutbind

variables:'||TO_CHAR(clock_out-clock_in));

END;

/

Executiontimewithoutbindvariables:948


Now,we’llrewritetheabovePL/SQLblockusingbindvariables:


ALTERSYSTEMFLUSHSHARED_POOL

/

connectscott/tiger

SETSERVEROUTON


DECLARE

/*Localblockvariables*/

l_countNUMBER;

l_stmtVARCHAR2(4000);

clock_inNUMBER;

clock_outNUMBER;

TYPEv_obj_typeisTABLEOFvarchar2(100);

l_obj_typev_obj_type:=v_obj_type('TYPE','PACKAGE','PROCEDURE',

'TABLE','SEQUENCE','OPERATOR','SYNONYM');

BEGIN



/*FORlooptoiteratethecollection*/

FORIINl_obj_type.first..l_obj_type.last

LOOP

/*BuildtheSELECTstatementbyusingbindvariable*/

l_stmt:='SELECTcount(*)

FROMall_objects

WHEREobject_type=:p1';

/*UsedynamicSQLtoexecutetheSELECTstatement*/

EXECUTEIMMEDIATEl_stmtINTOl_countUSINGl_obj_type(i);

ENDLOOP;


DBMS_OUTPUT.PUT_LINE('Executiontimewithbind

variables:'||TO_CHAR(clock_out-clock_in));

END;

/

Executiontimewithbindvariables:121


Theblockwiththebindvariablesgetsexecutedatleast8timesfasterthantheonewhichusesliteralsintheSQLqueryinsidethePL/SQLblock.ThereasonfortheperformancegainisthesoftparsingoftheSELECTstatement.

Inthecaseoflegacyapplicationsoraccessprotectedapplications,youmightfacedifficultiesinmodifyingthecodetoincludethebindvariables.Oraclemakesthisdauntingtaskeasierbycontrollingthecursorsharingbehaviorthroughaswitch.YoucansetCURSOR_SHARINGparametertoEXACTorFORCEtosharethecursorsacrossthesessionsinadatabaseinstance.IftheparameterissettoEXACT,onlytheSQLstatementsthathaveexactlythesamestructureandparameterswillbeshared.IftheparameterissettoFORCE,thenOracleattemptstosubstitutealltheliteralsinaquerywithsystem-generatedbindvariables.Bydefault,theparametervalueissettoEXACT.Cursorsharinggreatlyimprovestheperformance.Atthesametime,forcedcursorsharinginvolvesextraeffortinsearchingforthesamecursorinthesharedpool.

NoteTheSIMILARvalueofCURSOR_SHARINGhasbeendeprecatedinOracleDatabase12c.

CallparametersbyreferenceAPL/SQLprograminvocationcanpassaparametereitherbyitsvalueorbyreference.ArgumentsintheINmodearepassedbyreference(thedefault)whiletheargumentsintheOUTandINOUTmodesarepassedbyvalue.Inthecaseofpassbyvaluemethod,theparametervaluebeforetheinvocationhastobestoredinatemporaryvariable.Thistemporaryvariableisamemoryvariableandisusedtoassignthevaluebacktotheparameter,ifthesubprogramcallendsinanunhandledexception.IfthePL/SQLprogramacceptscompositedatatypesandcomplexvariablesintheOUTandINOUTmodes,copyingandmaintainingthetemporaryvariablecancauseaperformanceoverhead,therebyslowingdowntheprogramexecution.

OraclerecommendsthatyouspecifytheNOCOPYhintforthepassbyvalueparameters.AparameterwiththepassmodeasOUTNOCOPYorINOUTNOCOPYispassedbyreference,thusavoidingtheoverheadofmaintainingatemporaryvariable.Forsimpledatavalues,whicharegenerallysmall,thegainwillbenegligible.

AvoidinganimplicitdatatypeconversionOracleconvertsthedatatypestoacompatibletypeduringtheoperationslikeassignment,predicateswithvaluecomparison,orpassingparameterstosubprograms.Thisisanimplicitactivitythatfollowsadatatypeprecedencetoconvertthedatatypes.However,itmaycauseanoverheadwhenexecutingacriticalprogram.Thefollowingarethebestpracticesthatcanreducetheimplicitdatatypeconversionintheprograms:

UnderstandthatSQLdatatypesandPL/SQLdatatypeshavedifferentinternalrepresentations.YoushouldexplicitlyconverttheSQLtypevariablestoPL/SQLtypesandthenusethoseinanexpression.Forexample,PLS_INTEGERisaPL/SQLdatatypethatusesmachinearithmetictospeedupcomputeintensiveoperations.IfNUMBERtypevariablesareusedinanexpression,Oracleuseslibraryarithmetic,andtherefore,therearenoperformancegains.Avariablegettingassignedtoatablecolumnshouldbeofthesamedatatypetoavoidanimplicitdatatypeconversion.Asabestpractice,declarethevariableswiththe%TYPEattribute.Similarly,arecordcanbedeclaredwiththe%ROWTYPEattribute.Suchvariabledeclarationsalwaysremainsynchronizedwiththedatabasecolumns,improvetheprogram’sscalability,andreducehumanerrors.Considerthefollowingdeclarations:

empnameemp.ename%type

typeemp_recisrecordofemp%rowtype;

CURSORcIS

SELECTprod_id,prod_code,prod_name

FROMproducts;

prod_recc%rowtype;

UsetheSQLconversionfunctiontoconverttheto-beassignedvariabletothetargetvariable’sdatatype.SomeoftheconversionfunctionsareTO_CHAR,TO_NUMBER,TO_DATE,TO_TIMESTAMP,CAST,andASCIISTR.PassavariableofcorrectdatatypewhileinvokingthePL/SQLprogramunitswithparameters.YoucanalsoincludeoverloadedsubprogramsinaPL/SQLpackagethatacceptstheparametersofthedifferentdatatypes.Youcaninvokethepackagedsubprogramthatbestmatchestheavailablesetofvariables.Forexample,thefollowingpackagehastwooverloadedfunctions.Youcaninvokeeitherofthetwodependingonthetypeofvariablesavailable:

CREATEORREPLACEPACKAGEpkg_sumAS

FUNCTIONp_sum_series(p_termPLS_INTEGER,p_factorPLS_INTEGER)

RETURNPLS_INTEGER;

FUNCTIONp_sum_series(p_termNUMBER,p_factorNUMBER)

RETURNNUMBER;

END;

/

UnderstandingtheNOTNULLconstraintAblockvariablecanbedeclaredNOTNULLatthetimeofthedeclaration.OracleperformsthenullabilitytesteverytimeavalueisassignedtotheNOTNULLvariable.InlargePL/SQLprogramunits,thenullabilitycheckcanbeanoverheadandimpactthePL/SQLblock’sruntimeperformance.Instead,itisadvisedtohaveanexplicitnullabilitycheckforthevariableintheexecutablesectionoftheblock.

ThefollowingPL/SQLprogramcomparestheperformanceofaNOTNULLvariableandnullablelocalvariable:

/*EnabletheSERVEROUTPUTtodisplayblockresults*/

SETSERVEROUTPUTON


DECLARE

l_nn_numNUMBERNOTNULL:=0;

l_numNUMBER:=0;

clock_inNUMBER;

clock_outNUMBER;

BEGIN



/*Starttheloop*/

FORIIN1..1000000

LOOP

l_nn_num:=l_nn_num+i;

ENDLOOP;


/*Computethetimedifferenceanddisplay*/

DBMS_OUTPUT.PUT_LINE('TimeforNOTNULL:'||TO_CHAR(clock_out-clock_in));



/*Starttheloop*/

FORIIN1..1000000

LOOP

l_num:=l_num+i;

ENDLOOP;


/*Computethetimedifferenceanddisplay*/

DBMS_OUTPUT.PUT_LINE('TimeforNULL:'||TO_CHAR(clock_out-clock_in));

END;

/

TimeforNOTNULL:111

TimeforNULL:76


IntheprecedingPL/SQLblock,thenullablevariableoutperformstheNOTNULLvariablebyoneandahalftimes.Thereasonforthisperformancegainisthereductioninthenumberofnullabilitychecks.

SelectionofanappropriatenumericdatatypeThePLS_INTEGERdatatypeisapartoftheNUMBERdatatypefamily.Mostofthenumberorintegerdatatypesaregenericonesandthereasonbehindthisistosupportcodeportability.However,PLS_INTEGERisspecificallydesignedforperformance.ItwasintroducedinOracleDatabaseRelease7tospeedupthecomputation-intensiveoperationsthroughnativemachinearithmeticinsteadoflibraryarithmetic.

ThefollowingPL/SQLblockcomparestheperformanceofthePLS_INTEGERandNUMBERvariables:


SETSERVEROUTPUTON


DECLARE

l_pls_intPLS_INTEGER:=1;

l_numNUMBER:=1;

l_factorPLS_INTEGER:=2;

clock_inNUMBER;

clock_outNUMBER;

BEGIN



/*Beginthelooptoperformamathematicalcalculation*/

FORIIN1..10000000

LOOP

/*Themathematicaloperationincrementsavariablebyone*/

l_num:=l_num+l_factor;

ENDLOOP;


/*Displaytheexecutiontimeconsumed*/

DBMS_OUTPUT.PUT_LINE('TimebyNUMBER:'||TO_CHAR(clock_out-clock_in));



/*Beginthelooptoperformamathematicalcalculation*/

FORJIN1..10000000

LOOP

/*Themathematicaloperationincrementsavariablebyone*/

l_pls_int:=l_pls_int+l_factor;

ENDLOOP;


/*Displaythetimeconsumed*/

DBMS_OUTPUT.PUT_LINE('TimebyPLS_INTEGER:'||TO_CHAR(clock_out-

clock_in));

END;

/

TimebyNUMBER:231

TimebyPLS_INTEGER:69


TheperformanceofthePLS_INTEGERvariableisatleastthreetimesbetterthanaNUMBERvariable.AnarithmeticexpressionhavingamixofthePLS_INTEGERandNUMBERtypevariableswilluselibraryarithmeticandnoperformancegainswillbeobtained.

PLS_INTEGERisa32-bitdatatypethatcanstorevaluesintherangeof-2147483648to2147483647.Itacceptsintegervaluesonly.IfafloatingvalueisassignedtoPLS_INTEGER,itisroundedtothenearestinteger.IfthePLS_INTEGERprecisionrangeisviolated,OracleraisesanORA-01426:numericoverflowexception.Toresolvesuchscenarios,Oracle11gintroducedanewsubtypeofPLS_INTEGER,whichisknownasSIMPLE_INTEGER.TheSIMPLE_INTEGERdatatypehasthesamerangeasthatofPLS_INTEGER,butinthecaseofnumericoverflows,itisautomaticallysetto-2147483648insteadofraisinganexception.AstheoverflowcheckissuppressedforSIMPLE_INTEGER,itisfasterthanPLS_INTEGER.

NoteSIMPLE_INTEGERisaNOTNULLdatatype;therefore,alllocalvariablesmustbeinitializedordefaultedtoadefinitivevalue.

ThefollowingPL/SQLanonymousblockdeclaresaSIMPLE_INTEGERvariableanddefaultsitto2147483646,thatis,thelastvalueintheprecisionrange.Intheprogrambody,thevariableisincrementedby1.Let’scheckwhathappens:


SETSERVEROUTPUTON


DECLARE

l_simpleSIMPLE_INTEGER:=2147483646;

BEGIN

/*Incrementthevariableby1*/

l_simple:=l_simple+1;

DBMS_OUTPUT.PUT_LINE('After1stincrement:'||l_simple);

/*Re-Incrementthevariableby1*/

l_simple:=l_simple+1;

DBMS_OUTPUT.PUT_LINE('After2ndincrement:'||l_simple);

EXCEPTION

WHENOTHERSTHEN

DBMS_OUTPUT.PUT_LINE('NumericOverflowexceptionoccurred');

END;

/

After1stincrement:2147483647

After2ndincrement:-2147483648


BulkprocessinginPL/SQLBulkdataprocessingisoneofthekeyfeaturesinperformancemanagement.BulkSQLisafeaturethatreducescontextswitchesbetweentheSQLandPL/SQLprocessingengines.OneofthebiggestbenefitsofPL/SQLdevelopmentisitsseamlessintegrationwiththeSQLlanguage.TheSQLstatementscandirectlyappearinthePL/SQLprogrambody.InaPL/SQLunitwiththeSQLstatementsandPL/SQLconstructs,thePL/SQLengineandSQLenginecommunicatethroughacontextswitch.ThePL/SQLengineswitchestheprogramcontexttotheSQLenginetoexecutetheSQLstatementsandgettheresult.Thefrequentback-and-forthcontextswitchingbetweentheprocessingenginescausesasevereoverheadandslowsdowntheprogramexecution.Therow-by-rowprocessingofrecordsisquiteslowcomparedtobulkprocessing.

OracleimplementsbulkoperationsthroughtheBULKCOLLECTclauseandtheFORALLstatement.TheBULKCOLLECTclauseretrievesmultiplerecordsinasinglefetchwhiletheFORALLstatementcanprocessmultipleDMLstatementsingroupsratherthanrowbyrow.Inmanyimplementations,theperformancegainsbytheuseofbulkprocessingfeatureshavebeenphenomenal.

BULKCOLLECTYoucanuseBULKCOLLECTin:

TheSELECT…INTOstatementTheRETURNINGINTOclausewiththeUPDATEorDELETEstatementTheFETCHINTOclausewithanexplicitcursor

Thebulkcollectfeaturedependslargelyoncollectionsandcanbeusedwithallthethreeformsofcollections,thatis,associativearrays,nestedtables,andvarrays.Multiplerecordscanbefetchedintoacollectioninasinglefetch.Thisreducesthenumberofthecontextswitchesbetweenthetwoprocessingengines.Duringthefetchoperation,thecollectionvariablesgetdenselypopulated.Inthecaseofnorowsbeingfetched,thecollectionsareleftemptyresultinginanemptycollection.

NoteBulkoperationsareaCPU-intensiveoperation.Theycannotbeparallelized.

UntilOracleDatabase9i,BULKCOLLECTcouldbeusedonlywithstaticSQLstatements,butstartingwithOracleDatabase10g,itcanbeusedindynamicSQLstatementstoo.

TheCREATETABLEscriptcreatesthetesttablewiththesampledatafromtheALL_OBJECTSdictionaryviewtobeusedinthisillustration.TheALL_OBJECTSdictionaryviewcontainsdetailsoftheschemaobjects.Duringourillustration,wewillworkwiththeobjectid,objecttype,andobjectnamecolumnsofthetable:

CREATETABLElocal_objectsAS

SELECT*FROMall_objects

/

/*Querytherecordcount*/

SELECTCOUNT(*)

FROMlocal_objects

/

COUNT(*)

----------

73673

ThefollowingPL/SQLblockopensacursor,fetchesrowbyrow,andcountsthenumberofproceduresthatcanbeaccessedbytheSCOTTuser:

SETSERVEROUTPUTON


DECLARE

/*LocalPL/SQLvariables*/

obj_idlocal_objects.object_id%TYPE;

obj_typelocal_objects.object_type%TYPE;

obj_namelocal_objects.object_name%TYPE;

counterNUMBER;

clock_inNUMBER;

clock_outNUMBER;

/*Cursortofetchtheobjectdetails*/

CURSORcIS

SELECTobject_id,object_type,object_name

FROMlocal_objects;

BEGIN



OPENc;

LOOP

FETCHcINTOobj_id,obj_type,obj_name;

EXITWHENc%NOTFOUND;

/*Countthenumberofproceduresinthetesttable*/

IFobj_type='PROCEDURE'THEN

counter:=counter+1;

ENDIF;

ENDLOOP;

CLOSEc;



DBMS_OUTPUT.PUT_LINE('Timetakeninrowfetch:'||to_char(clock_out-

clock_in));

END;

/

Timetakeninrowfetch:369


Therow-by-rowfetchtook369hsectogetexecuted.Therewere73673contextswitchesmadebetweenthePL/SQLandSQLengines.Now,let’sapplythebulkfetchtechniquestotheprecedingblock,andchecktheperformancegains:

SETSERVEROUTPUTON


DECLARE

/*Declarethelocalrecordandtablecollection*/

TYPEobj_recISRECORD

(obj_idlocal_objects.object_id%TYPE,

obj_typelocal_objects.object_TYPE%TYPE,

obj_namelocal_objects.object_name%TYPE);

TYPEobj_tabISTABLEOFobj_rec;

t_all_objsobj_tab;

counterNUMBER;

clock_inNUMBER;

clock_outNUMBER;

BEGIN



/*Selectquerytobulkfetchmulti-recordsetinnestedtable

collection*/

SELECTobject_id,object_TYPE,object_name

BULKCOLLECTINTOt_all_objs

FROMlocal_objects;

/*Loopthroughthecollectiontocountnumberofprocedures*/

FORIINt_all_objs.FIRST..t_all_objs.LAST

LOOP

IF(t_all_objs(i).obj_type='PROCEDURE')THEN

counter:=counter+1;

ENDIF;

ENDLOOP;



DBMS_OUTPUT.PUT_LINE('Timetakeninbulkfetch:'||to_char(clock_out-

clock_in));

END;

/

Timetakeninbulkfetch:35


Well,thebulkSQLisaround10timesfasterthantheusualfetchoperation.ThereasonisthattherewasonlyonecontextswitchmadebetweentheSQLandPL/SQLengines.Notethatthenestedtablecollectionvariableisnotrequiredtobeinitializedforbulkoperations.

NoteTheBULKCOLLECToperationdoesnotraisetheNO_DATA_FOUNDexception.

BulkprocessingisaCPU-intensiveoperation,andfetchingintoacollectionconsumesyoursessionmemory.Ifthebulkcollectfetchesalargenumberofrowsandthesessionmemoryisnotlargeenough,youmightexperienceahungsessionoranabnormaltermination.Toresolvesuchcases,OracleprovidestheLIMITclausetocontrolthenumberofrecordsretrievedinasinglefetchoperation.ThefollowingPL/SQLblockusestheLIMITclausetocontrolthenumberofrecordsfetchedduringtheFETCHoperation:

SETSERVEROUTPUTON


DECLARE

/*Localblockvariables-objecttyperecordandnestedtable*/

TYPEobj_recISRECORD




TYPEobj_tabistableofobj_rec;

t_all_objsobj_tab;

counterNUMBER;

p_rec_limitNUMBER:=100;

clock_inNUMBER;

clock_outNUMBER;

/*CursortofetchobjectdetailsfromLOCAL_OBJECTS*/

CURSORCIS


FROMlocal_objects;

BEGIN



/*Openthecursor*/

OPENc;

LOOP

/*Bulkfetchtherecordsbyspecifyingthelimit*/

FETCHcBULKCOLLECTINTOt_all_objsLIMITp_rec_limit;

EXITWHENc%NOTFOUND;

/*FORlooptocounttheprocedures*/


LOOP

IF(t_all_objs(i).obj_type='PROCEDURE')THEN

counter:=counter+1;

ENDIF;

ENDLOOP;

t_all_objs.DELETE;

ENDLOOP;

CLOSEc;


DBMS_OUTPUT.PUT_LINE('Timetakenincontrolledfetch:'||to_char

(clock_out-clock_in));

END;

/

Timetakenincontrolledfetch:94


Acontrolledbulkoperation,limitedto100recordsperbulkfetch,took94hsectogetexecuted,whichisstill4timesbetterthantherow-by-rowfetchoperation.Thistimetheprogrammakes737contextswitchesbetweenthePL/SQLandSQLengines.

FORALLMorethaniterative,FORALLisadeclarativestatement.TheDMLstatementsspecifiedinFORALLaregeneratedonce,buttheysendinbulktotheSQLengineforprocessing,thusmakingonlyasinglecontextswitch.TherecanbeonlyoneDMLstatementinFORALLthatcanbeINSERT,UPDATE,orDELETE,ortheFORALLstatementcanbeused,asperthefollowingsyntax:

FORALLindexIN

[

lower_bound…upper_bound|

INDICESOFindexing_collection|

VALUESOFindexing_collection

]

[SAVEEXCEPTIONS]

[DMLstatement]

IftheDMLstatementscontainbindvariables,thebulkSQLbindsallthestatementsinasinglestep.Thisisknownasbulkbinding.

Let’ssetuptheenvironmentforourperformancetest.TheperformancetestwillcomparetheexecutiontimeofaFORloopversusaFORALLstatement:

/*CreatetableT1withbasicobjectcolumns*/

CREATETABLET1

AS


FROMall_objects

WHERE1=2

/

/*CreatetableT2withbasicobjectcolumns*/

CREATETABLET2

AS


FROMall_objects

WHERE1=2

/

ThefollowingPL/SQLblockbulkcollectsthedatafromtheLOCAL_OBJECTStable,createsaninterimcollection(associativearray)foronlythesynonyminformation,andinsertsitintotwodifferenttables.Forverification,wewillquerytherecordsinsertedinboththetables:

SETSERVEROUTPUTON


DECLARE

/*Localblockvariables-objecttyperecordandnestedtablecollection*/

TYPEobj_recISRECORD





TYPEsyn_tabISTABLEOFobj_recindexbypls_integer;

t_all_objsobj_tab;

t_all_synsyn_tab;

counterNUMBER:=1;

clock_inNUMBER;

clock_outNUMBER;

BEGIN

/*BULKCOLLECTthedatafromLOCAL_OBJECTSinnestedtablecollection*/



FROMlocal_objects;


LOOP

/*Captureallsynonymsinanothercollection*/

IF(t_all_objs(i).obj_type='SYNONYM')THEN

t_all_syn(t_all_syn.count+1):=t_all_objs(i);

ENDIF;

ENDLOOP;


/*FORlooptoinsertthedataintableT1*/

FORIINt_all_syn.first..t_all_syn.last

LOOP

INSERTINTOt1VALUESt_all_syn(i);

ENDLOOP;


DBMS_OUTPUT.PUT_LINE('TimetakenbyFORloop:'||to_char(clock_out-

clock_in));


/*FORALLstatementtoinsertthedataintableT2*/

FORALLIINt_all_syn.first..t_all_syn.last



DBMS_OUTPUT.PUT_LINE('TimetakenbyFORALL:'||to_char(clock_out-

clock_in));

END;

/

TimetakenbyFORloop:1637

TimetakenbyFORALL:29


/*QuerytherecordcountinT2*/

SQL>SELECTCOUNT(*)FROMt2

/

COUNT(*)

----------

37031

/*QuerytherecordcountinT1*/

SQL>SELECTCOUNT(*)FROMt1

/

COUNT(*)

----------

37031

Thisisphenomenal!TheFORALLstatementinsertedmorethan37000recordsinlessthanasecond,whereastheFORLOOPstatementtook16sectoinsertthesamenumberofrecords.Thereasonisagainthecontextswitchbetweentheprocessingengines;oneswitchagainst37000contextswitches.

Inthecaseofasparsecollection,useINDICESOForVALUESOFintheFORALLstatement.Itwilluseonlythoseindexesofthecollectionthatholdavalue.ThefollowingPL/SQLblockusestheFORALLstatementtoinsertasparsecollectionintotheT2table.Tosparsetheinterimcollection,thesynonymsstartingwithSYS%aredeletedfromit:

/*TruncatetableT2forthecurrenttest*/

TRUNCATETABLEt2

/

SETSERVEROUTPUTON


DECLARE


TYPEobj_recISRECORD






t_all_objsobj_tab;

t_all_synsyn_tab;

counterNUMBER:=1;

clock_inNUMBER;

clock_outNUMBER;

BEGIN

/*BULKCOLLECTthedatafromLOCAL_OBJECTSinnestedtablecollection*/



FROMlocal_objects;

/*FORlooptocollectallsynonymsinnestedtablecollection*/


LOOP



ENDIF;

ENDLOOP;

/*DeleteallthesynonymswhosenamesstartswithSYS%*/

FORIin1..t_all_syn.count

LOOP

IFt_all_syn(i).obj_namelike'SYS%'THEN

t_all_syn.delete(i);

ENDif;

ENDLOOP;


/*InsertthesparsecollectionusingINDICESofclause*/

FORALLIININDICESOFt_all_syn



DBMS_OUTPUT.PUT_LINE('TimetakenbyFORALL:'||to_char(clock_out-

clock_in));

END;

/

TimetakenbyFORALL:30


/*QuerytherecordcountintableT2*/

SQL>selectcount(*)fromt2;

COUNT(*)

----------

37025

ThereweresixsynonymsstartingwithSYS%thatwerenotinsertedinthisrun.Ifyouhadn’tusedtheINDICESOFclause,theblockwouldhaveterminatedwiththeORA-22160:

elementatindex[3]doesnotexistexception.

FORALLandexceptionhandling

FORALLisspecificallydesignedforbulktransactions.Anyfaultytransactioninthebulkoperationmaycausetheentirebulkoperationtoabortwithanexception,therebyrollingbackallthechangesmadebytheearliertransactionsofthesameDMLstatement.OraclegracefullydealswithsuchscenariosbysavingtheerroneousrecordandexceptioninformationseparatelyandbycontinuingtheDMLexecution.TherearetwowaystohandleanexceptionintheFORALLstatement:

1. AborttheFORALLexecutionbutcommitthechangesmadebytheearliertransactions:TraditionalexceptionhandlingbutwithaCOMMITintheexceptionhandler.Forexample,thefollowingexceptionhandlewillcommitthetransactionsthathavebeenexecutedalready:

EXCEPTION

WHENOTHERSTHEN

DBMS_OUTPUT.PUT_LINE(SQLERRM);

COMMIT;

RAISE;

2. ContinuetheFORALLexecutionandsavethefailedtransactions:UseSAVEEXCEPTIONSwiththeFORALLstatement.Thefeatureisknownasbulkexceptionhandling.WithSAVEEXCEPTION,OraclestoresthefaultyDMLdetailsinthebulkexceptionloggerknownasSQL%BULK_EXCEPTIONS.AftertheFORALLexecutionisover,databaseadministratorscanlookintotheexceptionlogandtroubleshootthedefectiverecords.ThedefectiverecordsareskippedandloggedundertheSQL%BULK_EXCEPTIONSpseudocolumn.Forexample,ifFORALLgenerated5000updatestatements,outofwhich13werefailedtransactions,4987recordswillstillbeupdated.The13defectivetransactionswillbeloggedintheSQL%BULK_EXCEPTIONSarraystructurewiththecursorindex.

The%BULK_EXCEPTIONSattributemaintainstwofields—ERROR_INDEXandERROR_CODE.ERROR_INDEXstoresthedefectrecordindexwheretheexceptionwasraised,whileERROR_CODErecordstheexceptionmessage.%BULK_EXCEPTIONS.COUNTstoresthecountofexceptionsraisedduringtheexecutionoftheFORALLstatement.NotethatthestandarderrorcodecapturedbytheERROR_CODEattributeisnotprefixedwiththenegative(-)sign.Therefore,inordertofetchitsequivalenterrormessage,passtheerrorcodemultipliedby-1totheSQLERRMfunction.

Inthelastillustration,weexplicitlyremovedthevaluesstartingwithSYS%.Forthecurrentdemonstration,wewilladdacheckconstraintontheOBJECT_NAMEcolumnoftheT2table.Thefollowingscriptaddsthecheckconstraint:

/*TruncatetableT2forcurrenttest*/

TRUNCATETABLEt2

/

/*AddcheckconstraintonOBJECT_NAME*/

ALTERTABLEt2

ADDCONSTRAINTt2_obj_nameCHECK(object_nameNOTLIKE'SYS%')

/

Now,wewillrunthefollowingPL/SQLblocktoinsertthedensecollectionintotheT2table.AsSAVEEXCEPTIONShasbeenspecifiedalongwiththeFORALLstatement,ifthereareanyexceptionswhileloading,theywillbesavedinthebulkexceptionlog:

SETSERVEROUTPUTON


DECLARE


TYPEobj_recISRECORD






t_all_objsobj_tab;

t_all_synsyn_tab;

counterNUMBER:=1;

clock_inNUMBER;

clock_outNUMBER;

/*Declareuserdefinedexceptionforerrornumber-24381*/

bulk_errorsEXCEPTION;

PRAGMAEXCEPTION_INIT(bulk_errors,-24381);

BEGIN

/*Bulkcollectobjectdetailsinnestedtablecollectionvariable*/



FROMlocal_objects;

/*Filterallsynonymsandcaptureinanothercollection*/


LOOP



ENDIF;

ENDLOOP;

/*FORALLstatementtoinserttherecordsintableT2*/

FORALLIIN1..t_all_syn.count

/*Savefaultyrecordsinbulkcollectioncursorattributes*/

SAVEEXCEPTIONS

insertintot2valuest_all_syn(i);

EXCEPTION

/*Exceptionhandlertoquerythefailedtransactions*/

WHENBULK_ERRORSTHEN

FORJIN1..SQL%BULK_EXCEPTIONS.COUNT

LOOP

DBMS_OUTPUT.PUT_LINE('----------------------------------------');

DBMS_OUTPUT.PUT_LINE('Errorin

INSERT:'||SQL%BULK_EXCEPTIONS(J).ERROR_INDEX);

DBMS_OUTPUT.PUT_LINE('ErrorMessageis:'||sqlerrm('-

'||SQL%BULK_EXCEPTIONS(J).ERROR_CODE));

ENDLOOP;

END;

/

----------------------------------------

ErrorinINSERT:3

ErrorMessageis:ORA-02290:checkconstraint(.)violated

----------------------------------------

ErrorinINSERT:2089


----------------------------------------

ErrorinINSERT:2091


----------------------------------------

ErrorinINSERT:2093


----------------------------------------

ErrorinINSERT:2094


----------------------------------------

ErrorinINSERT:3545



SQL>selectcount(*)fromt2;

COUNT(*)

----------

37025

ThetransactionsthatfailedtogetexecutedduetothecheckconstraintviolationweresavedintheBULK_EXCEPTIONScursorattribute.Besidesthesesixrecords,alltheotherdatawasinserted,andthiscanbeconfirmedbyaSELECTqueryonthetable.

SummaryInthischapter,wehavediscussedthefeaturesthatcantuneyourPL/SQLcodetorunfaster.WehavealsoseenhowcodecompilationandoptimizationcanspeeduptheperformanceofthePL/SQLprograms.Inthelaterhalf,wediscussedthePL/SQLtuningfeaturesindetailwiththehelpofdemonstrations.

Inthenextchapter,wewillfocusononeofthemajornewfeaturesintroducedinOracleDatabase11g.Thefeatureisknownasresultcachingthatisprimarilybuilttoacceleratetheperformanceofqueriesthatarerepeatedlyexecuted.Wewilldiscussthedifferentflavorsofresultcachinginthenextchapter.

PracticeexerciseIdentifythenatureoftheprogramthatisbestsuitedfortheinterpretedmodeofcompilation.

1. TheprogramunitcontainsmultipleSQLstatements.2. Theprogramunithasjustbeendevelopedandisinthedebugstage.3. Theprogramunitusescollectionsandbulkbindstatements.4. Theprogramunitisintheproductionphase.

ChoosethecorrectstatementsabouttherealnativecompilationmodeinOracle11g.

1. ThecompilationmethodusestheCcompilertoconverttheprogramintoanequivalentCcode.

2. ThecompilationmethodmountsthesharedlibrariesthroughthePLSQL_NATIVE_LIBRARY_DIRandPLSQL_NATIVE_LIBRARY_SUBDIR_COUNTparameters.

3. ThecompilationdoesnotusetheCcompilerbutconvertstheprogramunitdirectlytotheMcode.

4. TherealnativecompilationissupportedforRACenvironmentsandparticipatesinthebackuprecoveryprocesses.

DeterminethebehaviorofthePLSQL_OPTIMIZE_LEVELoptimizerwhenithasbeensetto3.

1. Theoptimizerwouldinlinetheprogramsthatarenecessary.2. Theoptimizerwouldinlinealltheprogramsirrespectiveofthegains.3. TheoptimizerwouldinlineonlythosesubprogramswhichhavePRAGMAINLINE.4. Thesettinghasnoeffectontheinliningofthesubprograms.

ChoosethecorrectstatementsaboutthecompilationsettinginOracle.

1. FromOracle11g,thedefaultvalueofPLSQL_CODE_TYPEisNATIVE.2. Anobjectcanberecompiledinacompilationmodethatisdifferentfromthe

currentdatabasesetting.3. Duringthedatabaseupgrade,PLSQL_CODE_TYPEmustbemodifiedinthepfile

instance.4. Inrealnativecompilation,thelibrariesgeneratedarestoredinasecuredfile

system.

IdentifythetuningtipsinthefollowingPL/SQLblock:

DECLARE

CURSORCIS

SELECTENAME,SAL,COMM

FROMEMPLOYEES;

L_COMMNUMBER;

BEGIN

FORIINC

LOOP

L_COMM:=I.SAL+((I.COMM/100)*(I.SAL*12));

DBMS_OUTPUT.PUT_LINE(I.ENAME||'earns'||L_COMM||'as

commission');

ENDLOOP;

END;

/

1. UseBULKCOLLECTtoselecttheemployeedata.2. DeclareL_COMMasNOTNULL.3. UsePLS_INTEGERforL_COMM.4. Notuningisrequired.

WhichofthesestatementsaretrueaboutinlininginPL/SQLsubprograms?

1. Theoptimizercaninlineonlythestandalonestoredfunctions.2. Theoptimizercaninlineonlythelocallydeclaredsubprograms.3. Inliningisalwaysusefulintheperformanceirrespectiveofthesizeofthe

subprogram.4. Theoptimizercannotidentifyanysubprogramforinliningwhentheoptimizer

levelissetat0.

Examinethefollowingcodeanddeterminetheoutput:

DECLARE

FUNCTIONF_ADD(P_NUMNUMBER)

RETURNNUMBER

IS

BEGIN

RETURNP_NUM+10;

END;

BEGIN

FORIIN122..382

LOOP

PRAGMAINLINE(F_ADD,'YES');

L_SUM:=L_SUM+F_ADD(I);

ENDLOOP;

END;

/

1. PLSQL_OPTIMIZE_LEVELissetto2.2. TheF_ADDlocalfunctionwouldnotbecalledinlineunless

PLSQL_OPTIMIZE_LEVELissetto3.3. TheF_ADDlocalfunctionmaybecalledinlinebecausePLSQL_OPTIMIZE_LEVEL

issetto2.4. TheF_ADDlocalfunctionwouldbecalledinlinebecausePRAGMAINLINEmarksit

forinline.5. Inliningcannotbedoneforlocallydeclaredsubprograms.

ThelibrariesgeneratedfromrealnativecompilationarestoredintheSYSAUXtablespace.

1. True2. False

SuggestthetuningconsiderationsinthefollowingPL/SQLblock:

DECLARE

L_SUMNATURALN:=0;

L_IDVARCHAR2(10);

BEGIN

L_ID:=256;

L_SUM:=L_ID*1.5;

END;

1. ThedatatypeofL_SUMcanbechangedtoNATURALandnullabilitycanbeverifiedintheexecutablesection.

2. L_SUMmustnotbeinitializedwithzero.3. The1.5multiplemustbeassignedtoavariable.4. L_IDmustbeofanappropriatedatatypesuchasNUMBERorPLS_INTEGER.

IdentifythecorrectstatementsaboutPRAGMAINLINE.

1. ItisthefifthpragmainOraclebesidesAUTONOMOUS_TRANSACTION,EXCEPTION_INIT,RESTRICT_REFERENCE,andSERIALLY_REUSABLE.

2. Itdoesnotworkforoverloadedfunctions.3. ItdoesnotworkforPLSQL_OPTIMIZE_LEVEL=1.4. PRAGMAINLINE(<Functionname>,'YES')ismeaninglessat

PLSQL_OPTIMIZE_LEVEL=3,becausetheoptimizerinlinesallthesubprograms.

Chapter9.ResultCacheInthelastchapter,welearnedquiteafewtechniquestotunePL/SQLcode.Bynow,youmusthavegottheideathattuningisnothinglessthananartthatcomesbypracticeandgrowswithexperience.Thebetteryouunderstandthedataandtheapplication,thehighertheprobabilityoftuningtherightareas.MostDBAsaroundtheworldarefamiliarwiththecommonlyusedtuningpracticessuchasqueryrewriting,columnindexing,instanceoptimization,materializedviews,andPL/SQLcodeoptimization.

AsOracleDatabaseprofessionals,wemightalreadybeawareofmultiplecachesresidentinthedatabaseinstancearchitecture(tonameafew:thebuffercache,librarycache,dictionarycache,orrecyclecache).Primarily,cachesaremeanttoholddatasothatthedataaccessoperationsareservedfaster.

OracleDatabase11gRelease2introducedanewcachecomponentwithinthesharedpool,knownastheServerResultCache,foraspecificjob.TheResultCacheenablescachingofresultsfromanSQLqueryorevenaPL/SQLfunctionintheServerResultCache.ThischapterwilldiscusstheResultCachefeatureindetail.Wewillunderstandhowtoconfiguretheresultcacheinadatabaseandwhatmakesitabrilliantfeature.Theoutlineofthechapterisasfollows:

OracleDatabase11gResultCache:

WhatisServerResultCache?ConfiguringtheServerResultCacheResultCacheversusBufferCacheResultCacheversusDatabaseIn-MemoryResultCacheversustheIn-MemoryDatabaseCache

SQLResultCachePL/SQLfunctionResultCacheOCIclientResultCacheTheDBMS_RESULT_CACHEpackageResultcacheinRealApplicationClusters

OracleDatabase11gResultCacheOracleDatabase11gofferedplentyofperformancemanagementfeatures;oneofthosewasserversideresultcaching.ResultcachingimplementsacachingmechanisminanOracleDatabase.Usingthisfeature,youcancachetheresultsofanSQLqueryoraPL/SQLfunctionwithinadesignatedareaintheSGA(SystemGlobalArea),knownasServerResultCache.

NoteTheresultcachingfeatureisavailableinOracleDatabaseEnterpriseEditiononly.

Conventionally,whenaqueryisexecutedforthefirsttime,Oraclelooksfortherequireddatablocksinthebuffercachefirst.Ifthedatablocksarealreadyinthebuffercache(becausepreviousSELECTquerieshadretrievedthem),thecurrentSQLquerygetsexecutedusingthatdata.Ifnot,OracleperformsphysicalI/Ostofetchthetabledatafromthediskintothebuffercacheandthenmovesaheadforthequeryprocessing.ThenexttimethesameSELECTquerywiththeidenticalpredicatesandinputsisre-executed,inthesameusersession—OracleperformslogicalI/Ostoreadthedatafromthebuffercacheandexecutethequery,butstillgoesthroughtheentirequeryprocessingcycle.

ResultCacheisintendedtotunethescenarioswhereaqueryisexecutedmorethanonceforthesamepredicatesandliterals.OraclestorestheresultofaqueryintheServerResultCacheduringitsfirstexecution.OnthesubsequentexecutionofanidenticalSELECTquery(withthesamepredicatesandliterals),theresultisfetcheddirectfromtheservercachedirectlywithoutre-executingthequery,therebyachievingimpressiveperformancegains.Wheredothesegainscomefrom?Well,thesegainsarecollectivelycontributedbythereductioninlogicalandphysicalI/Os,sorts,and,hence,theCPUconsumption.

Resultcachingcanbeenabledatthreelevels:

SQLqueryResultCache:ResultsfromSQLqueriescanbecachedinthedatabaseserver.PL/SQLfunctionResultCache:ResultsfromPL/SQLfunctionscanbecachedinthedatabaseserver.OCIResultCache:ResultsfromSQLqueriescanbecachedintheclientprocesscache.Withinthescopeofthechapter,wewillrestrictourdiscussiontotheSQLandPL/SQLResultCacheonly.

TheResultCachefeaturecanbringhugebenefitstowarehouseandanalyticworkloads.Databaseapplications,wherethedatadoesnotchangeoftenbutisfrequentlyselected,aretherightcandidatestoimplementresultcaching.Anotherpointtoconsideristhattheservercacheisamemorycomponent,albeitanon-persistentone.Itgetsauto-flushedwhenthedatabaseinstancecrashesorrestarts.

WhatistheServerResultCache?StartingwithOracleDatabase11g,theServerResultCacheisacomponentofdatabaseinstancememory,thatresideswithinthesharedpoolofSGA.ItisusedtostoretheresultsofSQLqueriesandPL/SQLfunctions.Itisfurtherlogicallydividedintotwosub-poolcomponentsknownasSQLqueryResultCacheandPL/SQLfunctionResultCache.TheSQLqueryResultCachestorestheresultsSQLqueriesandtheirdependencies.ThePL/SQLfunctionResultCachestoresresultsfromPL/SQLfunctions.

TheServerResultCacheispre-configuredtouseasmallportionofthesharedpool.IfthedatabaseusesAutomaticMemoryManagement(memory_target)formemorysizing,then0.25percentofmemory_targetisallocatedtotheResultCache.Inthecaseofautomaticsharedmemorymanagement(sga_target),0.5percentofsga_targetispre-allocatedtotheResultCache.Formanualsharedmemorymanagement(shared_pool_size),theResultCacheispre-allocatedwith1percentofshared_pool_size.

YoucandefineyourownServerResultCachesizeusingtheinitializationparameterRESULT_CACHE_MAX_SIZE.Theuser-suppliedvaluetotheparameterisroundedofftothenearestmultipleof32K.Ifthevalueofthisparameteriszero,theresultcachingfeatureisdisabled.

Youmustalsonotethat,beinganativepartofSGA,theServerResultCacheisaffectedbyAutomaticMemoryManagement(AMM).Inaddition,itabidesbytheregularcachefeaturessuchasdynamicsizingandtheLeastRecentlyUsed(LRU)algorithmtoflushouttheresultsets.ThefollowingfigurelocatestheserverResultCachecomponentintheOracleDatabasememoryarchitecture:

OracleDatabasememoryarchitecture

ConfiguringtheServerResultCacheInthissection,wewilllearnabouttheconfigurationoftheserver-sideresultcachefeature.TherearefourinitializationparametersthatcontroltheresultcachefeatureintheOracleDatabase:

RESULT_CACHE_MAX_SIZE:Thisparameterdeterminesifthecachingisenabledordisabledonthedatabaseserver.Ifitiszero,thecachingfeatureisdisabled.Youmustsetthisparametertoavaluegreaterthanzerotoenableresultcachingontheserver.Actually,itsetsthemaximumsizeoftheserverresultcacheinthesharedpool.OraclerecommendstorestricttheServerResultCacheupto75percentofthesharedpool.

InRACenvironments,thisparametermustbesetateachinstance.

RESULT_CACHE_MAX_RESULT:Thisparameterdefinesthesizeofasingleresultsetintheservercache.ItisexpressedasapercentagevalueofRESULT_CACHE_MAX_SIZE.Bydefault,itsvalueis5percent.RESULT_CACHE_MODE:ItdetermineswhetheranSQLqueryhastobeservedfromtheSQLqueryresultcache.Inotherwords,theparameterdecidesiftheResultCacheoperationhastobeaddedinthequeryexecutionplan.ThecachingmodecanbeMANUALorFORCE:

MANUAL(default):TheservercachestheresultsofonlytheannotatedqueriesthataremarkedwiththeRESULT_CACHEhint.FORCE:Thedatabaseenforcesacachelookupforallthequeriesandwillattempttostoretheresultsforallthequeriesthatareexecutedontheserver.However,youcanusetheNO_RESULT_CACHEhinttoskipthecachelookup.

NoteUseFORCEmodecautiouslyasitenforcescachingforallSQLqueriesandthisbehaviormayexhausttheserverresultcache.

RESULT_CACHE_REMOTE_EXPIRATION:Thisparameterdefinestheretentiontimeofaresultcachedfromaremoteobject.Itisexpressedinminutesanditsvalueiszero,bydefault.

Forexample,thefollowingALTERSYSTEMcommandsetsthesizeoftheServerResultCache:

CONNECTsys/oracleasSYSDBA

ALTERSYSTEMSETresult_cache_max_size=25MSCOPE=BOTH

/

Let’squerytheV$PARAMETERviewtoconfirmtheeffectoftheprecedingcommand.NotetheISPDB_MODIFIABLEcolumn.

SELECTname,

value,

ispdb_modifiable

FROMv$parameterWHEREnamelike'result%'/

NAMEVALUEISPDB

-----------------------------------------------

result_cache_modeMANUALTRUE

result_cache_max_size26214400FALSE

result_cache_max_result5FALSE

result_cache_remote_expiration0TRUE

Theprecedingqueryoutputshowsthat,inamultitenantcontainerdatabase(OracleDatabase12c),theServerResultCacheiselasticallysharedbyallthepluggabledatabases.TheparametersthatcanbemodifiedfromthecontextofapluggabledatabaseareRESULT_CACHE_MODEandRESULT_CACHE_REMOTE_EXPIRATION.Apluggabledatabaseadministrator(PDBA)caneitherswitchonautomaticresultcachingforthedatabaseorusethemanualmodeofcaching.Inaddition,theresultsetexpirationtimecanvaryforeachpluggabledatabaseinamultitenantcontainerdatabase.Mission-criticaldatabasesorthoseathigherservicelevelscanretaintheirresultsetsforlongerthanlow-prioritydatabases.

Whathappenswhentheresultcachegetsfull?Theleastrecentlyusedresultisautomaticallyflushedfromthecachetomakeroomfornewresults.

ResultCacheversusBufferCacheTheResultcacheandbuffercachearepartofthedatabasememoryarchitecture,butbotharemeanttoachievedifferentobjectives.TheBuffercacheisusedtostorethedatablocksofatableandtheseblocksarenotcoupledtoanSQLquery.TheResultcachestorestheendresultsandnottheblocksfromtheSQLqueriesandthusistiedtoaparticularSQLquery.TheResultcachedoesn’tworkontheconceptsofblocksorbuffers.

ResultCacheversusOracle12cDatabaseIn-MemoryTheServerResultCachestorestheresultsfromSELECTqueriesandtheseresultsaredependentontheunderlyingdatasources.ButDatabaseIn-Memoryenablesthecolumnizationofrow-formatdataandstoresitwithintheIn-MemoryColumnStoreoftheSGA.ThecolumnardataintheIn-Memorycolumnstorecanbecompressedwhileresultsintheservercachecannotbecompressed.

ResultCacheversusIn-MemoryDatabaseCacheTheIn-MemoryDatabaseCache(IMDB)isadatabaseoptionthatusesOracle’sTimesTendatabaseunderthecovers.Itisdeployedintheapplicationtiertostagebusiness-criticaldataclosertotheapplicationand,henceimprovetheresponsetime.TheapplicationconnectstotheIMDBcacheandperformstransactionsonthecacheddata;thechangesarepostedtothedatabasetierthroughthesynchronousorasynchronousmethods.Ontheotherhand,theServerResultCachefeaturestorestheresultsofSQLqueriesandPL/SQLfunctions,butnotthetabledata.However,itisdependentonthetabledataandturnsstaleiftheunderlyingdatagetsmodified.

SQLqueryResultCacheYoucanstoretheresultsofaSQLqueryintheSQLqueryresultcacheinthreeways:

Enablingautomaticresultcacheatthedatabaselevel:AutomaticSQLresultcachingisenabledbysettingtheinitializationparameterRESULT_CACHE_MODEtoFORCE,whichenforcescachingforalltheSQLstatements.However,youcanpreventspecificSQLqueriesfromexhaustingtheServerResultCachebyusingtheNO_RESULT_CACHEhint.Enablingautomaticresultcacheatthetablelevel:YoucansetRESULT_CACHEmodetoFORCEforaparticulartablesothattheresultsfromthequeriesonthistablewillbecachedinthequeryresultcache.

ALTERTABLEmy_objectsRESULT_CACHE(MODEFORCE)

/

YoucanspecifyaNO_RESULT_CACHEhinttoavoidthecachelookupoperationforaqueryusingthecacheenforcedtable,andevenrollbackthecachingmodetoMANUAL.

ManuallyannotatingselectiveSQLqueries:YoucanalsospecifyaRESULT_CACHEhintinafrequentlyexecutedSQLquerytocacheitsresults.Thisisknownasmanualresultcaching.Inthiscase,RESULT_CACHE_MODEmustbesettoMANUAL.Queriesthatscanlargevolumesofdataandreturnasmallresultaregoodcandidatesforcaching.

NoteTheRESULT_CACHEhintcanalsobeusedinsub-queriesandin-lineviews.

HowaretheresultsstoredintheSQLqueryresultcache?Wheneveraqueryexecutes,thedatabaseperformsacachelookuptosearchforaresultfrompreviousexecutionsofthesamequery.Iftheresultisfound,thecachedresultisreturnedwithoutfurtherre-executingtheSQLquery.Iftheresultisnotfound,theSQLqueryisexecutedasusualandtheresultisreturnedtotheuser.Theresultisthencachedinthequeryresultcache.

Howisitdifferentfrommaterializedviews?ResultCachingandmaterializedviewsappearsimilarinconceptasbothimprovequeryperformancebymaintainingaseparatecopyofaqueryresult,buttheyareverydifferentinimplementation.AmaterializedviewoccupiesoccupydatabasestoragetostorethedatawhiletheServerResultCacheconsumestheinstancememory.Thedatainmaterializedviewsgetsperiodicallyrefreshedbyre-executingthebasequerybuttheresultcachegetsautomaticallybuiltonthesubsequentrunoftheSQLqueryorPL/SQLfunction.Materializedviewispersistentwhiletheresultcacheisnon-persistent.

Aresultsetintheservercachecanbeusedonlyifthesamequeryisre-executed(ignoringblankspacesandindentationofthequery).Aresultsetisuniquelyidentifiedasacombinationofdependenttables,predicates,literalinputs,andtheresult.Ifthequeryusesbindvariables,Oraclestoresadistinctresultsetforeachuniquecombinationofbindvariablevalues.

LetuscreateascenariotodemonstrateSQLresultcaching.Thefollowingscriptcreatesa

tablefromtheALL_OBJECTSdictionaryviewforourcasestudy:

CONNECTscott/tiger

CREATETABLEmy_objects

ASSELECT*FROMall_objects

/

SELECTcount(*)

FROMmy_objects

/

COUNT(*)

----------

89507

ThefollowingSQLgivesthecountofobjectsbytheirobjecttypeandstatus.NoticethattheRESULT_CACHEhinthasbeenusedtoaddtheResultCacheoperatorintheexecutionplananddoacachelookup.Additionally,wearealsoaddingGATHER_PLAN_STATISTICStogatheradditionalstatisticsforthequeryexecution:

SETTIMINGON

SELECT/*+RESULT_CACHEGATHER_PLAN_STATISTICS*/

object_type,

status,

count(*)

FROMmy_objects

GROUPBYobject_type,status

ORDERBYobject_type,status

/

Elapsed:00:00:00.92

Theprecedingqueryreturns43rows.Nowletuschecktheexplainplan:

SELECT*

FROMTABLE(DBMS_XPLAN.DISPLAY_CURSOR(FORMAT=>'ALLSTATSLAST'))

/

TheexplainplanshowstheRESULTCACHEoperation,whichconfirmstheresultofthecachelookupoperation.Sincethisisthefirstexecutionofthequery,theresultiscachedinthequeryresultcachebytheID'br0p4fgjgh7jp128u0paxavkns'.TheStartscolumnshowsthatalloperationswerecarriedoutatleastonceinthecurrentexecution.Theactualrows(A-Rows)showthecountofrowsscannedduringthefulltablescanandgroupedbyrowcount.

Letusre-executethisqueryandchecktheexplainplan:


object_type,

status,

count(*)

FROMmy_objects



/

Elapsed:00:00:00.01

Notethatthesecondexecutionissignificantlyfasterthanthefirstexecution.Queryingtheexplainplan:

SELECT*

FROMTABLE(DBMS_XPLAN.DISPLAY_CURSOR(FORMAT=>'ALLSTATSLAST'))

/

TheStartscolumnshowsthattheresultisretrievedfromthequeryresultcache.ItshowszerofortheHASHGROUPBYandTABLEACCESSFULLoperations,whichmeansthattheseoperationswereignored.A-rowsvaluesarezeroastherewerenorowsscannedinthis

execution.

MonitoringtheSQLResultCacheOracleprovidesdynamicviewstoquerythecurrentstateoftheresultcache.TheseviewsareV$RESULT_CACHE_OBJECTS,V$RESULT_CACHE_STATISTICS,V$RESULT_CACHE_MEMORY,andV$RESULT_CACHE_DEPENDENCY.Beforequeryingtheseviews,letuscheckwhatisintheresultcache:

/*Monitortheresultcachecomponentsinsharedpool*/

SELECT*

FROMv$sgastat

WHEREPOOL='sharedpool'

andnamelike'Result%'

/

POOLNAMEBYTESCON_ID

----------------------------------------------------------

sharedpoolResultCache:MemoryMgr2080

sharedpoolResultCache:CacheMgr2560

sharedpoolResultCache:StateObjs29280

sharedpoolResultCache1639520

sharedpoolResultCache:BloomFltr20480

Fromtheprecedingqueryoutput,itisevidentthattheresultcacheisacomponentofthesharedpoolandcontainsmemorymanagementdriverssuchasmemorymanager,cachemanager,stateobjects,andbloomfilters.

TheRCBGbackgroundprocesscoordinatestheresultcachemanagementactivities.TheprocessplaysabiggerroleinOracleRACthaninasingleinstancedatabase:

/*QuerytheRCBGbackgroundprocess*/

SELECTpaddr,name,description

FROMv$bgprocess

WHEREname='RCBG'

/

PADDRNAMEDESCRIPTION

-----------------------------------------

00RCBGResultCache:Background

Comingbacktothecachedresults,thefollowingqueryshowsthepropertiesoftheresultsetcachedintheprecedingquery:

/*Querytheresultcacheobjects*/

SELECTstatus,

type,

build_time,

depend_count,

column_count,

scan_count,

row_count

FROMv$result_cache_objects

WHEREcache_id='br0p4fgjgh7jp128u0paxavkns'

/

STATUSTYPEBUILD_TIMEDEPEND_COUNTCOLUMN_COUNTSCAN_COUNT

ROW_COUNT

---------------------------------------------------------------------

---

PublishedResult2113143

Intheprecedingoutput:

BUILD_TIMEisthetimespentinbuildingtheresult(inhundredthsofasecond).DEPEND_COUNTisthecountofdependentobjectsforthisresult.Inthiscase,itisjustthetable(MY_OBJECTS).COLUMN_COUNTisthecountofcolumnsintheresult.SCAN_COUNTisthenumberoftimestheresultisusedbyanSQLquery.ROW_COUNTisthenumberofrowscontainedintheresult.STATUSisthecurrentstatusoftheresult;PUBLISHED,inthiscase.OthervaluesoftheSTATUScolumn,whichyoumightseeindifferentcases,canbe:

NEW:Anunder-constructioncacheresultPUBLISHED:AvalidresultreadyforuseINVALID:Aninvalidatedandnon-usableresultEXPIRED:AresultwhichhascrossedtheexpirationtimeBYPASS:AbypassresultispreventedfrombeingusedbyaSQLquery

TYPEisRESULT.TheothertypecanbeDEPENDENCYfortheobjectswhilebuildinguptheresult.

TipTheNAMESPACEcolumninV$RESULT_CACHE_OBJECTSdetermineswhetheraresultisfromaSQLquerycacheoraPL/SQLfunctioncache.ThefollowingSQLqueryliststhecountofresultsinSQLandPL/SQLresultcachesinthesharedpool:

SELECTnamespace,count(*)


WHEREnamespaceISNOTNULL

GROUPBYnamespace

/

Thefollowingqueryliststheresultcachestatistics.Notethatthevaluesagainstthestatisticnamematchtheresultcachesettings:

/*Querytheresultcacheblockstatistics*/

SELECTid,name,value

FROMV$RESULT_CACHE_STATISTICS

/

IDNAMEVALUE

---------------------------------------------

1BlockSize(Bytes)1024

2BlockCountMaximum25600

3BlockCountCurrent32

4ResultSizeMaximum(Blocks)1280

5CreateCountSuccess1

6CreateCountFailure0

7FindCount0

8InvalidationCount0

9DeleteCountInvalid0

10DeleteCountValid0

11HashChainLength1

12FindCopyCount0

13Latch(Share)0

13rowsselected.

Interpretation:Thesizeofoneresultcacheblockintheservercacheis1kilobyte.Therefore,amaximumof25,600blockscanbeallowedinthecacheandasingleresultsizecancontainamaximumof1,280blocks(5percentof25600).Thecurrentresultcachehasoneresultandintotal32blocksarecurrentlyallocated.

Youcanalsoquerythese32blocksfromV$RESULT_CACHE_MEMORY.Outofthese32blocks,only3areoccupiedwhiletheother29arefree.Themathfor3occupiedblocksisquitesimple.SQLtakes2blockswhilethedependenttable(MY_OBJECTS)consumes1block:

/*Querythecountofoccupiedblocksinresultcachememory*/

SELECTfree,COUNT(*)

FROMv$result_cache_memory

GROUPBYfree

/

FREECOUNT(*)

---------------

NO3

YES29

YoucanquerythedependencymatrixoftheresultsetbyqueryingtheV$RESULT_CACHE_DEPENDENCYdictionaryview:

/*Querythedependenciesofcachedresults*/

SELECTrc.result_id,

o.object_name

FROMV$RESULT_CACHE_DEPENDENCYrc,user_objectso

WHERErc.object_no=o.object_id

/

RESULT_IDOBJECT_NAME

------------------------------

1MY_OBJECTS

InvalidationoftheSQLResultCacheForacachedresulttostayvalid,thestateofdependenttablesanddatamustbepreserved.Ifthetableisalteredortheunderlyingdataisupdated,thecachedresultgetsinvalidated.It’sonlyafterthenextexecutionthatthequeryresultisrebuiltandcachedasanewresult.ThefollowingUPDATEstatementmodifiesonerowintheMY_OBJECTStable.

UPDATEmy_objects

SETobject_name=initcap(object_name)

WHEREobject_id=30

/

COMMIT

/

Theresultinthequeryresultcachegetsinvalidated:

/*Querythecacheresultstatus*/

SELECTcache_id,status



/

CACHE_IDSTATUS

-------------------------------------

br0p4fgjgh7jp128u0paxavknsInvalid

Wewillre-executethegroupbyqueryingtheMY_OBJECTStabletorebuildtheresultinthequeryresultcache:

/*Re-executetheSQLquerytorebuildtheresult*/


object_type,

status,

count(*)

FROMmy_objects



/

/*Querythecacheresultstatus*/

SELECTcache_id,status



/

CACHE_IDSTATUS

------------------------------------

br0p4fgjgh7jp128u0paxavknsPublished

br0p4fgjgh7jp128u0paxavknsInvalid

Notethattheinvalidatedresultisretainedinthequeryresultcacheunlessitismanuallyflushedout,agesout,orthedatabaseinstanceisrestarted.

ReadconsistencyoftheSQLResultCacheTheresultcacheusestheSystemChangeNumber(SCN)tomaintainthereadconsistencyofSQLquerieswhoseresultisretrievedfromtheSQLqueryresultcache.EachandeveryresultaddedtothequeryresultcachealsostorestheSCNuntilitisvalid.Aresultwillstayvalidorconsistentuntilanongoingtransactioniscommitted.

Forexample,intheprecedingcodelisting,notethechangeinSCNwhiletheresultinthequeryresultcachewasinvalidatedandgotrebuiltaftertheSQLwasre-executed:

/*QuerytheSCNnumbersforeachqueryresultcached*/

SELECTcache_id,status,scn



/

CACHE_IDSTATUSSCN

----------------------------------------------

br0p4fgjgh7jp128u0paxavknsPublished7713754

br0p4fgjgh7jp128u0paxavknsInvalid7680436

LimitationsTheSQLresultcachedoesn’tworkwith:

TemporarytablesSYS-orSYSTEM-ownedobjectsSequencepseudocolumns(CURRVALandNEXTVAL)DateandTimeSQLfunctionsTheSYS_CONTEXTfunctionwithanon-constantvariable

PL/SQLFunctionResultCacheYoumustcreateaPL/SQLfunctionwithaRESULT_CACHEclausetoadditsresulttothePL/SQLfunctionresultcache.Whenacache-enabledPL/SQLfunctionisinvokedforthefirsttime,thedatabaselooksintothePL/SQLresultcacheforitsresultwiththematchingarguments.Iftheresultisfound,itisreturnedtothecallingenvironmentwithoutexecutingthefunctionbody.Iftheresultisnotfound,thefunctionbodyisexecutedandtheresultisstoredinthePL/SQLfunctioncache.Uponsubsequentfunctioncallsforthesameinputparameters,theresultisfetcheddirectlyfromthecache.

Notethataresultcachefunctiondoesn’tneedthedependentdatabasetablestoberesult-cached.

NoteOracleDatabase11gRelease1usedtheRELIES_ONclausetospecifythedependentdatasourceswhosestatewouldaffectthestatusofthecachedresult.TheclausewasdeprecatedinOracleDatabase11gRelease2.

Doesitsoundsimilartodeterministicfunctions?DeveloperswhoarefamiliarwithdeterministicfunctionsinPL/SQLmightbethinkingthatthefunctioncachingconceptisquiteclosetodeterministicbehavior.Well,theideaissimilarbutfunctionresultcachingcomeswithmanymorecapabilities.Afunctionisdeterministicifitalwaysreturnsthesameoutputforthesameinputargumentsinagivensessiononly,wheninvokedfromanSQLquery.ThePL/SQLfunctionresultcacheovercomesthelimitationsofadeterministicfunctionbybeingsharableacrosssessionsofthesameuserandcanbeinvokedfromSQLaswellasPL/SQL.

DifferencesbetweenResultCacheandothercachingtechniquesYes,that’sagoodpoint.PriortotheintroductionofthisfeatureinOracleDatabase11g,cachingwasimplementedusingpackagelevelcollectionvariables.ThetwomajordrawbacksofthatapproachwerethatitservedasasessionlevelcacheandconsumedasubstantialamountofProcessGlobalArea(PGA).Beingasession-specificcache,thepackagedvariableswerenotsharablewithothersessions.PGAusagecangrowenormouslyforlargecollectionvariables,whichmayimpactperformance.TheServerresultcachewinsbyawidemarginonthesepoints.Itissharableacrossauser’ssessions,preservesdataintegrity,andmostimportantly,itusestheOracle-managedSGAinsteadofthrottlingthePGA.

IllustrationWewillcreateaPL/SQLfunctionF_COUNT_OBJwiththeRESULT_CACHEclause.Thefunctionreturnsthecountofobjectsforaspecificobjecttype:

/*AfunctionwiththeRESULT_CACHEclause*/

CREATEORREPLACEFUNCTIONf_count_obj(obj_typeVARCHAR2)

RETURNNUMBERRESULT_CACHEIS

l_countNUMBER;

BEGIN

/*Selectquerytofetchrecordcountinalocalvariable*/

SELECTCOUNT(object_type)

INTOl_count

FROMmy_objects

WHEREobject_type=obj_type;

RETURNl_count;

END;

/

WewillinvokethisfunctioninaSELECTstatementandcheckthestatistics:

SETAUTOTRACEON

/*InvokefunctioninSELECTstatementforavalidinput*/

SELECTf_count_obj('PROCEDURE')

FROMDUAL

/

M_PROC_COUNT

------------

214

Statistics

----------------------------------------------------------

2recursivecalls

0dbblockgets

348consistentgets

0physicalreads

0redosize

559bytessentviaSQL*Nettoclient

551bytesreceivedviaSQL*Netfromclient

2SQL*Netroundtripsto/fromclient

0sorts(memory)

0sorts(disk)

1rowsprocessed

Notetheconsistentgetsintheprecedingstatistics.ThisisfortheexecutionoftheSELECTstatementinthefunctionbody.Nowlet’srunthefunctionforthesecondtime:

/*InvokefunctioninSELECTstatementagainforthesameinput*/

SELECTf_count_obj('PROCEDURE')

FROMDUAL

/

M_PROC_COUNT

------------

214

Statistics

----------------------------------------------------------

0recursivecalls

0dbblockgets

0consistentgets

0physicalreads

0redosize




0sorts(memory)

0sorts(disk)

1rowsprocessed

TherewereabsolutelynoconsistentgetsthistimeastheresultisfetcheddirectlyfromthePL/SQLcache.Nowlet’sruntheF_COUNT_OBJfunctionforadifferentinputvalueandcheckthestatistics:

/*InvokefunctioninSELECTstatementforanotherinput*/

SELECTf_count_obj('FUNCTION')

FROMDUAL

/

F_COUNT_OBJ('FUNCTION')

-----------------------

356

Elapsed:00:00:00.09

Statistics

----------------------------------------------------------

4recursivecalls

0dbblockgets

348consistentgets

0physicalreads

0redosize




0sorts(memory)

0sorts(disk)

1rowsprocessed

Onceagain,consistentgetsappearinthestatisticsbecauseadifferentinputissuppliedsothefunctionbodyisexecutedandanewresultsetisaddedtothecache.

MonitoringthePL/SQLResultCacheFormonitoring,wecanquerythedynamicdictionaryviewsandconfirmthecachingofresultsfromthePL/SQLfunction.Thefollowingqueryliststheresultspresentintheservercache:

SELECTcache_id,name,status,depend_count,scan_count

FROMv$result_cache_objects,dba_users

WHEREcreator_uid=user_id

ANDusername='SCOTT'

/

Fromtheprecedingoutput,itisevidentthattherearetworesultsetsinthecache(thatistosay,fortwodifferentinputs).Alsotherearetwodependentobjects—theF_COUNT_OBJfunctionandtheMY_OBJECTStable.Anychangeinthestateofthesetwoobjectswillresultintheinvalidationofthecachedresults.

AnotherpointofinterestisthecacheID.Yes,boththeresultshavethesamecacheID.InthecaseofthePL/SQLfunctioncache,alltheresultshavethesamecacheIDbutdifferentcachekeys.

ThefollowingqueryretrievestwoPL/SQLresultcachestatisticsthatdeterminehowmanyresultswerecreatedinthecache(CreateCountSuccess)andhowmanytimestheywereserved(FindCount):

SELECT*

FROMv$result_cache_statistics

WHERENAMEIN('CreateCountSuccess','FindCount')

/

IDNAMEVALUECON_ID

------------------------------------------


7FindCount20

InvalidationofthePL/SQLResultCacheThefunctionresultcachegetsinvalidatedwhen:

TheunderlyingdatasourcesarealteredorthedataismodifiedThefunctionisrecompiled

Inthenextinvocationofthefunction,theresultisrebuiltandcachedinthePL/SQLfunctionresultcache.Notethattheinvalidatedresultsetwillstillexistandgetsflushedoffbyamanualflushoperationorduringaninstancerestart.Byvirtueofitbeingacache,theresultscanalsogetflushedoffbytheleastrecentlyused(LRU)algorithm.

LimitationThePL/SQLfunctionresultcachedoesnotworkfor:

PipelinedfunctionsOUTandINOUTparametersTheINparameterofBLOB,CLOB,NCLOB,refcursor,collection,object,orrecordBLOB,CLOB,NCLOBreturns,refcursor,collection,object,orrecordAfunctiondeclaredlocallyinananonymousPL/SQLblock

OCIClientresultscacheApplicationswiththeOracleCallInterface(OCI)clientcanlargelybenefitfromtheresultcachefeature.TheresultsfromanSQLqueryandaPL/SQLfunctioncanbecachedwithintheOCIclientprocesscacheandnotinthedatabaseservermemory.Cachingresultsintheclientprocesscachehelpsinmultipleways.First,thequeryresponsetimeimprovesdrasticallyastheresultsareserveddirectlyfromthecachewithoutevenhittingthedatabaseserver.Second,thereducednetworkroundtripsenhanceapplicationperformanceandtheeffectiveutilizationofdatabaseresources.

Howistheconsistencyofresultsintheclientprocesscachemaintained?TheOracleDatabaseserverisresponsibleformonitoringtheconsistencyofcachedresults.Iftheunderlyingdataismodified,thedatabaseservernotifiestheclientprocessandinvalidatestheresultset.Onitsnextroundtriptotheserver,theclientprocessrebuildsthestaleresults.

TheclientresultcacheisindependentofthedatabaseservercacheanddeducesthataresultfromanSQLquerycanbecachedonthedatabaseservercache,theclientprocesscache,orboth.

Tosetuptheclientresultcache,youarerequiredtosetthefollowingparameters:

CLIENT_RESULT_CACHE:Thisdeterminesthemaximumsizeoftheclientprocesscache,whichmustbemorethan32KB.CLIENT_RESULT_CACHE_LAG:Thisspecifiesthetime(inseconds)afterwhichtheOCIcalltothedatabaseisforcedtovalidatethecachedresults.Thedefaultvalueis3,000seconds.COMPATIBLE:ThisistheOracleDatabase-compatibleversion.

TheDBMS_RESULT_CACHEpackageTheOracle-suppliedpackageDBMS_RESULT_CACHEisusedtoregulatetheServerResultCachecomponentofthesharedpool.ThepackageisownedbySYSandonlyprivilegedusersshouldbegrantedtheEXECUTEprivilege.

Thepublicconstantsusedinthepackageareasfollows:

DBMS_RESULT_CACHEconstants(reference:Oracledocumentation)

STATUS_BYPS CONSTANTVARCHAR(10):='BYPASS';

STATUS_DISA CONSTANTVARCHAR(10):='DISABLED';

STATUS_ENAB CONSTANTVARCHAR(10):='ENABLED';

STATUS_SYNC CONSTANTVARCHAR(10):='SYNC';

STATUS_CORR CONSTANTVARCHAR(10):='CORRUPT';

Thesubprogramsusedinthepackagearedescribedinthefollowingtable:

DBMS_RESULT_CACHEsubprograms(reference:Oracledocumentation)

BYPASSprocedure

IfsettoTRUE,theresultcacheusageisbypassedinthecurrentoreverysession.UsedwhenmodifyingandrecompilingaPL/SQLfunctionwhoseresultshavebeencachedearlier.InRAC,sinceeachinstancehasitsownservercache,theBYPASSproceduremustberuninallinstances.

FLUSHfunctionandprocedureFlushesoutalltheresultsfromtheservercache.Youcanalsoretainorreleasememoryandstatistics.Defaultactionisrelease.

INVALIDATEfunctionsandprocedures

Invalidatesalltheresultsthataredependentonagivenobject.Returnsthenumberofresultsinvalidated.

INVALIDATE_OBJECTfunctionsandprocedures Invalidatesthespecifiedresultsetintheservercache.

MEMORY_REPORTprocedure Generatesthesummaryreportfortheserverresultcache.Specify(detailed=>TRUE)togenerateadetailedversionofthereport.

STATUSfunction Checksthestatusoftheresultcache.

DisplayingtheresultcachememoryreportYoucangenerateaservercachememoryreportviatheDBMS_RESULT_CACHEpackage.Asamplecachememoryreport(summarizingresultsfromourillustrations)looksasfollows:

CONNECTsys/oracleassysdba

SETSERVEROUTPUTON

/*Generatethecachememoryreport*/

EXECDBMS_RESULT_CACHE.MEMORY_REPORT

ResultCacheMemoryReport

[Parameters]

BlockSize=1Kbytes

MaximumCacheSize=25Mbytes(25Kblocks)

MaximumResultSize=1280Kbytes(1280blocks)

[Memory]

TotalMemory=169392bytes[0.044%oftheSharedPool]

...FixedMemory=5440bytes[0.001%oftheSharedPool]

...DynamicMemory=163952bytes[0.042%oftheSharedPool]

.......Overhead=131184bytes…....CacheMemory=32Kbytes(32blocks)

...........UnusedMemory=26blocks…........UsedMemory=6

blocks…............Dependencies=2blocks(2count)

...............Results=4blocks…................SQL=2blocks(1

count)

...................PLSQL=2blocks(2count)


Theprecedingreportliststhemaximumcachesize,maximumresultsize,andstandardblocksize.Thereportcanbeinterpretedasfollows:

Theresultcacheisallocatedfromthedynamicsectionofthesharedpool.Currently,only169,392bytesareallocatedandthemaximumstretchisupto25MB.FixedmemoryisthememoryconsumedbyMemoryMgr,CacheMgr,StateObjsandBloomFltr.Outof32Kblocks,only6blocksareused.The6usedblocksinclude2fordependencies(1eachbyF_COUNT_OBJandMY_OBJECTS)and4bysub-pools(2bytheSQLqueryresultcacheand2bythePL/SQLfunctionresultcache—2functioncalls).

YoucanalsogenerateadetailedreportbyspecifyingtheDETAILEDparameterasTRUEintheMEMORY_REPORTprocedure:

execdbms_result_cache.memory_report(TRUE);

ResultCacheMemoryReport

[Parameters]

BlockSize=1Kbytes

MaximumCacheSize=25Mbytes(25Kblocks)

MaximumResultSize=1280Kbytes(1280blocks)

[Memory]

TotalMemory=169392bytes[0.044%oftheSharedPool]

...FixedMemory=5440bytes[0.001%oftheSharedPool]

.......MemoryMgr=208bytes…....CacheMgr=256bytes…....BloomFltr

=2Kbytes…....StateObjs=2928bytes…DynamicMemory=163952bytes

[0.042%oftheSharedPool]

.......Overhead=131184bytes…........HashTable=64Kbytes(4K

buckets)

...........ChunkPtrs=24Kbytes(3Kslots)

...........ChunkMaps=12Kbytes…........Miscellaneous=131184

bytes…....CacheMemory=32Kbytes(32blocks)

...........UnusedMemory=26blocks…........UsedMemory=6

blocks…............Dependencies=2blocks(2count)

...............Results=4blocks…................SQL=2blocks(1

count)

...................PLSQL=2blocks(2count)


OracleDatabase12cenhancementstothePL/SQLfunctionResultCacheUntilOracleDatabase11g,resultsfromaPL/SQLfunctioncreatedwithinvoker’srights(thatis,theAUTHIDCURRENT_USERclause)cannotberesult-cached.Therestrictionwasimposedfromasecuritystandpointasthedatabaseuserscanhavedifferentaccesslevelswhichmaycontradicttheresultcachingmechanism.Forinstance,auserFINexecutesaPL/SQLfunctiontoretrievesalarydetailsofadepartmentandaddstheresulttothecache.AnotheruserCLERKinvokesthesamefunctionandgetstheresultsfromthePL/SQLfunctionresultcache.Haditbeenaninvoker’srightsfunction,hewouldhavereceivedanexception.

StartingfromOracleDatabase12c,theinvoker’srightsfunctioncanberesultcached.Theideaisquitesimple.Whileperformingacachelookup,Oraclepassesthecurrentuseralongwiththefunctionsignature.Whileaddingaresulttothecache,theuserinformationisalsocached.Nexttime,wheneverthefunctionisinvoked,thedatabaseverifieswhetherthecurrentuserhasinvokedthisfunctionearlier.Sonowaresultistightlycoupledwiththeuserwhohasaddeditinthecache.Consequently,aresultissharableacrossthesessionsofthesameuser.

Forexample,thefollowingPL/SQLfunctionisaninvoker’srightsfunctionwiththeresultcachefeature:

/*Createaninvokerrightresultcachefunction*/

CREATEORREPLACEFUNCTIONf_count_myobj(obj_typeVARCHAR2)

RETURNNUMBER

AUTHIDCURRENT_USER

RESULT_CACHEIS

l_countNUMBER;

BEGIN

/*Capturetherecordcountinalocalvariable*/

SELECTCOUNT(object_type)

INTOl_count

FROMmy_objects

WHEREobject_type=obj_type;

RETURNl_count;

END;

/

Functioncreated.

ResultcacheinRealApplicationClustersTheOracleDatabaseRealApplicationCluster(RAC)optionallowsthesharingofaclusterdatabaseacrossmultipledatabaseinstances.Itenhancesthescalabilityandavailabilityofdatabaseapplications.

TheResultcache,beingthenativecomponentofdatabaseinstancememory,issupportedonRACenvironments.ThebehaviorandhandlingofresultcachingonRACisthesameasthatofasingleinstancedatabase.HerearethesalientfeaturesofresultcachinginRAC:

EachRACinstancemaintainsalocalversionoftheServerResultCacheinthesharedpooloftheSGAAresultisaddedtotheinstanceresultcachewhenauserexecutesaSQLqueryoraPL/SQLfunctiononadatabaseinstanceIfthesameuserexecutesthesamequeryfromanotherinstance,thecachedresultiscopiedtothatinstance’sresultcacheoverRACinterconnectThedynamicviewGV$RESULT_CACHE_OBJECTSwillshowduplicateentrieswiththesamecacheID,butfordifferentinstances(INST_ID)Ifthetabledataismodifiedorthetableisaltered,theresultisinvalidatedintheServerResultCacheonalltheinstancesoftheclusterWhicheverinstancere-executesthequery,theresultisrebuiltandcachedforthatinstanceonly

SummaryInthischapter,wehaveexploredthecachingmechanismintheOracleDatabaseserver.WesawhowserverresultcachingcandramaticallyimproveperformanceinSQLandPL/SQLapplications.WelearnedhowtoconfiguretheServerResultCache,howtoenablemanualandautomaticSQLqueryresultcaches,andhowtoworkwiththePL/SQLfunctionresultcache.

Inthenextchapter,wewilllearnaboutPL/SQLcodeprofilingandtracingtechniques.

PracticeexerciseTheinitializationparametersettingsforyourdatabaseareasfollows:

MEMORY_TARGET=500M

RESULT_CACHE_MODE=MANUAL

RESULT_CACHE_MAX_SIZE=0

YouexecuteaquerybyusingtheRESULT_CACHEhint.Whichstatementistrueinthisscenario?

1. Thequeryresultsarenotstoredinthecachebecausenomemoryisallocatedfortheresultcache.

2. ThequeryresultsarestoredinthecachebecauseOracleimplicitlymanagesthecachememory.

3. ThequeryresultsarenotstoredinthecachebecauseRESULT_CACHE_MODEisMANUAL.

4. ThequeryresultsarestoredinthecacheautomaticallywhenRESULT_CACHE_MODEisMANUAL.

Yousetthefollowinginitializationparametersettingsforyourdatabase:

MEMORY_TARGET=500M

RESULT_CACHE_MODE=FORCE

RESULT_CACHE_MAX_SIZE=200M

Youexecutethefollowingquery:

SELECT/*+RESULT_CACHE*/ENAME,DEPTNO

FROMEMPLOYEES

WHEREEMPNO=7844

/

Whichofthefollowingstatementsaretrue?

1. ThequeryresultsarecachedbecauseSQLusestheRESULT_CACHEhint.2. ThequeryresultsarecachedbecausetheresultcachemodeisFORCE.3. ThequeryresultsarenotcachedbecauseSQLusestheRESULT_CACHEhint.4. TheRESULT_CACHEhintisignoredwhentheresultcachemodeisFORCE.

Thecachedqueryresultbecomesinvalidwhenthedataaccessedbythequerygetsmodified.

1. True.2. False.

TheSQLqueryresultcacheispersistentonlyforthecurrentsession.

1. True.2. False.

WhichofthefollowingPL/SQLobjectresultscannotbecached?

1. AStandalonefunction.2. AProcedure.3. Afunctionlocaltoaprocedure.4. APackagedfunction.

TheRELIES_ONclauseinthePL/SQLfunctionresultcachecanbeusedtospecifythedependenttablesorviewswhosestatewouldaffectthecachedresult.

1. True.2. False.

Serversettingsareasfollows:

MEMORY_TARGET=500M

RESULT_CACHE_MODE=FORCE

RESULT_CACHE_MAX_SIZE=200M

IdentifytheSQLquerieswhoseresultscannotbecachedbytheserver.

1. SELECTename,salFROMemployeesWHEREempno=7900;2. SELECTseq_empid.nextvalFROMDUAL;3. SELECTename,sysdate,hiredateFROMemployees;4. SELECTdname,locFROMdepartmentsWHEREdeptno=10;

IdentifythecorrectstatementsaboutthePL/SQLfunctionresultcache.

1. ThePL/SQLfunctionresultcacherequiresadditionalserverconfiguration.2. ThePL/SQLfunctionresultcachecannotbeoperatedonprocedures.3. ThePL/SQLfunctionresultcacheworkswithallcategoriesoffunctions.4. ThePL/SQLfunctionresultcachefeaturescanworkwithfunctionsthattake

collectiontypearguments.

IdentifytheadmissiblevalueoftheSTATUScolumninV$RESULT_CACHE_OBJECTS.

1. PUBLISHED.2. INVALID.3. USED.4. UNUSED.

Choosethecorrectstatementaboutthefollowingsamplecachememorystatisticsreport:

IDNAMEVALUE

---------------------------------------------

1BlockSize(Bytes)1024

2BlockCountMaximum204800

3BlockCountCurrent32

4ResultSizeMaximum(Blocks)40960


6CreateCountFailure0

7FindCount0

8InvalidationCount0

9DeleteCountInvalid0

10DeleteCountValid0

11HashChainLength1

1. CreateCountSuccessisthecountofsuccessfullycachedresults.2. FindCountisthecountofthesuccessfullycachedresultsfoundandusedinthe

queries.3. InvalidationCountisthecountoftheinvalidatedcachedresults.4. BlockCountMaximumisthestaticvalueoftotalblocksavailableinthecache

memory.

Chapter10.Analyzing,Profiling,andTracingPL/SQLCodeDuringthedatabasedevelopmentstageandevenafter,thedevelopersarerequiredtoanalyzeandmaintainthedatabaseobjects.AnalyzingthePL/SQLcodeisanessentialexercisethatenablesyoutodrawoutkeyinformationaboutaprogram.PL/SQLcodeanalysiscanbehelpthedevelopersin:trackingobjectdependencies,unusedvariables,retrievingcompilationsettings,trackingprogramexecutionflow,andbuildingtheperformanceprofileofanobject.

Oracleprovidesapowerfulsetofmetadatasources,knownasdictionaryviews,torevealthemetadataofPL/SQLobjects.Foralltheobjectsthatarecreated,modified,orcompiledinadatabase,Oraclecapturesthemetadataandcontinuestoupdateitateachaction.ThischapterwillfocusonhowtoanalyzeaPL/SQLcodeunit,howtotracetheprogramexecution,andhowtoprofileitinaverysimplisticway.Inthischapter,wewilllearntechniquesto:

AnalyzePL/SQLmetadatainformationthroughdictionaryviewsTracePL/SQLprogramexecutionflowProfilePL/SQLcodeforperformance

AsamplePL/SQLprogramBeforeweplungeintocodeanalysistechniques,letuswritedownastandardPL/SQLprogramfordemonstratingcodeanalysis,profiling,andtracing.ThefollowingPL/SQLprocedurecalculatesthescoreofauserinanexam(Notethatnegativescoringisapplicable).TheprocedureP_CALC_USER_POINTSdeclaresalocalfunctionandaproceduretocalculatethepoints:

/*CreateaPL/SQLprocedure*/

CREATEORREPLACEPROCEDUREp_calc_user_points

(p_userVARCHAR2DEFAULTUSER,p_correctNUMBER,p_wrongNUMBER)

IS

l_numNUMBER;

/*AlocalfunctionF_CALC_POINTS*/

FUNCTIONf_calc_points(p_quesNUMBER,p_factorNUMBER)

RETURNNUMBER

IS

BEGIN

RETURN(p_ques*p_factor);

END;

/*Alocalprocedure*/

PROCEDUREP_NET_CALC(p_net_pointsOUTNUMBER)IS

BEGIN

p_net_points:=f_calc_points(p_correct,4)+f_calc_points(p_wrong,-2);

END;

/*Mainprocedurebody*/

BEGIN

p_net_calc(l_num);

DBMS_OUTPUT.PUT_LINE(USER||'earned'||TO_CHAR(l_num)||'points');

END;

/

WewillnowquerytheOracle-supplieddictionaryviewstofindwaystotrackPL/SQLprogrampropertiessuchasargumentdetails,identifierusage,andobjectcompilationsettings.

TrackingPL/SQLcodinginformationTheOracle-supplieddictionaryviewsareagreatsourceofinformationforperformingdrill-downanalysisofPL/SQLcode.AlthoughthereareseveraldictionariesthatstorePL/SQLobjectinformation,theimportantonesareUSER_ARGUMENTS,USER_OBJECTS,USER_SOURCE,USER_PROCEDURES,andUSER_DEPENDENCIES.TheseviewsalsohavetheirALL_*andDBA_*counterparts.Foryourreference,theUSER,ALL,andDBAcategoryviewsaredescribedasfollows:

USER:ContainsonlytheobjectsthatareownedbyauserALL:ContainstheobjectsthatcanbeaccessedbyauserDBA:ContainsalltheobjectsaccessiblebytheSYSuserorauserwithDBAprivileges

YoucanquerythedatadictionaryviewsfromtheDICTIONARYviewandtheircolumnstructurefromDICT_COLUMNSview.LetusquerythemetadatainformationoftheprocedureP_CALC_USER_POINTSinthesedictionaryviews.

USER_ARGUMENTSTheUSER_ARGUMENTSviewcapturestheargumentinformationofaPL/SQLprogram.Theargumentinformationincludesthepositionofanargumentintheparameterlist,itsdatatype,defaults,andpassmode.

NoteUsageofaNOCOPYhintinanOUTorINOUTparameterisnottrackedinUSER_ARGUMENTS

Thefollowingquerylistsargument_name,itsposition,passmode,data_type,anddefault.

/*QuerytheargumentsoftheprocedureP_CALC_USER_POINTS*/

SELECTargument_name,data_type,defaulted,position,data_level,in_out,

pls_type

FROMuser_arguments

WHEREobject_nameIN('P_CALC_USER_POINTS')

ORDERBYposition

/

ARGUMENT_NAMEDATA_TYPEDPOSITIONDATA_LEVELIN_OUTPLS_TYPE

--------------------------------------------------------

P_USERVARCHAR2Y10INVARCHAR2

P_CORRECTNUMBERN20INNUMBER

P_WRONGNUMBERN30INNUMBER

Intheprecedingqueryresult,theDATA_LEVELrepresentsthelevelofnestinginacompositedatatype.Sincetheprocedurehadscalardatatypesonly,DATA_LEVELiszero.

USER_OBJECTSTheUSER_OBJECTSdictionaryviewistheprimarysourcetocheckthevalidityofaPL/SQLobject.Theviewalsoincludesrelevantdetailssuchascreationandlastupdatetimestamps,namespace,andedition.

/*QuerytheobjectpropertiesofP_CALC_USER_POINTS*/

SELECTobject_id,object_type,status,namespace

FROMuser_objects

WHEREobject_name='P_CALC_USER_POINTS'

/

OBJECT_IDOBJECT_TYPESTATUSNAMESPACE

--------------------------------------------

81410PROCEDUREVALID1

TheORACLE_MAINTAINEDcolumnofthedictionaryviewdeterminesifagivenobjectismanagedbytheOracleDatabaseortheuser.AlltheOracle-suppliedpackages(suchasSTANDARD,DBMS_OUTPUTandallothers)aremaintainedimplicitlybyOracleandcanbequeriedfromALL_OBJECTS.

USER_OBJECT_SIZETheUSER_OBJECT_SIZEviewprovidesthesize(inbytes)ofthesourcecode,parsedcodeandcompiledcodeofaPL/SQLobject.Thesizeinformationcanbequiterelevant,iftheprograminvocationresultsinout-of-memoryissues.DatabasedeveloperscandetermineifalargeprogramcanbebrokendownintosmallersubprogramsormultiplemodulescanbeclubbedunderasinglePL/SQLunit.

ThefollowingqueryshowsthesizeoftheP_CALC_USER_POINTSprocedure:

/*QuerythecodesizeofprocedureP_CALC_USER_POINTS*/

SELECTtype,source_size,parsed_size,code_size,error_size

FROMuser_object_size

WHEREname='P_CALC_USER_POINTS'

/

TYPESOURCE_SIZEPARSED_SIZECODE_SIZEERROR_SIZE

---------------------------------------------------

PROCEDURE47210968270

Intheprecedingoutput,ERROR_SIZEisthesizeoftheerrormessagesraisedduringcodecompilation.

USER_SOURCETheUSER_SOURCEdictionaryviewprovidesthetextsourcecodeofaPL/SQLobject.Thisviewcanbehandyinbuildingupatext-basedcodesearchengine.

ThefollowingqueryshowstheprogrambodyoftheprocedureP_CALC_USER_POINTS:

/*QuerythesourcecodeofP_CALC_USER_POINTS*/

SELECTline,text

FROMuser_source


ORDERBYline

/

LINETEXT

------------------------------------------------------------

1PROCEDUREp_calc_user_points

2(p_userVARCHAR2DEFAULTUSER,p_correctNUMBER,p_wrongNUMBER)

3IS

4l_numNUMBER;

5FUNCTIONf_calc_points(p_quesNUMBER,p_factorNUMBER)

6RETURNNUMBER

7IS

8BEGIN

9RETURN(p_ques*p_factor);

10END;

11

12PROCEDUREP_NET_CALC(p_net_pointsOUTNUMBER)IS

13BEGIN

14p_net_points:=f_calc_points(p_correct,4)+f_calc_points

(p_wrong,-2);

15END;

16

17BEGIN

18p_net_calc(l_num);

19DBMS_OUTPUT.PUT_LINE(USER||'earned'||TO_CHAR(l_num)||'points');

20END;

20rowsselected.

ThefollowingSELECTqueryfindstheobjectsthathavecustomizedexceptionhandlingthroughRAISE_APPLICATION_ERROR:

/*Querytobuildtextbasedcodesearch*/

SELECTDISTINCTowner,name

FROMall_source

WHEREUPPER(text)LIKE'%RAISE_APPLICATION_ERROR%'

/

OWNERNAME

---------------------------------------------

SYSUTL_SMTP

SYSDBMS_STANDARD

SYSUTL_HTTP

APEX_040200WWV_FLOW_ERROR_API

APEX_040200WWV_FLOW_ESCAPE

5rowsselected.

USER_PROCEDURESTheUSER_PROCEDURESdictionaryviewcapturesthesubprogrampropertiesofanobject.Contrarytoitsname(whichjustsays“procedures”),itdisplaysthebehavioralaspectssuchasaggregate,pipelined,parallel,deterministic,orprivilegeauthenticationofnotjustprocedures,butalsoofPL/SQLfunctionsandPL/SQLpackages.

TheproceduralpropertiesoftheP_CALC_USER_POINTSsubprogramcanbequeriedfromtheviewasfollows:

/*QuerythesubprogrampropertiesofP_CALC_USER_POINTS*/

SELECTobject_type,

aggregate,

pipelined,

parallel,

interface,

deterministic,

authid

FROMuser_procedures


/

OBJECT_TYPEAGGPIPPARINTDETAUTHID

----------------------------------------

PROCEDURENONONONONODEFINER

USER_PLSQL_OBJECT_SETTINGSandUSER_STORED_SETTINGSTheUSER_PLSQL_OBJECT_SETTINGSandUSER_STORED_SETTINGSviewsareusedtodisplaythecompilationparametervaluesofaPL/SQLobject.ThedifferencebetweenthetwoviewsisthattheUSER_PLSQL_OBJECT_SETTINGSviewcontainsacolumnforeachcompilationparameter,whiletheUSER_STORED_SETTINGSviewstoresparametervaluesasakey-valuepair(theparameternameasthekey)foraPL/SQLprogram.

Let’scheckthevalueofcompilationparametersfrombothoftheviews.ThefollowingSELECTpivotqueryshowsthecompilationparametervaluesfortheprocedureP_CALC_USER_POINTS:

/*QuerythecompilationparametersforP_CALC_USER_POINTS*/

SELECTname,pname,pval

FROMuser_plsql_object_settings

UNPIVOTINCLUDENULLS

(

pvalFOR(pname)IN

(

PLSQL_CODE_TYPEas'PLSQL_CODE_TYPE',

PLSQL_DEBUGas'PLSQL_DEBUG',

PLSQL_WARNINGSas'PLSQL_WARNINGS',

NLS_LENGTH_SEMANTICSas'NLS_LENGTH_SEMANTICS',

PLSQL_CCFLAGSas'PLSQL_CCFLAGS',

PLSCOPE_SETTINGSas'PLSCOPE_SETTINGS'

)

)


/

NAMEPNAMEPVAL

--------------------------------------------------------

P_CALC_USER_POINTSPLSQL_CODE_TYPNATIVE

P_CALC_USER_POINTSPLSQL_DEBUGFALSE

P_CALC_USER_POINTSPLSQL_WARNINGSDISABLE:ALL

P_CALC_USER_POINTSNLS_LENGTH_SEMANTICSBYTE

P_CALC_USER_POINTSPLSQL_CCFLAGS

P_CALC_USER_POINTSPLSCOPE_SETTINGSIDENTIFIERS:ALL

6rowsselected.

/*QuerythecompilationparametersforP_CALC_USER_POINTS*/

SELECTobject_name,param_name,param_value

FROMuser_stored_settings


/

OBJECT_NAMEPARAM_NAMEPARAM_VALUE

---------------------------------------------------------------

P_CALC_USER_POINTSplsql_optimize_level2

P_CALC_USER_POINTSplsql_code_typeNATIVE

P_CALC_USER_POINTSplsql_debugFALSE

P_CALC_USER_POINTSnls_length_semanticsBYTE

P_CALC_USER_POINTSplsql_warningsDISABLE:ALL

P_CALC_USER_POINTSplsql_ccflags

P_CALC_USER_POINTSplscope_settingsIDENTIFIERS:ALL

P_CALC_USER_POINTSplsql_compiler_flagsNATIVE,NON_DEBUG

8rowsselected.

USER_DEPENDENCIESTheUSER_DEPENDENCIESdictionaryviewgivesyouthelistofobjectsonwhichagivenPL/SQLsubprogramisdependent.Ifanyofthesedependentobjectsgetsinvalidated,thePL/SQLprogramwillalsobeinvalidated.ThefollowingqueryliststheobjectsthatarereferencedintheP_CALC_USER_POINTSfunction:

/*QuerythedependentobjectsofP_CALC_USER_POINTS*/

SELECTreferenced_owner,

referenced_namername,

referenced_typertype,

dependency_typedtype

FROMuser_dependencies


/

OWNERRNAMERTYPEDTYP

----------------------------------------------------

SYSSTANDARDPACKAGEHARD

SYSSYS_STUB_FOR_PURITY_ANALYSISPACKAGEHARD

PUBLICDBMS_OUTPUTSYNONYMHARD

TheDBMS_DESCRIBEpackageTheDBMS_DESCRIBEpackageisanOraclesuppliedpackagethatisusedtodescribethestructureofaPL/SQLobject.Intermsoffunctionality,theDBMS_DESCRIBEpackagegivesinformationthatissimilartoUSER_ARGUMENTSorUSER_PROCEDURES,butitisusedwheretheprogramstructurehastobeexposedbasedonaclientrequest.ItisownedbySYSanditspublicsynonymisavailabletoallusers.

TheDBMS_DESCRIBEpackagecontainsonesubprogramDESCRIBE_PROCEDUREandusesassociativearraystocapturethePL/SQLobjectstructure.

TYPEVARCHAR2_TABLEISTABLEOFVARCHAR2(30)

INDEXBYBINARY_INTEGER;

TYPENUMBER_TABLEISTABLEOFNUMBER

INDEXBYBINARY_INTEGER;

ThefollowingPL/SQLblockretrievesthesignatureofthePL/SQLprocedureP_CALC_USER_POINTS:

SETSERVEROUTPUTON

DECLARE

/*Declarethelocalvariablesofassociativearraytype*/

v_overloadDBMS_DESCRIBE.NUMBER_TABLE;

v_positionDBMS_DESCRIBE.NUMBER_TABLE;

v_levelDBMS_DESCRIBE.NUMBER_TABLE;

v_arg_nameDBMS_DESCRIBE.VARCHAR2_TABLE;

v_datatypeDBMS_DESCRIBE.NUMBER_TABLE;

v_def_valueDBMS_DESCRIBE.NUMBER_TABLE;

v_in_outDBMS_DESCRIBE.NUMBER_TABLE;

v_lengthDBMS_DESCRIBE.NUMBER_TABLE;

v_precisionDBMS_DESCRIBE.NUMBER_TABLE;

v_scaleDBMS_DESCRIBE.NUMBER_TABLE;

v_radixDBMS_DESCRIBE.NUMBER_TABLE;

v_spareDBMS_DESCRIBE.NUMBER_TABLE;

BEGIN

/*CalltheprocedureDESCRIBE_PROCEDUREforP_CALC_USER_POINTS*/

DBMS_DESCRIBE.DESCRIBE_PROCEDURE

(object_name=>'P_CALC_USER_POINTS',

reserved1=>null,

reserved2=>null,

overload=>v_overload,

position=>v_position,

level=>v_level,

argument_name=>v_arg_name,datatype=>v_datatype,

default_value=>v_def_value,

in_out=>v_in_out,

length=>v_length,

precision=>v_precision,

scale=>v_scale,

radix=>v_radix,

spare=>v_spare,

include_string_constraints=>null);

FORiINv_arg_name.FIRST..v_arg_name.LAST

LOOP

DBMS_OUTPUT.PUT_LINE(RPAD('_',40,'_'));

/*Checkifthepositionifzeroornot*/

IFv_position(i)=0THEN

/*ZeropositionisreservedforRETURNtypes*/

DBMS_OUTPUT.PUT_LINE('RETURNtypeofthefunction:');

DBMS_OUTPUT.PUT_LINE(rpad('FunctionReturntype:',30,'

')||v_datatype(i));

ELSE

/*Printtheargumentname*/

DBMS_OUTPUT.PUT_LINE(RPAD('Parametername:',30,'')||v_arg_name(i));

ENDIF;

/*Displaytheposition,typeandmodeofparameters*/

DBMS_OUTPUT.PUT_LINE(rpad('Parameterposition:',30,'')||

v_position(i));

DBMS_OUTPUT.PUT_LINE(rpad('Parameterdatatype:',30,'')||

casev_datatype(i)

when1then'VARCHAR2'

when2then'NUMBER'

when3then'BINARY_INTEGER'

when8then'LONG'

when11then'ROWID'

when12then'DATE'

when23then'RAW'

when24then'LONGRAW'

when58then'OPAQUETYPE'

when96then'CHAR'

when106then'LONGRAW'

when121then'OBJECT'

when122then'NESTEDTABLE'

when123then'VARRAY'

when178then'TIME'

when179then'TIMEWITHTIMEZONE'

when180then'TIMESTAMP'

when230then'PL/SQLRECORD'

when251then'PL/SQLTABLE'

when252then'PL/SQLBOLLEAN'

end);

DBMS_OUTPUT.PUT_LINE(rpad('Parameterdefault:',30,'')||

casev_def_value(i)

when0then'NoDefault'

when1then'Defaulted'

end);

DBMS_OUTPUT.PUT_LINE(rpad('Parameterpassmode:',30,'')||

casev_in_out(i)

when0then'INmode'

when1then'OUTmode'

when2then'INOUTmode'

end);

DBMS_OUTPUT.PUT_LINE(rpad('_',40,'_'));

ENDLOOP;

END;

/

________________________________________

Parametername:P_USER

Parameterposition:1

Parameterdatatype:VARCHAR2

Parameterdefault:Defaulted

Parameterpassmode:INmode

________________________________________

________________________________________

Parametername:P_CORRECT

Parameterposition:2

Parameterdatatype:NUMBER

Parameterdefault:NoDefault


________________________________________

________________________________________

Parametername:P_WRONG

Parameterposition:3

Parameterdatatype:NUMBER

Parameterdefault:NoDefault


________________________________________


TrackingtheprogramexecutionsubprogramcallstackThecallstackinformationletsyoudeterminethestagesofprogramexecution.Aprogramcallstackincludesthenestedinformationofthereferencedsubprograms.YoucantrackthecallstackforaprogramusingtheDBMS_UTILITY.FORMAT_CALL_STACKfunctionorUTL_CALL_STACKpackage.

ThefunctionFORMAT_CALL_STACKreturnsthecurrentcallstackinformation,whichincludestheobjecthandlenumber,linenumber,andthenameofthesubprogram.

Let’screatethreestandaloneprocedures:P1,P2,andP3.P3invokesP2,whileP2invokesP1.BythetimetheprogramcontrolreachesP1,thecallstackincludesP1,P3andP2.

/*CreatetheprocedureP1*/

CREATEORREPLACEPROCEDUREP1

IS

BEGIN

DBMS_OUTPUT.PUT_LINE('ExecutingP1..');

DBMS_OUTPUT.PUT_LINE(RPAD('~',15,'~'));

DBMS_OUTPUT.PUT_LINE(dbms_utility.format_call_Stack);

END;

/



IS

BEGIN


DBMS_OUTPUT.PUT_LINE('CallingP1..');


/*CallprocedureP1*/

P1;

END;

/



IS

BEGIN


DBMS_OUTPUT.PUT_LINE('CallingP2..');


/*CallprocedureP2*/

P2;

END;

/

/*Enabletheserveroutputtodisplaytheerrormessages*/

SETSERVEROUTPUTON

/*StartaPL/SQLblocktoinvokeP3*/

BEGIN

/*CallP3*/

P3;

END;

/

ExecutingP3..

CallingP2..

~~~~~~~~~~~~~~~

ExecutingP2..

CallingP1..

~~~~~~~~~~~~~~~

ExecutingP1..

~~~~~~~~~~~~~~~

-------PL/SQLCallStack-------

objecthandlelinenumberobjectname

0xec4c4ce06procedureSCOTT.P1

0xec4382208procedureSCOTT.P2

0xe4e004488procedureSCOTT.P3

0xe4c982981anonymousblock


Intheprecedingprogramoutput,youcanchecktheprogramexecutionflowfromP3toP2,followedbyP1.ButoneissuewiththeFORMAT_CALL_STACKoutputistheinabilitytoextractthedrill-downuptolocalroutineinformationanduseitfordebuggingtasks.

OracleDatabase12cintroducesanewAPI,knownasUTL_CALL_STACK,togiveastructuredcallstackaswellaserrorstack.Thestructuredcallstackoutputallowsdeveloperstoextracttheinformationanduseitfordebugpurposes.

TheprocedureSHOW_CALL_STACKusestheUTL_CALL_STACKsubprogramstodisplaythestructuredcallstackinformation:

/*CreatetheproceduretoprintcallstackusingUTL_CALL_STACK*/

CREATEORREPLACEPROCEDUREshow_call_stack

is

lvlPLS_INTEGER;

BEGIN

/*Retrievethedynamicdepthofthecallstack*/

lvl:=UTL_CALL_STACK.DYNAMIC_DEPTH();

/*Iteratethecalldepthstructure*/

FORiIN1..lvlLOOP

DBMS_OUTPUT.put_line(

RPAD('Calldepth:'||UTL_CALL_STACK.lexical_depth(i),15)||

RPAD('Line:'||TO_CHAR(UTL_CALL_STACK.unit_line(i),'99'),15)||

UTL_CALL_STACK.CONCATENATE_SUBPROGRAM

(UTL_CALL_STACK.SUBPROGRAM(i))

);

ENDLOOP;

END;

/

Intheprecedingprocedure:

DYNAMIC_DEPTHdenotesthenumberofsubprogramsinthecallstackLEXICAL_DEPTHistherelativecalldepthwithinasubprogramUNIT_LINEisthelinenumberwherethecallstatementismadeSUBPROGRAMreturnsthenameofthesubprogramcurrentlyunderexecutionCONCATENATE_SUBPROGRAMconcatenatesasubprogramnametoitscallingprogram

P_CALC_POINT_CALLSTACKinvokesSHOW_CALL_STACKtoprintthestructuredcallstack:

/*CreateaproceduretoinvokeSHOW_CALL_STACK*/

CREATEORREPLACEPROCEDUREp_calc_point_callstack

(p_userVARCHAR2,p_correctNUMBER,p_wrongNUMBER)

IS

l_numNUMBER;


RETURNNUMBER

IS

BEGIN

/*InvokeSHOW_CALL_STACK*/

show_call_stack;


END;

PROCEDUREp_net_calc(p_net_pointsOUTNUMBER)IS

BEGIN


END;

BEGIN

p_net_calc(l_num);

DBMS_OUTPUT.PUT_LINE(USER||'earned'||TO_CHAR(l_num)||'points');

end;

/

ExecutetheprecedingprocedureinaPL/SQLblock:

SETSERVEROUTPUTON

BEGIN

p_calc_point_callstack(user,10,3);

END;

/

Calldepth:1Line:10P_CALC_POINT_CALLSTACK.F_CALC_POINTS

Calldepth:1Line:15P_CALC_POINT_CALLSTACK.P_NET_CALC

Calldepth:0Line:18P_CALC_POINT_CALLSTACK

Calldepth:0Line:2__anonymous_block

Calldepth:0Line:6SHOW_CALL_STACK

Calldepth:1Line:10P_CALC_POINT_CALLSTACK.F_CALC_POINTS

Calldepth:1Line:15P_CALC_POINT_CALLSTACK.P_NET_CALC

Calldepth:0Line:18P_CALC_POINT_CALLSTACK

Calldepth:0Line:2__anonymous_block

SCOTTearned34points


Theprecedingoutputshowsthecallstackinlast-in-first-outorder.Toreadthestackfrom

toptobottom,youcanloopthedynamicdepthinREVERSEorder.

TrackingpropagatingexceptionsinPL/SQLcodeTraditionally,databasedevelopersarekeentouseSQLERRMandSQLCODEtofindanexceptioncodeandmessage.Inamodularprogrammingapproach,PL/SQLprogramsinvokeroutinesanditmayhappenthataroutinecallfailswithanexception.Theexceptionpropagatestothecallingblockandtraversesthroughmultipleblocksinsearchofitshandler.

Ifyouwanttotrackthepathofpropagatingexceptions,youcaneitherusetheFORMAT_ERROR_BACKTRACEfunctionfromDBMS_UTILITYorthenewUTL_CALL_STACKpackage.

ThePL/SQLprocedurehereraisesuser-definedexceptionstodemonstratetheworkingofback-tracingtheexceptions:

/*Createaproceduretotraceprinterrorstack*/

CREATEORREPLACEPROCEDUREp_calc_point_errStack


IS

l_numNUMBER;

/*Declareuserdefinedexceptions*/

myFunExpEXCEPTION;

myProcExpEXCEPTION;

myBlkExpEXCEPTION;

PRAGMAEXCEPTION_INIT(myFunExp,-20020);

PRAGMAEXCEPTION_INIT(myProcExp,-20021);

PRAGMAEXCEPTION_INIT(myBlkExp,-20022);

/*Explicitlyraisetheuserdefinedexceptioninthelocalfunction*/


RETURNNUMBER

IS

BEGIN

RAISEmyFunExp;


EXCEPTION

WHENmyFunExpTHEN

RAISEmyProcExp;

END;

/*Explicitlyraisetheuserdefinedexceptioninthelocalprocedure*/


BEGIN


EXCEPTION

WHENmyProcExpTHEN

RAISEmyBlkExp;

END;

/*Explicitlyraisetheuserdefinedexceptionintheprogrambody*/

BEGIN

p_net_calc(l_num);

DBMS_OUTPUT.PUT_LINE(USER||'earned'||to_char(l_num)||'points');

EXCEPTION

WHENmyBlkExpTHEN

DBMS_OUTPUT.PUT_LINE(DBMS_UTILITY.FORMAT_ERROR_BACKTRACE);

END;

/

Uponexecution,theblockgivesthefollowingoutput:

SETSERVEROUTPUTON

BEGIN

p_calc_point_errstack(USER,10,3);

END;

/

ORA-06512:at"SCOTT.P_CALC_POINTS_ERRSTACK",line28




Notethat,sincetheexceptionintheinnerblockisnothandledintheexceptionsectionsoftheouterblocks,itpropagatesthroughthelinenumbers19(F_CALC_POINTS),27(P_NET_CALC),and31(P_CALC_POINTS_ERRSTACK).

Onceagain,FORMAT_ERROR_BACKTRACEpresentsanoutputwhichishardtoparseanddoesn’tincludethenamesoflocalsubprograms.Let’sre-writetheprogramusingUTL_CALL_STACK.

ThefollowingprocedureDISPLAY_ERROR_STACKshowstheerrorstackalongwiththeerrornumbersraisedintheerrorblock:

/*CreateaproceduretoprinterrorstackusingUTL_CALL_STACK*/

CREATEORREPLACEPROCEDUREdisplay_error_stackAS

l_depthPLS_INTEGER;

BEGIN

/*Retrievethecountoftheerrorstack*/

l_depth:=UTL_CALL_STACK.ERROR_DEPTH;

/*Iteratetheerrorstackstructuretoprinterrors*/

FORiIN1..l_depthLOOP

DBMS_OUTPUT.put_line(

RPAD(i,10)||

RPAD('ORA-'||LPAD(UTL_CALL_STACK.error_number(i),5,'0'),10)||

UTL_CALL_STACK.error_msg(i)

);

ENDLOOP;

END;

/

Intheprecedingprogramcode:

ERROR_DEPTHisthecountoferrorsintheerrorstackERROR_NUMBERandERROR_MSGaretheerrornumberandstatementoftheerrorinthestack

/*RewritetheprocedurallogictoinvokeDISPLAY_ERROR_STACK*/

CREATEORREPLACEPROCEDUREp_calc_point_errStack


IS

l_numNUMBER;

/*Declareuser-definedexceptions*/

myFunExpEXCEPTION;

myProcExpEXCEPTION;

myBlkExpEXCEPTION;

PRAGMAEXCEPTION_INIT(myFunExp,-20020);

PRAGMAEXCEPTION_INIT(myProcExp,-20021);

PRAGMAEXCEPTION_INIT(myBlkExp,-20022);

/*Explicitlyraisetheuserdefinedexceptioninthelocalfunction*/


RETURNNUMBER

IS

BEGIN

RAISEmyFunExp;


EXCEPTION

WHENmyFunExpTHEN

RAISEmyProcExp;

END;

/*Explicitlyraisetheuserdefinedexceptioninthelocalprocedure*/


BEGIN

p_net_points:=f_calc_points(p_correct,4)+f_calc_points

(p_wrong,-2);

EXCEPTION

WHENmyProcExpTHEN

RAISEmyBlkExp;

END;

/*Explicitlyraisetheuserdefinedexceptionintheprogrambody*/

BEGIN

p_net_calc(l_num);

DBMS_OUTPUT.PUT_LINE(USER||'earned'||to_char(l_num)||'points');

EXCEPTION

WHENmyBlkExpTHEN

display_error_stack;

END;

/

ExecutetheprocedureP_CALC_POINT_ERRSTACK:

SETSERVEROUTPUTON

BEGIN

p_calc_point_errStack(user,10,3);

END;

/

1ORA-20022

2ORA-06512at"SCOTT.P_CALC_POINT_ERRSTACK",line27

3ORA-20021

4ORA-06512at"SCOTT.P_CALC_POINT_ERRSTACK",line19

5ORA-20020


DeterminingidentifiertypesandusagesAlexicalunitinaPL/SQLprogramcodeisbuiltupusingliterals,identifiers,delimiters,andcomments.AllitemsthataredeclaredinaPL/SQLprogramasvariables,cursors,constants,andsubprogramnamesareidentifiers.Identifierscanbereservedwords(suchasBEGINandEND),predefined(declaredgloballywithinSTANDARDpackage),orquoted.

USER_IDENTIFIERSTheUSER_IDENTIFIERSdictionaryviewreportstheusageofidentifiersinaPL/SQLprogramunit.Theviewincludesinformationaboutanidentifier’sname,itstype,andusagebylinenumberinaPL/SQLprogram.

Trackingidentifierdetailsforallthesubprogramswouldbeadditionaltaskduringcodecompilationandtherefore,itiscollectedonlyforenabledPL/SQLobjects.

ThestructureoftheUSER_IDENTIFIERSviewisasfollows:

NameNull?Type

-----------------------------------------------

NAMEVARCHAR2(128)

SIGNATUREVARCHAR2(32)

TYPEVARCHAR2(18)

OBJECT_NAMENOTNULLVARCHAR2(128)

OBJECT_TYPEVARCHAR2(13)

USAGEVARCHAR2(11)

USAGE_IDNUMBER

LINENUMBER

COLNUMBER

USAGE_CONTEXT_IDNUMBER

ORIGIN_CON_IDNUMBER

Keypointstonote:

TheSIGNATUREistheuniquecodeofanidentifieranddifferentiatesidentifierswiththesamenameUseofanidentifiercanbeDECLARATION,DEFINITION,ASSIGNMENT,CALL,orREFERENCE

UseofanidentifierinaprogramunitisuniquelyidentifiedbyitsUsageIDorthecombinationofline,column,andusageTheUSAGE_CONTEXT_IDestablishesaself-referencingintegritywiththeusageID

ThePL/ScopetoolThePL/ScopetoolwasintroducedinOracleDatabase11gtocapturetheuseofidentifiersinaPL/SQLprogram.TheidentifierdetailsarestoredintheSYSAUXtablespaceandcanbequeriedfromtheUSER_IDENTIFIERSdictionaryview(oritsALL_*orDBA_*views).

NoteYoucanusethePL/ScopetoolfromSQLDeveloper.

KeyfeaturesofthePL/Scopetoolareasfollows:

Thefeaturecanbeenabledatthedatabaseinstanceorsessionlevel.APL/SQLsubprogramcanbecompiledforPL/Scope.ThePL/Scopetoolcannotcaptureinformationforobfuscatedsubprograms.ThePL/ScopetoolcannotcollecttheidentifierinformationiftheSYSAUXtablespaceisabsent.However,noerrorisraisedbutawarningisstoredintheUSER_ERRORSview.

ThePLSCOPE_SETTINGSparameterThecompilationparameterPLSCOPE_SETTINGSenablesthecollectionofidentifierdatainaPL/SQLprogram.Bydefault,theparameterisdisabled(IDENTIFIERS:NONE).ItshouldbesettoIDENTIFIERS:ALLinordertoenableidentifiertracking.

Ifyouenablethisparameterattheinstancelevel,Oraclewillcapturedatabasewideidentifierinformation.Youmustbecarefulwhilesettingthisparameteratthedatabaseinstancelevelasitmightimpactthecompilationperformanceoflargepackages.

SettingPLSCOPE_SETTINGSatsystemorsessionlevel:

ALTER[SYSTEM|SESSION]

SETPLSCOPE_SETTINGS=['IDENTIFIERS:ALL'|'IDENTIFIERS:NONE']

Beingacompilationparameter,youcanalsocompileaPL/SQLsubprogramforidentifiertrackingbyspecifyingthePLSCOPE_SETTINGSparameter:

ALTER[PROGRAMNAME]COMPILE

PLSCOPE_SETTINGS=['IDENTIFIERS:ALL'|'IDENTIFIERS:NONE']

YoucanquerythecurrentsettingofthePLSCOPE_SETTINGSparameterfromtheV$PARAMETERdynamicdictionaryview.

/*ViewthecurrentsettingofPLSCOPE_SETTINGSparameter*/

SELECTvalue

FROMv$parameter

WHEREname='plscope_settings'

/

VALUE

-----------------

IDENTIFIERS:NONE

YoucanviewthespaceconsumedbythePL/ScopetoolinSYSAUXtablespacebyrunning

thefollowingqueryasSYSDBA:

/*VerifythePL/ScopeoccupancyinSYSAUXtablespace*/

SELECToccupant_desc,schema_name,space_usage_kbytes

FROMv$sysaux_occupants

WHEREoccupant_name='PL/SCOPE'

/

OCCUPANT_DESCSCHEMA_NAMESPACE_USAGE_KBYTES

------------------------------------------------------------

PL/SQLIdentifierCollectionSYS2496

LetusrecompiletheprocedureP_CALC_USER_POINTSwiththePLSCOPE_SETTINGSparameter:

ALTERPROCEDUREp_calc_user_pointsCOMPILE

PLSCOPE_SETTINGS='IDENTIFIERS:ALL'

/

QuerytheUSER_PLSQL_OBJECT_SETTINGSviewtoverifywhethertheidentifierinformationhasbeencaptured:

SELECTplscope_settings

FROMuser_plsql_object_settings


/

PLSCOPE_SETTINGS

------------------

IDENTIFIERS:ALL

OracleDatabasedocumentationprovidesahandyscriptforgeneratingahierarchicalreportofprogramidentifiersbyitsusage.ThefollowingscriptgeneratesthePL/ScopeidentifierreportfromtheUSER_IDENTIFIERSdictionaryview:

WITHvAS

(

SELECTline,col,

name,

LOWER(type)Type,

LOWER(usage)Usage,

usage_id,

usage_context_id

FROMuser_identifiers


ANDobject_type='PROCEDURE'

)

SELECTline,RPAD(LPAD('',2*(level-1))||name,25,'.')||''||

RPAD(Type,15)||RPAD(Usage,15)IDENTIFIER_USAGE_CONTEXTS

FROMv

STARTWITHusage_context_id=0

CONNECTBYPRIORusage_id=usage_context_id

ORDERSIBLINGSBYline,col

/

LINEIDENTIFIER_USAGE_CONTEXTS

----------------------------------------------------------------

1P_CALC_USER_POINTS….....proceduredeclaration

1P_CALC_USER_POINTS…...proceduredefinition

1P_USER….............formalindeclaration

1P_USER….............formalinassignment

1USER….............functioncall

1VARCHAR2…...........characterdatatypereference

1P_CORRECT…..........formalindeclaration

1NUMBER….............numberdatatypereference

1P_WRONG…............formalindeclaration


3L_NUM…..............variabledeclaration


4F_CALC_POINTS…......functiondeclaration

4F_CALC_POINTS…......functiondefinition

4P_QUES…...........formalindeclaration

4NUMBER….........numberdatatypereference

4P_FACTOR….........formalindeclaration


5NUMBER…...........numberdatatypereference

9P_QUES…...........formalinreference

9P_FACTOR….........formalinreference

12P_NET_CALC….........proceduredeclaration

12P_NET_CALC….........proceduredefinition

12P_NET_POINTS….....formaloutdeclaration


14P_NET_POINTS….....formaloutassignment

1F_CALC_POINTS…..functioncall

14P_CORRECT…....formalinreference

14F_CALC_POINTS…..functioncall

14P_WRONG…......formalinreference

17P_NET_CALC….........procedurecall

17L_NUM…..............variablereference

32rowsselected.

Inasimilarwaytotheprecedingquery,applicationdeveloperscanexploremultipleusecaseswhereidentifierinformationcanbeuseful.

TheDBMS_METADATApackageTheDBMS_METADATApackagewasintroducedinOracle9i.TheAPIenablestheextractionofobjectmetadatafromdatabasedictionariesthatcanbeoptionallymanipulatedandre-executedonadatabaseserver.ThepackageisownedbySYSwhosepublicsynonymisusedbyallusers.AuserwithSELECT_CATALOG_ROLEcandirectlyaccesstheDBMS_METADATApackage.

NoteDBMS_METADATAisakeyenablerofmetadataexportfunctionalityinDataPump

Thepackagepullstheobject’smetadatainXMLformfromthedatabasedictionaryandprovidestransformhandlerstobuilditinthedesiredform.TheformattedXMLcanthenbere-executedinthedatabase.

DBMS_METADATAdatatypesandsubprogramsAswesaidearlier,theDBMS_METADATApackageusesthepublicsynonymsofSYS-owneddatastructures.ThefollowinglistshowsSYS-ownedobjecttypes:

SYS.KU$_PARSED_ITEM:Anobjecttypeusedtocapturetheattributesofanobject’smetadata.Theobjecttypestructureisasfollows:

CREATETYPEsys.ku$_parsed_itemASOBJECT

(

itemVARCHAR2(30),

valueVARCHAR2(4000),

object_rowNUMBER

)

ITEM,VALUEformtheattributename-valuepairforOBJECT_ROW.

SYS.KU$_PARSED_ITEMS:AnestedtableofSYS.KU$PARSED_ITEMusedtoholdtheobjectmetadataattributesformultipleobjects.SYS.KU$_DDL:AnobjecttypeusedtocapturetheDDLofanobjectalongwithitsparsediteminformation.Theobjecttypestructureisasfollows:

CREATETYPEsys.ku$_ddlASOBJECT

(

ddlTextCLOB,

parsedItemsys.ku$_parsed_items

)

TheparsedobjectinformationisstoredinPARSEDITEM.

SYS.KU$_DDLS:AnestedtableofSYS.KU$_DDLreturnedbytheFETCH_DDLsubprogramusedtoholdthemetadataofanobjecttransformedintomultipleDDLstatements.SYS.KU$_MULTI_DDL:AnobjecttypeusedtoholdtheDDLforanobjectinmultipletransforms.SYS.KU$_MULTI_DDLS:AnestedtableofSYS.KU$_MULTI_DDLreturnedbytheCONVERTsubprogram.SYS.KU$_ERRORLINE:Anobjecttypeusedtocaptureerrorinformation.Theobjecttypestructureisasfollows:

CREATETYPEsys.ku$_ErrorLineISOBJECT

(

errorNumberNUMBER,

errorTextVARCHAR2(2000)

)

SYS.KU$_ERRORLINES:AnestedtableoftheSYS.KU$_ERRORLINEobjecttypeusedtoholdbulkerrorinformationduringextractionofeachDDLstatement.SYS.KU$_SUBMITRESULT:AnobjecttypeusedtocapturethecompleteerrorinformationincurredinaDDLstatement.Theobjecttypestructureisasfollows:

CREATETYPEsys.ku$_SubmitResultASOBJECT

(

ddlsys.ku$_ddl,

errorLinessys.ku$_ErrorLines

)

SYS.KU$_SUBMITRESULTS:AnestedtableoftheSYS.KU$_SUBMITRESULTobjecttypeusedtoholdmultipleDDLstatementsandassociatederrorinformation.

NoteAcompletelistofsubprogramscanbefoundonOracledocumentationathttps://docs.oracle.com/database/121/ARPLS/d_metada.htm

ThefollowingtableshowsthefrequentlyusedsubprogramsoftheDBMS_METADATApackage:

Subprogram Remarks

ADD_TRANSFORMfunction SpecifiesatransformthatFETCH_[XML|DDL|CLOB]appliestotheXMLrepresentationoftheretrievedobjects

CLOSEprocedure InvalidatesthehandlereturnedbyOPENandcleansuptheassociatedstate

CONVERTfunctionsandprocedures ConvertanXMLdocumenttoDDL

FETCH_[XML|DDL|CLOB]functionsandprocedures

ReturnsmetadataforobjectsmeetingthecriteriaestablishedbyOPEN,SET_FILTER,SET_COUNT,ADD_TRANSFORM,andsoon

GET_[XML|DDL|CLOB]functions FetchesthemetadataforaspecifiedobjectasXMLorDDLinasinglecall

GET_QUERYfunction ReturnsthetextofthequeriesthatareusedbyFETCH_[XML|DDL|CLOB]

OPENfunction Specifiesthetypeofobjecttoberetrieved,theversionofitsmetadata,andtheobjectmodel

OPENWfunction Opensawritecontext

PUTfunction SubmitsanXMLdocumenttothedatabase

SET_COUNTprocedure SpecifiesthemaximumnumberofobjectstoberetrievedinasingleFETCH_[XML|DDL|CLOB]call

SET_FILTERprocedure Specifiesrestrictionsontheobjectstoberetrieved—forexample,theobjectnameorschema

SET_PARSE_ITEMprocedure Enablesoutputparsingbyspecifyinganobjectattributetobeparsedandreturned

SET_TRANSFORM_PARAMandSET_REMAP_PARAMprocedures SpecifiesparameterstotheXSLTstylesheetsidentifiedbytransform_handle

Outoftheprecedinglist,thesubprogramscanbegroupedbasedontheirworkfunction:

Subprogramsusedtoretrievemultipleobjectsfromthedatabase

SubprogramsusedtosubmitXMLmetadatatothedatabase

https://docs.oracle.com/database/121/ARPLS/d_metada.htm

ADD_TRANSFORMfunction ADD_TRANSFORMfunction

CLOSEprocedure CLOSEprocedure2

FETCH_[XML|DDL|CLOB]functionsandprocedures CONVERTfunctionsandprocedures

GET_QUERYfunction OPENWfunction

GET_[XML|DDL|CLOB]functions PUTfunction

OPENfunction SET_PARSE_ITEMprocedure

SET_COUNTprocedure SET_TRANSFORM_PARAMandSET_REMAP_PARAMprocedures

SET_FILTERprocedure

SET_PARSE_ITEMprocedure

SET_TRANSFORM_PARAMandSET_REMAP_PARAMprocedures

ParameterrequirementsYoumustnotethattheparameterstothemetadataAPIarecase-sensitiveandshouldbepassedintheirrespectivepositiononly(nonamednotation).

TheDBMS_METADATAtransformationparametersandfiltersAslistedintheprecedingAPIlist,theSET_TRANSFORM_PARAMsubprogramisusedtoformatandcontroltheDDLoutput.Itisusedforbothretrievalandsubmissionofmetadatafromortothedatabase.Itisanoverloadedprocedurewiththefollowingsyntax:

DBMS_METADATA.SET_TRANSFORM_PARAM

(

transform_handleINNUMBER,

nameINVARCHAR2,

valueINVARCHAR2,

object_typeINVARCHAR2DEFAULTNULL

);


(


nameINVARCHAR2,

valueINBOOLEANDEFAULTTRUE,


);


(


nameINVARCHAR2,

valueINNUMBER,


);

Intheprecedingprogramsignature:

TRANSFORM_HANDLE:AhandlereitherfromADD_TRANSFORM,oragenerichandlerconstantSESSION_TRANSFORMusedtoaffectthewholesessionNAME:NameoftheparametertobemodifiedVALUE:Newvalueoftheparameter

Thefollowingisalistofthecommonsetofparametersthatareapplicabletoallobjectsinaschema:

Parameter Value Meaning

PRETTY TRUE|FALSE(defaultvalueisTRUE) IfTRUE,producesproperlyindentedoutput

SQLTERMINATOR TRUE|FALSE(defaultvalueisFALSE) IfTRUE,appendsSQLterminator(;or/)aftereachDDL

DEFAULT TRUE|FALSE IfTRUE,resetsallparameterstotheirdefaultstate

INHERIT TRUE|FALSE IfTRUE,inheritssession-levelsettings

Transformhandlersapplicablefortablesandviewsareasfollows:

Parameter Value Meaning

SEGMENT_ATTRIBUTESTRUE|FALSE(defaultvalueisTRUE)

IfTRUE,includessegment,tablespace,logging,andphysicalattributes

STORAGETRUE|FALSE(defaultvalueisFALSE) IfTRUE,includesstorageclause

TABLESPACE TRUE|FALSE IfTRUE,includestablespacespecification

CONSTRAINTS TRUE|FALSE IfTRUE,includestableconstraints

REF_CONSTRAINTS TRUE|FALSE IfTRUE,includesreferentialconstraints

CONSTRAINTS_AS_ALTER TRUE|FALSE IfTRUE,includesconstraintsintheALTERTABLEstatements

OID TRUE|FALSE IfTRUE,includestheobjecttableOID

SIZE_BYTE_KEYWORD TRUE|FALSE IfTRUE,includestheBYTEkeywordsinstringtypecolumnspecifications

FORCE TRUE|FALSE IfTRUE,createsviewwiththeFORCEoption

TheDBMS_METADATA.SET_FILTERprocedureisusedtospecifythefiltersontheschemaobjects.Itacceptsthemetadatahandle,filtername,anditsvalueasinputarguments.

PROCEDUREset_filter(

handleINNUMBER,

nameINVARCHAR2,

valueINVARCHAR2|BOOLEAN|NUMBER,

object_type_pathVARCHAR2

)

Frequentlyusedfilterscanbeschema,user,objectdependencies,tabledata,tables,indexes,constraints,andsoon.Therearemorethan70filtersavailableinOracle11g.Itcanbesetasfollows:

DBMS_METADATA.SET_FILTER(handle,'SCHEMA','SCOTT');

DBMS_METADATA.SET_FILTER(handle,'NAME','DEPARTMENTS');

DemonstrationLetusretrievetheDDLoftheentireEMPtableintheSCOTTschema.TheSQLqueryreturnsaCLOBoutput:

/*QuerytoretrieveDDLofEMPtable*/

SELECTdbms_metadata.get_ddl('TABLE','EMP','SCOTT')

FROMDUAL

/

CREATETABLE"SCOTT"."EMP"

("EMPNO"NUMBER(4,0),

"ENAME"VARCHAR2(10),

"JOB"VARCHAR2(9),

"MGR"NUMBER(4,0),

"HIREDATE"DATE,

"SAL"NUMBER(7,2),

"COMM"NUMBER(7,2),

"DEPTNO"NUMBER(2,0),

"EMAIL"VARCHAR2(50),

CONSTRAINT"PK_EMP"PRIMARYKEY("EMPNO")

USINGINDEX

PCTFREE10

INITRANS2

MAXTRANS255

COMPUTESTATISTICS

STORAGE(INITIAL65536

NEXT1048576

MINEXTENTS1

MAXEXTENTS2147483645

PCTINCREASE0

FREELISTS1

FREELISTGROUPS1

BUFFER_POOLDEFAULT

FLASH_CACHEDEFAULT

CELL_FLASH_CACHEDEFAULT)

TABLESPACE"USERS"ENABLE,

CONSTRAINT"FK_DEPTNO"

FOREIGNKEY("DEPTNO")

REFERENCES"SCOTT"."DEPT"("DEPTNO")ENABLE)

SEGMENTCREATIONIMMEDIATE

PCTFREE10PCTUSED40INITRANS1MAXTRANS255

NOCOMPRESSLOGGING

STORAGE(INITIAL65536

NEXT1048576

MINEXTENTS1

MAXEXTENTS2147483645

PCTINCREASE0

FREELISTS1

FREELISTGROUPS1

BUFFER_POOLDEFAULT

FLASH_CACHEDEFAULT

CELL_FLASH_CACHEDEFAULT)

TABLESPACE"USERS"

Intheprecedingoutput,ifyouwishtoskipthestorageclausespecificationforthetable,youcandosobysettingthetransformparameters:

/*Anonymousblocktosettransformhandles*/

BEGIN


(DBMS_METADATA.SESSION_TRANSFORM,'STORAGE',false);


(DBMS_METADATA.SESSION_TRANSFORM,'SEGMENT_ATTRIBUTES',false);


(DBMS_METADATA.SESSION_TRANSFORM,'PRETTY',true);


(DBMS_METADATA.SESSION_TRANSFORM,'SQLTERMINATOR',true);


(DBMS_METADATA.SESSION_TRANSFORM,'REF_CONSTRAINTS',false);


(DBMS_METADATA.SESSION_TRANSFORM,'TABLESPACE',false);


(DBMS_METADATA.SESSION_TRANSFORM,'SIZE_BYTE_KEYWORD',false);

END;

/

Now,ifyouexecutetheGET_DDLfunctiontoretrievetheDDLoftheEMPtable,theoutputwillbemuchneaterandcleaner:

/*QuerytoretrieveDDLofEMPtable*/

SELECTdbms_metadata.get_ddl('TABLE','EMP','SCOTT')

FROMDUAL

/

CREATETABLE"SCOTT"."EMP"

("EMPNO"NUMBER(4,0),

"ENAME"VARCHAR2(10),

"JOB"VARCHAR2(9),

"MGR"NUMBER(4,0),

"HIREDATE"DATE,

"SAL"NUMBER(7,2),

"COMM"NUMBER(7,2),

"DEPTNO"NUMBER(2,0),

"EMAIL"VARCHAR2(50),

CONSTRAINT"PK_EMP"PRIMARYKEY("EMPNO")

USINGINDEXENABLE

);

YoucanusetheGET_XMLfunctiontoretrievetheXMLformatoftheEMPtable.

ThefollowingSQLqueryretrievestheobjectgrantsoftheEMPtableusingtheGET_DEPENDENT_DDLfunction:

/*QuerytoretrieveDDLofobjectgrantsofEMP*/

SELECT

DBMS_METADATA.GET_DEPENDENT_DLL('OBJECT_GRANT','EMP','SCOTT')OBJ_GRANTS

FROMDUAL

/

GRANTSELECTON"SCOTT"."EMP"TO"SALES";

GRANTSELECTON"SCOTT"."EMP"TO"MGR";

GRANTSELECTON"SCOTT"."EMP"TO"CLERK";

GRANTINSERTON"SCOTT"."EMP"TO"SALES";

GRANTINSERTON"SCOTT"."EMP"TO"MGR";

GRANTINSERTON"SCOTT"."EMP"TO"CLERK";

YoucanalsoretrievetheDDLfortheindexesonthetablecolumns.ThefollowingSELECTquerydisplaystheDDLfortheuniqueindexontheEMPNOcolumnoftheEMPtable:

/*QuerytoretrieveDDLofprimarykeyinEMPtable*/

SELECTDBMS_METADATA.GET_DDL('INDEX','PK_EMP','SCOTT')

FROMDUAL

/

CREATEUNIQUEINDEX"SCOTT"."PK_EMP"ON"SCOTT"."EMP"("EMPNO")

;

TracingPL/SQLprogramsusingDBMS_TRACETracingprogramexecutionisanimportantexerciseinascrumbaseddatabasedevelopmentenvironment.Sometimes,inamodularprogrammingmodel,itbecomesdifficulttotracktheprogramexecutionpath.OracleprovidestheDBMS_TRACEpackagetotracePL/SQLprogramcode.

DBMS_TRACEisanOraclesuppliedpackagethatcanbeusedtoenableanddisabletracingindatabasesessions.TheprogramexecutionpathistracedwhenyouexecuteaPL/SQLprograminatrace-enabledsession.Thetraceinformationiscapturedandstoredindatabasetables.ThesetracetablescanbefurtheranalyzedtoexaminetheexecutionpathofaPL/SQLprogram.

ThefollowingfigureshowsthestepsinvolvedinPL/SQLcodetracing:

NotePL/SQLcodetracingcannotbedoneinasharedserverenvironment

InstallingtheDBMS_TRACEpackageYoucaninstalltheDBMS_TRACEpackagebyrunningthefollowingscriptsfromthe$ORACLE_HOME/rdbms/adminfolder:

dbmspbt.sql:ThisscriptcreatestheDBMS_TRACEpackagespecificationprvtpbt.plb:ThisscriptcreatestheDBMS_TRACEpackagebody

TipThescriptsmustbeexecutedastheSYSuserandinthesameorder.

DBMS_TRACEsubprogramsTheDBMS_TRACEpackagecontainstraceconstantsandmembersubprograms.Thetraceconstantsareusedtospecifythetracinglevelinasession.

NoteForcompletedetails,pleaserefertotheOracledocumentationathttps://docs.oracle.com/database/121/ARPLS/d_trace.htm.

TheDBMS_TRACEconstantsaresummarizedasfollows:

DBMS_TRACEconstant Default Remarks

TRACE_ALL_CALLS 1 Tracesallcalls

TRACE_ENABLED_CALLS 2 Tracescallsthatareenabledfortracing

TRACE_ALL_EXCEPTIONS 4 Tracesallexceptions

TRACE_ENABLED_EXCEPTIONS 8 Tracesexceptionsthatareenabledfortracing

TRACE_ALL_SQL 32 TracesallSQLstatements

TRACE_ENABLED_SQL 64 TracesSQLstatementsthatareenabledfortracing

TRACE_ALL_LINES 128 Traceseachline

TRACE_ENABLED_LINES 256 Traceslinesthatareenabledfortracing

TRACE_PAUSE 4096 Pausestracing(controlsthetracingprocess)

TRACE_RESUME 8192 Resumetracing(controlsthetracingprocess)

TRACE_STOP 16384 Stopstracing(controlsthetracingprocess)

TRACE_LIMIT 16 Limitsthetraceinformation(controlsthetracingprocess)

TRACE_MINOR_VERSION 0 Administersthetracingprocess

TRACE_MAJOR_VERSION 1 Administersthetracingprocess

NO_TRACE_ADMINISTRATIVE 32768

Preventstracingofadministrativeeventssuchas:

PL/SQLTraceToolstarted

Traceflagschanged

PL/SQLVirtualMachinestarted

PL/SQLVirtualMachinestopped

NO_TRACE_HANDLED_EXCEPTIONS 65536 Preventstracingofhandledexceptions

ThesubprogramscontainedintheDBMS_TRACEpackageareasfollows:

DBMS_TRACEsubprogram Remarks

https://docs.oracle.com/database/121/ARPLS/d_trace.htm

CLEAR_PLSQL_TRACEprocedure Stopstracedatadumpinginsession

GET_PLSQL_TRACE_LEVELfunction Getsthetracelevel

GET_PLSQL_TRACE_RUNNUMBERfunction Getsthecurrentsequenceofexecutionoftrace

PLSQL_TRACE_VERSIONprocedure Getstheversionnumberofthetracepackage

SET_PLSQL_TRACEprocedure Startstracinginthecurrentsession

COMMENT_PLSQL_TRACEprocedure IncludescommentonthePL/SQLtracing

INTERNAL_VERSION_CHECKfunction Hasavalueas0,iftheinternalversioncheckhasnotbeendone

LIMIT_PLSQL_TRACEprocedure SetslimitforthePL/SQLtracing

PAUSE_PLSQL_TRACEprocedure PausesthePL/SQLtracing

RESUME_PLSQL_TRACEprocedure ResumesthePL/SQLtracing

Intheprecedinglist,thekeysubprogramsare:

SET_PLSQL_TRACE:ItkicksoffthePL/SQLtracingsession.Forexample,DBMS_TRACE.SET_PLSQL_TRACE(DBMS_TRACE.TRACE_ALL_SQL)tracesallSQLintheprogram.CLEAR_PLSQL_TRACE:Itstopsthetracingsession.

ThePLSQL_TRACE_VERSIONreturnsthecurrenttraceversionastheOUTparameter.

NoteThetracelevelthatcontrolsthetracingprocess(stop,pause,resume,andlimit)cannotbeusedincombinationwithothertracelevels

CompilingaPL/SQLprogramfordebuggingAPL/SQLsubprogramcanbetracedonlyafteritiscompiledindebugmode.YoumustcompiletheprogramtobetracedbyspecifyingthePLSQL_OPTIMIZE_LEVELas1.(Inearlierreleases,thecompilationparameterPLSQL_DEBUGwasusedtocompileaprogramfordebug.)

NoteThePLSQL_DEBUGparameterhasbeendeprecatedinOracleDatabase12c,butretainedforbackward-compatibility.OraclerecommendstousePLSQL_OPTIMIZE_LEVELas1tocompileaPL/SQLprogramfordebugging.

ViewingthePL/SQLtraceinformationThetraceinformationisloggedintothetracetablesthatcanbecreatedbyinvokingthe$ORACLE_HOME/rdbms/admin/tracetab.sqlscriptfromtheSYSaccount.Thesuccessfulexecutionofthescriptwillcreatethefollowingtwotables:

PLSQL_TRACE_RUNS:Thetablestoresexecution-specificinformation.RUNIDisauniquerunidentifierthatderivesitsvaluefromasequence,PLSQL_TRACE_RUNNUMBER.TheRUN_DATEandRUN_ENDcolumnsspecifythestartandendtimeoftherunrespectively.TheRUN_SYSTEM_INFOandSPARE1columnsarecurrentlyunusedcolumnsinthetable.PLSQL_TRACE_EVENTS:Thistabledisplaysthetracesoftheprogramexecutionpath.Thetablestructureisdescribedasfollows:

TheRUNIDcolumnreferencestheRUNIDcolumnofthePLSQL_TRACE_RUNStableTheEVENT_SEQistheuniqueeventidentifierwithinasinglerunTheEVENT_UNIT,EVENT_UNIT_KIND,EVENT_UNIT_OWNER,andEVENT_LINEcolumnscapturetheprogramunitinformation(suchasname,type,owner,andlinenumber)thatinitiatesthetraceeventThePROC_NAME,PROC_UNIT,PROC_UNIT_KIND,PROC_OWNER,andPROC_LINEcolumnscapturetheprocedureinformation(suchasname,type,owner,andlinenumber)thatiscurrentlytracedTheEXCPandUSER_EXCPcolumnsapplytotheexceptionsoccurringduringthetraceTheEVENT_COMMENTcolumngivesauser-definedcommentortheactualeventdescriptionTheMODULE,ACTION,CLIENT_INFO,CLIENT_ID,ECID_ID,andECID_SEQcolumnscaptureinformationaboutthesessionrunningonaSQL*PlusclientTheCALLSTACKandERRORSTACKcolumnsstorethecallstackinformation

Oncethescripthasbeenexecuted,theDBAcanoptionallycreatetheirpublicsynonymsthatcanbeaccessedbyallusers.

/*ConnectasSYSDBA*/

Connsys/oracleasSYSDBA

/*CreatesynonymforPLSQL_TRACE_RUNS*/

CREATEPUBLICSYNONYMplsql_trace_runsFORplsql_trace_runs

/

/*CreatesynonymforPLSQL_TRACE_EVENTS*/

CREATEPUBLICSYNONYMplsql_trace_eventsFORplsql_trace_events

/

/*CreatesynonymforPLSQL_TRACE_RUNNUMBERsequence*/

CREATEPUBLICSYNONYMplsql_trace_runnumberFORplsql_trace_runnumber

/

/*GrantprivilegesonthePLSQL_TRACE_RUNS*/

GRANTselect,insert,update,deleteONplsql_trace_runsTOPUBLIC

/

/*GrantprivilegesonthePLSQL_TRACE_EVENTS*/

GRANTselect,insert,update,deleteONplsql_trace_eventsTOPUBLIC

/

/*GrantprivilegesonthePLSQL_TRACE_RUNNUMBER*/

GRANTselectONplsql_trace_runnumberTOPUBLIC

/

StepstotracePL/SQLprogramexecutionPL/SQLtracingisdemonstratedinthefollowingsteps:

1. CompiletheprocedureP_CALC_USER_POINTSfordebugbyspecifyingPLSQL_OPTIMIZE_LEVELas1:

ALTERPROCEDUREp_calc_user_pointsCOMPILEPLSQL_OPTIMIZE_LEVEL=1

/

2. Enabletracinginthesession:

Notethetracelevelswhileenablingtracinginthecurrentsession.ThefollowingPL/SQLblockwillenabletracingofallcallsexcludingthetracingofadministrativeevents.

BEGIN

/*Enabletracingforallcallsinthesession*/

DBMS_TRACE.SET_PLSQL_TRACE(

DBMS_TRACE.TRACE_ALL_CALLS+

DBMS_TRACE.NO_TRACE_ADMINISTRATIVE);

END;

/

3. ExecutetheprocedureP_CALC_USER_POINTS:

SETSERVEROUTPUTON

BEGIN

p_calc_user_points(USER,10,3);

END;

/

4. Disabletracinginthesession:

BEGIN

/*Stopthetracesession*/

DBMS_TRACE.CLEAR_PLSQL_TRACE;

END;

/

5. QuerythetracelogtablesPLSQL_TRACE_RUNSandPLSQL_TRACE_EVENTS:

QuerytheRUNIDofthecurrenttracefromPLSQL_TRACE_RUNS

SELECTMAX(runid)

FROMPLSQL_TRACE_RUNS

WHERErun_owner='SCOTT'

/

MAX(RUNID)

----------

13

ForRUNID=13,querythetraceeventsfromPLSQL_TRACE_EVENTS

SELECTevent_seq,

event_comment,

event_unit_owner||'.'||event_unitunit,

proc_name,

proc_unit,

proc_unit_kind

FROMPLSQL_TRACE_EVENTS

WHERERUNID=13

ORDERBYEVENT_SEQ

/

ProfilingPL/SQLcodeOracleenablesdatabasedeveloperstoperformdynamicanalysisoftheirPL/SQLcodethroughtracingandprofiling.Asanapplicationdeveloper,youwriteamulti-linePL/SQLsubprogram,whichmayincludeSQLstatements,PL/SQLconstructs,callstoroutinesubprograms,exceptions,andmanymoreitems.YoucanfollowtheexecutionflowoftheprogrambyusingtheDBMS_TRACEpackage,butitdoesn’trevealthetimeconsumedateachstep.YoucanprofilethePL/SQLprogramtocheckitsperformanceaspects.TheperformanceprofilerevealshowmuchtimeisspentateachlineofcodeinaPL/SQLprogram.

Profilingisavitalexerciseinthedevelopmentstageofadatabase,asyoucanidentifytheareasinyourPL/SQLprogramcodethatcanbefine-tunedforperformance.Oracleprovidestwobuilt-inutilitypackagestoprofilePL/SQLcode:DBMS_PROFILERandDBMS_HPROF.TheDBMS_PROFILERpackagegatherstheperformancemetricsandproducesaflatprofileroutput.Ontheotherhand,DBMS_HPROFgatherstheprofilerdataandwritestheprofileinformationintointeractiveHTMLreports.

Inthescopeofthischapter,wewilldiscusstheDBMS_HPROFpackage.

TheDBMS_HPROFpackageTheDBMS_HPROFpackagewasintroducedinOracleDatabase11gRelease1.ItenableshierarchicalprofilingofaPL/SQLprogramandprovidesadetailedperformanceanalysisoftimespentbysubprogramcalls,bynamespace,andbycalldescendantsthroughtheHTMLreports.Itisknownasa“hierarchicalprofiler”becauseofitsabilitytodrill-downtodescendantandsub-treelevelsofasubprogramexecution.Thedistinctivefeaturesofahierarchicalprofilerareasfollows:

ItgathersandstoresprofilerinformationintodatabasetablesItissupportedbySQLDeveloperItreportstheperformanceofSQLandPL/SQLexecutionintheprogramThenumberofdistinctsubprogramscallsandtimespentineachoneofthemThesubprogramcallhierarchy

TheDBMS_HPROFpackageisinstalledbydefaultandisexecutedwiththeinvoker’sprivileges.AusershouldhavetheEXECUTEprivilegeontheSYS-ownedDBMS_HPROFtool.

DifferencesbetweenDBMS_PROFILERandDBMS_HPROFDBMS_PROFILERprofilesagivenPL/SQLprogramatthelinelevel,whileDBMS_HPROFbuildsacalllevelprofileofaprogram.DBMS_HPROFiseasytouseandrequiresnoadditionaleffortswhenrunoncriticaldatabaseenvironments.DBMS_PROFILERproducesflatoutputwhiletherawdatafromDBMS_HPROFcanbefurtheranalyzedandwrittenintoHTMLreports.

DBMS_HPROFsubprogramsTheDBMS_HPROFpackagecontainsthesubprogramstocollecttheprofiledata(DataCollector)andanalyzeit(Analyzer).

DataCollector:Thefollowingsubprogramsopenandclosetheprofilingwindow.AllthePL/SQLprogramsexecutedwithinthiswindowwillbeprofiledandwritteninrawformattoafile.

START_PROFILINGprocedureSTOP_PROFILINGprocedure

Analyzer:TheANALYZEsubprogramreadsandanalyzestherawprofilerdataandpopulatestheprofilertables.Youcananalyzeeitherthecompleterawprofilerdataorevenaparticularsubprogramcall.OraclealsoletsyouprofiletheallocationofUGA(UserGlobalArea)andPGA(ProgramGlobalArea)forafunctionduringtheprogramexecution.

CollectingrawprofiledataWewilllistthestepstoprofiletheexecutionoftheP_CALC_USER_POINTSprocedure:

1. Createadatabasedirectory.Oraclewillcreatetherawprofilerdataoutputfileinthislocation:

connectsys/oracleasSYSDBA

CREATEDIRECTORYdir_profiles

AS'/u01/app/oracle/diag/profiles/'

/

2. MakethenecessarygrantstotheSCOTTuser.Thisstepisanimportantpre-requisiteforausertousetheDBMS_HPROFpackage:

connectsys/oracleasSYSDBA

GRANTREAD,WRITEONDIRECTORYdir_profilesTOSCOTT

/

GRANTEXECUTEONDBMS_HPROFTOSCOTT

/

3. Enableprofilinginthecurrentsession:

connectscott/tiger

BEGIN

DBMS_HPROF.START_PROFILING('DIR_PROFILES','hprof_p_calc.log');

END;

/

4. ExecutetheP_CALC_USER_POINTSprocedure:

connectscott/tiger

SETSERVEROUTON

BEGIN

P_CALC_USER_POINTS(USER,10,3);

END;

/

5. Stopprofilinginthesession

connectscott/tiger

BEGIN

/*Stoptheprofiling*/

DBMS_HPROF.STOP_PROFILING;

END;

/

6. Checktherawprofilerdatacreatedatthespecifieddirectorylocation:

Oraclegatherstheprofilerdataintextformatbuttherawformatishardtointerpretanddrawconclusionsfrom.Followingarethefirstinitiallinesoftherawprofilerdata:

P#VPLSHPROFInternalVersion1.0

P#!PL/SQLTimerStarted

P#CPLSQL."".""."__plsql_vm"

P#X14

P#CPLSQL."".""."__anonymous_block"

P#X334

P#CSQL."SYS"."STANDARD"::11."__static_sql_exec_line180"#180

P#X3504

P#R

P#X132056

P#C

PLSQL."SCOTT"."P_CALC_USER_POINTS"::7."P_CALC_USER_POINTS"#9d831f6c5a52

6d3e#1

P#X224

P#C

PLSQL."SCOTT"."P_CALC_USER_POINTS"::7."P_CALC_USER_POINTS.P_NET_CALC"#e

17d780a3c3eae3d#12

P#X1

InterpretingtherawprofilerdataAlthoughtherawprofilerdataisabittrickytounderstandandinterpret,youcangetfirst-levelindicationsfromthefollowinginformation.

Eventindicators—eachlineoftheprofilerstartswithaneventindicator,whichcarriesameaning.Herearethedistincteventindicatorsfromtheprofileroutput:

P#V:PLSHPROFbannerinformationP#!:CommentP#C:CalltoSQLorPL/SQLsubprogram:

Determinesthecallnamespace,linenumber,callingandcalledsubprogramname,andhashsignature.

P#X:ElapsedtimebetweenthetwoeventsP#R:Returnfromasubprogramcall

Operationalfunctions—FunctionstoexecuteaPL/SQLprogramcanbethefollowing:

__anonymous_blockindicatesanonymousblockexecution__dyn_sql_exec_lineindicatesdynamicSQLexecutionatline#__pkg_initindicatesPL/SQLpackageinitialization__plsql_vmindicatesPL/SQLvirtualmachinecall__sql_fetch_lineindicatesfetchoperationatline#__static_sql_exec_lineindicatesstaticSQLexecutionatline#

AnalyzingprofilerdataAftertherawprofilerdataiscollected,wewillanalyzeitandpopulatetheprofilertables.Letusnowcreatetheprofilertables.

CreatingtheprofilertablesBydefault,theprofilertablesarenotcreated.Therefore,eithertheSYSDBAortheuserwithDBAprivilegeswillhavetorunthe$ORACLE_HOME/rdbms/admin/dbmshtab.sqlscripttocreatetheprofilertables.Onexecutionofthisscript,thefollowingthreetablesarecreated:

DBMSHP_RUNS:MaintainsflatinformationabouteachcommandexecutedduringprofilingDBMSHP_FUNCTION_INFO:ContainsinformationabouttheprofiledfunctionDBMSHP_PARENT_CHILD_INFO:Containsparent-childprofilerinformation

AdatabaseadministratorcancreateapublicsynonymontheprecedingtablesorgranttheSELECTprivilegetotheuserwhointendstousetheprofiler.

AnalyzingtheprofileroutputBeforeinvokingthesubprogramtoanalyzetherawprofilerdata,firstgrantobjectprivilegestotheSCOTTuser:


GRANTselect,insertonDBMSHP_RUNStoscott

/

GRANTselect,insertonDBMSHP_FUNCTION_INFOtoscott

/

GRANTselect,insertonDBMSHP_PARENT_CHILD_INFOtoscott

/

ThefollowingPL/SQLanonymousblockinvokestheANALYZEsubprogramtointerpretthetracefilepassedastheparameter:

connectscott/tiger


DECLARE

l_runidNUMBER;

BEGIN

/*InvoketheanalyzerAPI*/

l_runid:=DBMS_HPROF.analyze

(location=>'DIR_PROFILES',

FILENAME=>'hprof_p_calc.log',

run_comment=>'AnalyzingtheexecutionofP_CALC_USER_POINTS');

DBMS_OUTPUT.put_line('l_runid='||l_runid);

END;

/

Queryingtheprofilertables

YoucanqueryprofilerdatafromtheDBMSHP_RUNS,DBMSHP_FUNCTION_INFO,andDBMSHP_PARENT_CHILD_INFOtables.ThefollowingSQLqueryselectsthemostrecentRUNIDfromtheDBMSHP_RUNStable:

SELECTrunid,total_elapsed_time,run_comment

FROMdbmshp_runs

ORDERBYrunid

/

RUNIDTOTAL_ELRUN_COMMENT

---------------------------------------------------------------

219973AnalyzingtheexecutionofP_CALC_USER_POINTS

ThefollowingSQLqueryselectsthesubprograminformationfromDBMSHP_FUNCTION_INFO:

SELECTnamespace,

function,

module,

calls,

function_elapsed_time"time_ms"

FROMdbmshp_function_info

WHERErunid=2

/

NAMESFUNCTIONMODULECALLS

time_ms

-----------------------------------------------------------------------

------

PLSQL__anonymous_block2

132558

PLSQL__plsql_vm223

PLSQLP_CALC_USER_POINTSP_CALC_USER_POINTS12489

PLSQLP_CALC_USER_POINTS.F_CALC_POINTSP_CALC_USER_POINTS214

PLSQLP_CALC_USER_POINTS.P_NET_CALCP_CALC_USER_POINTS16

PLSQLSTOP_PROFILINGDBMS_HPROF10

PLSQLPUT_LINEDBMS_OUTPUT13

SQL__static_sql_exec_line180STANDARD23727

8rowsselected.

Theprecedingoutputshowsthetimeelapsedineachprogramfunctionalongwiththenamespacetowhichitbelongs.Theprofilerdatainthetablescanbeusedtobuildcustomreportsindevelopmenttools.

TheplshprofutilityOracleprovidesacommand-lineutilitytool,calledplshprof,toperformin-depthanalysisofrawprofilerdataandgenerateneatHTMLreports.Itcanalsobeusedtogenerateadifferencereportbetweentworawprofileroutputfiles.Thetoolisnotdependentontheanalyzerphaseortheprofilertable’sdata.

Theplshprofutilitysyntaxisasfollows:

[oracle@packt~]$plshprof

PLSHPROF:OracleDatabase12cEnterpriseEditionRelease12.1.0.2.0-64bit

Production

Usage:plshprof[<option>...]<tracefile1>[<tracefile2>]

Options:

-trace<symbol>(nodefault)specifyfunctionnameoftreeroot

-skip<count>(default=0)skipfirst<count>invokations

-collect<count>(default=1)collectinfofor<count>invokations

-output<filename>(default=<symbol>.htmlor<tracefile1>.html)

-summaryprinttimeonly

Inthefollowingexample,theplshprofutilitysummarizestherawprofilerdatafromtheloghprof_p_calc.log.

[oracle@profiles]$plshprof-summaryhprof_p_calc.log


Production

Totalsubtreetime:138820microsecs(elapsedtime)

Notethatthesummaryonlygivesyouthetotalelapsedtime.LetusnowfullyanalyzetheprofilerdataandgeneratetheHTMLoutput:

[oracle@profiles]$plshprof-outputHPROF_PCALChprof_p_calc.log


Production

[8symbolsprocessed]

[Reportwrittento'HPROF_PCALC.html']

Oncetheplshprofutilityisprocessed,thefollowingHTMLfilesaregeneratedinthedirectorylocation:

[oracle@profiles]$ls*.html

HPROF_PCALC_2c.htmlHPROF_PCALC_mf.htmlHPROF_PCALC_tc.html

HPROF_PCALC_2f.htmlHPROF_PCALC_ms.htmlHPROF_PCALC_td.html

HPROF_PCALC_2n.htmlHPROF_PCALC_nsc.htmlHPROF_PCALC_tf.html

HPROF_PCALC_fn.htmlHPROF_PCALC_nsf.htmlHPROF_PCALC_ts.html

HPROF_PCALC.htmlHPROF_PCALC_nsp.html

HPROF_PCALC_md.htmlHPROF_PCALC_pc.html

Here,HPROF_PCALC.htmlisthereportindexfileandlinksallotherprofilerreports.Themainindexpageisshowninthefollowingscreenshot:

Whatdothesereportsreveal?Thevariousreportsgiveadetailedbreakdownofelapsedtimebyeachprogramfunction,module,descendent,andnamespace.Let’sexplorethemainreportsfromthecompleteset:

FunctionElapsedTime(microsecs)DatasortedbyTotalSubtreeElapsedTime(microsecs):Thisreportprovidesaflatviewoftherawprofilerdata.Itincludesthetotalcallcount,selftime,subtreetime,anddescendantsofeachfunction.FunctionElapsedTime(microsecs)DatasortedbyTotalFunctionElapsedTime(microsecs):Thismodule-levelsummaryreportshowsthetotaltimespentineachmoduleandthetotalcallstothefunctionsinthemodule.NamespaceElapsedTime(microsecs)DatasortedbyNamespace:ThisreportprovidesthedistributionoftimespentbythePL/SQLandSQLengines.SQLandPL/SQLarethetwonamespacecategoriesavailableforablock.ItisveryusefulinreducingthediskI/Oandhenceenhancingblockperformance.Thenetsumofthedistributionisalways100percent.

SummaryInthischapter,welearnedvarioustechniquestomaintainPL/SQLprogramcode.AskillinanalyzingaPL/SQLprogramisrequiredinordertotroubleshootcodeissuesordiagnoseperformancebottlenecks.Therearemanydictionaryviewsthatcanprovidelotofmetadataaboutaprogram,butdevelopersneedtopicktherightoneforthejob.Tracingandprofilingarethetechniqueswithwhichdatabasedevelopersshouldbefamiliar.Inlargescaledevelopments,tracingandprofilingcanbeofgreathelpinidentifyingopportunitiestoimproveperformance.

Inthenextchapter,wewilldiscusshowtosafeguardyourdatabaseapplicationsagainstSQLinjectionattacks.

PracticeexerciseWhichofthefollowingdictionaryviewsisusedtogetinformationaboutsubprogramarguments?

1. ALL_OBJECTS2. ALL_ARGUMENTS3. ALL_DEPENDENCIES4. ALL_PROGRAMS

Thetablespaceinformationonadatabaseserverisasfollows:

SELECTtablespace_name

FROMDBA_TABLESPACES

/

TABLESPACE_NAME

----------------

SYSTEM

UNDOTBS1

TEMP

USERS

EXAMPLE

Youexecutethefollowingcommandinthesession:

SQL>ALTERSESSIONSETPLSCOPE_SETTINGS='IDENTIFIERS:ALL';

Sessionaltered.

Identifythecorrectstatements:

1. TheidentifierinformationwouldbecapturedbyPL/Scopefortheprogramcreatedorcompiledinthesession.

2. TheidentifierinformationwouldnotbecapturedbyPL/ScopeasIDENTIFIERS:ALLcanbeenabledonlyattheSYSTEMlevel.

3. TheidentifierinformationwouldbecapturedbyPL/Scopeonlyfortheprogramsthatarecreatedinthesession.

4. TheidentifierinformationwouldnotbecapturedbyPL/ScopesincetheSYSAUXtablespaceisnotavailable.

TheparametersspecifiedinDBMS_METADATAarecase-sensitive:

1. True2. False

DBMS_UTILITY.FORMAT_CALL_STACKaccomplisheswhichofthefollowingobjectives:

1. CapturesexceptionsinaPL/SQLblock.2. Preparesthestackofsequentialcalls.3. Preparesthestackofexecutionactions.

4. Preparesthestackofblockprofiler.

WhichofthefollowingdoestheDBMS_METADATApackageachieve:

1. Generatesreportofinvalidatedobjectsinaschema.2. GeneratesDDLforagivenorallobject(s)inaschema.3. Generatesanobject-to-tabledependencyreportinaschema4. Generatesareportofobjectstatisticsinaschema

ThePL/ScopetoolcanstoreidentifierdataonlyintheUSERStablespace.

1. True2. False

WhichofthefollowingarethevalidparametervaluesofSET_TRANSFORM_PARAMfortablesalone?

1. STORAGE2. FORCE3. PRETTY4. INHERIT

Chapter11.SafeguardingPL/SQLCodeagainstSQLinjectionAnincidenceofasecuritybreachinvolves:ahackerandavulnerablesystem.Ahackercanbeaninsideroranoutsider,whoattacksthesystemtoexposeandaccessconfidentialinformation,whichmayleadtofatalconsequences.Asystemcouldbevulnerabletoattacksbecauseoflowcodingstandardsandahalf-bakedunderstandingoftechnologies.Thesteepgrowthofwebapplicationusersandsharpriseinsocialmediainteractionshaswidenedtheattacksurfacearea.Thesystemsthatareahacker’sparadisearethosewhichcontainpersonalidentifiableinformation,financialinformation,governmentdata,andbusinesstransactions.Thehazardousconsequencesofasecuritybreachhavepushedmanyorganizationstolookseriouslyafterdatasecurity.Asafirstlayerofprotection,organizationsmustboltthenetworkpenetrationthroughtheadoptionofproductslikeAuditVaultandDatabaseFirewall(AVDF)andprotectdataaccessthroughstrongdataaccesspolicies,encryptionorredaction.

SQLinjectionisatechniquetobreakthroughtheapplicationdesignandextractsensitivedata.In1998,anauthorbypennameRainForestPuppy(rfp)firstidentifiedthetechnologyvulnerabilitiesinhispaperNTWebTechnologyVulnerabilitiesforPhrackmagazineandevangelizedthebestpracticesofwritingcodetodilutesuchacts.Thechapteroutlineisasfollows:

WhatisSQLinjection?PreventingSQLinjectionattacksTestingthecodeforSQLinjectionflaws

WhatisSQLinjection?AdatabaseapplicationontheserversidecontainstheprogrammablelogicembeddedwithinthePL/SQLpackagesandsubprograms.ThesePL/SQLprogramunitsmaycontainSQLstatements,whichareintendedtoperformspecificoperations.TheSQLstatements,whosequerytextisbuiltatruntime(dynamicallyderived)andbasedonclient-suppliedinputs,openwaysforSQLinjection.AmalicioususercansupplyamanipulatedinputthatcanbreakthroughthePL/SQLprogramlogicbyreplacingtheSQLsyntaxandperformarbitraryexecution.

ThereasonitisknownasInjectionisbecausethemanipulatedtext,whichreplacesorappendstotheoriginalSQLtextinaPL/SQLprogramunit,isparsedalongwiththeoriginalSQLstatement.Theundetectedattacker’scodeislegallyexecutedbytheSQLengine,alongwiththeoriginalprogrammedSQL.

Forexample,astringtypemaliciousinputfromtheclientisexecutedaslegalcodebytheSQLengine;thus,exploitingaserver-sideSQLstatement.Asaconsequence,anattackercangainaccesstosensitiveandrestrictedinformationfromthedatabase.Thedata,consideredtobeattack-prone,canbepersonalinformation,creditcardinformation,anorganization’sinternaldata,orgovernmentdata.

Althoughtherearemultipleplatformtargets,techniquesandremediesforSQLinjection,thischapterrestrictsthescopeofdiscussiontotheattacksonPL/SQLunitswiththebestpracticestoavoidthem.

SQLinjectiontargetsInmanyofthecasesreportedtodate,theclient-suppliedinputswereidentifiedasthemajorcauseofSQLinjectionattacks.ThedynamicSQL,whichworksdirectlywiththeclient-suppliedinputs,ismorepronetoinjectionattacks.Afterthecodevulnerabilitiesarediscovered,anattackercanexploitthecodetoanyextent.Byextractingrestricteddata,theycanupdateordeletesensitiveinformation.Notonlythedatamodification,datadefinitionscanalsobemodifiedthroughSQLinjection.

Apartfromtheclient-suppliedinputs,adefinerPL/SQLprogramunitcanindirectlyleadtocodeinjectionbecauseitexecuteswiththeprivilegesoftheunitownerandnottheinvoker.Therefore,aninvokercanexecuteaPL/SQLprogramwithanelevatedsetofprivileges.

HowtoexploitthePL/SQLcode?TherearenumerousformsofSQLinjection.AnattackercancreateafunctiontoupdatesensitiveinformationwithPRAGMAAUTONOMOUS_TRANSACTION.HecangainaccesstotheDBAprivilegesandmakeirrevocablechangestothedatabase.

Let’sunderstandtheSQLinjectionthroughacreditcardcasestudy.ThefollowingCREATETABLEstatementcreatesanEMP_CREDIT_BALtable,whichcontainsthecreditcarddetailsofemployees:

/*Testtabletogeneratecreditcarddetailsofemployees*/

CREATETABLEemp_credit_bal

AS

SELECTempnocard_holder,

deptno,

ename,

job,

sal,

REGEXP_REPLACE(str,'(\d{4})(\d{4})(\d{4})(\d{4})','\1-\2-\3-\4')card_no,

TRUNC(DBMS_RANDOM.VALUE(sal,5*sal))credit_balance

FROMempE,

(SELECTTO_CHAR(

TRUNC(

DBMS_RANDOM.VALUE(1000000000000000,

9999999999999999)))str

FROMdual

)

/

/*Verifythedatainthetable*/

SELECTename,

card_no,

credit_balance

FROMemp_credit_bal

/

ENAMECARD_NOCREDIT_BALANCE

--------------------------------------------

SMITH4020-3009-1084-03452844

ALLEN9205-3519-4278-79932034

WARD7838-5801-5970-80604038

JONES7556-7454-2248-08504336

MARTIN6689-9703-5168-52821690

BLAKE3662-7700-4489-31875443

CLARK6195-2171-8232-324011152

SCOTT1961-7153-0620-936614337

KING7930-1567-7029-094319497

TURNER8166-4431-5647-35792286

ADAMS8155-2229-9107-36342301

JAMES4788-5716-1863-69831540

FORD8683-1130-1302-14989750

MILLER5522-2843-9553-51883585

14rowsselected.

AP_REP_CC_BALprocedureisalowstandardprogramthatacceptsthelastfourdigitsofthecreditcardandprintsthecreditbalancereportoftheemployee:

/*Proceduretoprintthecreditcardinfoofacardholder*/

CREATEORREPLACEPROCEDUREp_rep_cc_bal(p_card_noVARCHAR2)

IS

/*Declarerefcursorvariable*/

TYPEc_refISREFCURSOR;

cc_balC_REF;

/*DeclarearecordofEMP_CREDIT_CARDrowtype*/

emp_cc_recemp_credit_bal%rowtype;

BEGIN

/*OpentherefcursorvariableforaSELECTquery*/

OPENcc_balFOR'SELECT*FROMemp_credit_bal

WHEREsubstr(card_no,-4,4)='||p_card_no;

LOOP

/*Iteratethroughtheresultsettofetchtherecord*/

FETCHcc_balINTOemp_cc_rec;

EXITWHENcc_bal%NOTFOUND;

/*Printthecreditcardinformation*/


DBMS_OUTPUT.PUT_LINE('EmpName/Title:'||emp_cc_rec.ename||'|

'||INITCAP(emp_cc_rec.job));

DBMS_OUTPUT.PUT_LINE('EmpCCard:'||emp_cc_rec.card_no);

DBMS_OUTPUT.PUT_LINE('CCardBalance:'||emp_cc_rec.credit_balance);

ENDLOOP;

CLOSEcc_bal;

END;

/

/*EnabletheSERVEROUTPUTtoprinttheprogramoutput*/

SETSERVEROUTPUTON

Let’stesttheprecedingprocedurewithasampleinput:

EXECp_rep_cc_bal('0345');

__________________________________________________

EmpName/Title:SMITH|Clerk

EmpCCard:4020-3009-1084-0345

CCardBalance:2844


Let’scheckhowahackercantweakthestringinputtoextractthedetailsofthePRESIDENT:

EXECp_rep_cc_bal('''XXX''ORJOB=''PRESIDENT''');

__________________________________________________

EmpName/Title:KING|President

EmpCCard:7930-1567-7029-0943

CCardBalance:19497


Whatwehavejustseenishowamanipulatedinputbypassestheprocedurallogicbysupplyingamanipulatedvaluetotheexistingpredicate(s).ItappendsanewpredicatetotheSQLthatfetchesthepresident’screditdetails.Thefollowingprocedurecallfetchesthecreditcarddetailsofemployeesfromdepartment10:

EXECp_rep_cc_bal('''XXX''ORDEPTNO=10');

__________________________________________________

EmpName/Title:CLARK|Manager

EmpCCard:6195-2171-8232-3240

CCardBalance:11152

__________________________________________________


EmpCCard:7930-1567-7029-0943

CCardBalance:19497

__________________________________________________

EmpName/Title:MILLER|Clerk

EmpCCard:5522-2843-9553-5188

CCardBalance:3585


Likewise,anattackercangeneratethereportforalltheemployeesbybypassingallthefiltersandpredicates:

EXECp_rep_cc_bal('''XXX''OR1=1');

__________________________________________________


EmpCCard:4020-3009-1084-0345

CCardBalance:2844

__________________________________________________

EmpName/Title:ALLEN|Salesman

EmpCCard:9205-3519-4278-7993

CCardBalance:2034

__________________________________________________

EmpName/Title:WARD|Salesman

EmpCCard:7838-5801-5970-8060

CCardBalance:4038

__________________________________________________

EmpName/Title:JONES|Manager

EmpCCard:7556-7454-2248-0850

CCardBalance:4336

__________________________________________________

EmpName/Title:MARTIN|Salesman

EmpCCard:6689-9703-5168-5282

CCardBalance:1690

__________________________________________________

EmpName/Title:BLAKE|Manager

EmpCCard:3662-7700-4489-3187

CCardBalance:5443

__________________________________________________

EmpName/Title:CLARK|Manager

EmpCCard:6195-2171-8232-3240

CCardBalance:11152

__________________________________________________

EmpName/Title:SCOTT|Analyst

EmpCCard:1961-7153-0620-9366

CCardBalance:14337

__________________________________________________


EmpCCard:7930-1567-7029-0943

CCardBalance:19497

__________________________________________________

EmpName/Title:TURNER|Salesman

EmpCCard:8166-4431-5647-3579

CCardBalance:2286

__________________________________________________

EmpName/Title:ADAMS|Clerk

EmpCCard:8155-2229-9107-3634

CCardBalance:2301

__________________________________________________

EmpName/Title:JAMES|Clerk

EmpCCard:4788-5716-1863-6983

CCardBalance:1540

__________________________________________________

EmpName/Title:FORD|Analyst

EmpCCard:8683-1130-1302-1498

CCardBalance:9750

__________________________________________________

EmpName/Title:MILLER|Clerk

EmpCCard:5522-2843-9553-5188

CCardBalance:3585


Now,youcanrealizehowthegoodoldargumentscanbeexploitedtoleakconfidentialinformation.Abadlycodedprocedure,whichisnottoouncommon,isvulnerabletosuchattacks.

TheprecedingcasestudyisaclassicexampleofaFirstOrderAttack,wherethedatalosesitsconfidentialityafteritisattacked.Ifthedataattackdoesnothappenthroughprogramexecution,itiscalledaSecondOrderAttack.

ThefollowingdiagrambranchestheimpactsofSQLinjection:

TheimpactofSQLinjection

PreventingSQLinjectionattacksSQLinjectionisnotadesignbug,butanintentionalmaliciouspractice.DatabasedevelopersmustadoptbestpracticeswhilewritingPL/SQLcode.Ifcodemodificationisnotpossible,theapplicationinterfacelayermayalsoworktoreducetheattacksurfacearea.

Let’stakeabrieflookattheprecautionarymeasurestominimizeinjectionattacks:

CheckyourdynamicSQL:DynamicSQLquerytext,whichisconstructedatruntimeanddirectlyusestheuser-suppliedinputs,createsapregnablehitchpointintheapplication.Youcanprotectthemagainstinjectionattacksthrougheitherofthesetechniques:

ReducethedirectexposureofclientinputstodynamicSQL:Youcansanitizeandvalidatetheclient-suppliedinputsbeforetheyareusedindynamicSQL.OracleprovidestheDBMS_ASSERTpackagetoverifytheinputs.UsebindargumentsindynamicSQL:Databasedevelopersareencouragedtomakeuseofbindargumentsformultiplereasonsandoneofthemissecurity.Bindargumentsnearlyeliminatethepossibilityofattacks.Manipulatedargumentvalueswouldendinanexception,therebyterminatingtheprogramexecution.

Monitorauser’sobjectprivileges:Irregularityinobjectprivilegescanbeapotentialthreattoanapplication.Ausercaninvokeadefiner’sprogramunitwhichmaybeatahigherprivilegelevel.Fromasecuritystandpoint,auseratalowerprivilegelevelcangainaccesstounauthorizeddatasetsobjects.Theuseoftheinvoker’sprogramunitsshouldbeencouragedtoregulateobjectprivileges.OracleDatabase12cenhancesthesecurityofthedefiner’sprogramunitsbyallowingthegrantingofrolestoprogramunits.

SanitizinginputsusingDBMS_ASSERTOracle10gRelease2introducedtheDBMS_ASSERTpackagetovalidateuserinputsbeforetheyareconsumedbytheserver-sideprogramunits.Thepackageassertsorpostulatesaninputforacertainfactsuchasquotedandunquotedidentifiers,orobjectvalidity,andsoon.Uponassertion,theinputisreturnedastheactualinstance.Iftheassertionfails,theVALUE_ERRORexceptionwillberaised.

TheDBMS_ASSERTpackageisownedbySYSandcontainssevenpackagedfunctions.Thepackagesubprogramsaredemonstratedasfollows:

Subprograms Description

ENQUOTE_LITERALfunction Enclosesastringliteralwithinsinglequotes

ENQUOTE_NAMEfunction Enclosestheinputstringindoublequotes

NOOPfunctions Anoverloadedfunctionreturnsthevaluewithoutanychecking;doesnooperation

QUALIFIED_SQL_NAMEfunction VerifiesiftheinputstringisaqualifiedSQLnameRaisesORA-44004iftheinputstringisnotavalidqualifiedSQLname

SCHEMA_NAMEfunction VerifiesiftheinputstringisavalidschemanameRaisesORA-44001iftheinputstringisaninvalidschemaname

SIMPLE_SQL_NAMEfunction Verifiesiftheinputstringisasimpleidentifier(quotedandunquoted)RaisesORA-44003iftheinputstringisaninvalidSQLname

SQL_OBJECT_NAMEfunction VerifiesiftheinputparameterstringisavalidobjectinthedatabaseRaisesORA-44002iftheinputstringisaninvalidobjectname

ChoosetherightsubprogramfortherightidentifierTheDBMS_ASSERTsubprogramaimstoverifythepropertiesofidentifiersandliterals.Anidentifierisusedtodenoteeachandeveryitemusedinthedatabase.AlltheobjectnamesorvariablenamesinaPL/SQLblockareidentifiers.Anidentifiercanbequoted,unquoted,orliteral.

Unquotedidentifiers

ThisidentifierabidesbythenamingconventionoftheOracleDatabase:itmustbeginwithanalphabetfollowedbynumbersorasetofdefinedspecialcharacters(_).Theverificationalgorithmofunquotedidentifiersisbasicanditcheckswhethertheidentifierfollowsapropernamingconvention.

YoucanuseSIMPLE_SQL_NAMEtocheckwhetheranunquotedidentifiercontainsanynonadmissiblecharactersandstartswithanalphabet.Notethatitdoesn’tverifythevaliditystatusoftheinputidentifier.

Inthefollowingexample,SIMPLE_SQL_NAMEconfirmstheinputidentifierasitcorrectlyfollowsthenamingconvention:

/*VerifyanunquotedidentifierusingSIMPLE_SQL_NAME*/

SELECTDBMS_ASSERT.SIMPLE_SQL_NAME('emp_credit_bal')

FROMDUAL

/

DBMS_ASSERT.SIMPLE_SQL_NAME('EMP_CREDIT_BAL')

-----------------------------------------------

emp_credit_bal

Anyviolationinthenamingconventionwouldthrowanexception:

/*VerifyanunquotedidentifierusingSIMPLE_SQL_NAME*/

SELECTDBMS_ASSERT.SIMPLE_SQL_NAME('1emp_credit_bal')

FROMDUAL

/

*

ERRORatline1:

ORA-44003:invalidSQLname

ORA-06512:at"SYS.DBMS_ASSERT",line206

AnidentifierwithmorethanoneSQLnameshouldbevalidatedthroughQUALIFIED_SQL_NAME.Aqualifiermayincludeaschemaname,anobjectname,oradatabaselink:

/*VerifyanunquotedqualifierusingSIMPLE_SQL_NAME*/

SELECTDBMS_ASSERT.SIMPLE_SQL_NAME('scott.emp_credit_bal')

FROMDUAL

/

SELECTDBMS_ASSERT.SIMPLE_SQL_NAME('scott.emp_credit_bal')FROMDUAL

*

ERRORatline1:



/*VerifyanunquotedqualifierusingQUALIFIED_SQL_NAME*/

SELECTDBMS_ASSERT.QUALIFIED_SQL_NAME('scott.emp_credit_bal')FROMDUAL

/

DBMS_ASSERT.QUALIFIED_SQL_NAME('SCOTT.EMP_CREDIT_BAL')

---------------------------------------------------------

scott.emp_credit_bal

SchemanamesandobjectnamescanbedistinctlyverifiedusingtheSCHEMA_NAMEandSQL_OBJECT_NAMEsubprogramsofDBMS_ASSERT.Forexample,thefollowingSELECTqueryverifiestheschemanameandobjectnamebeforesanitizingthequalifier:

/*VerifyanunquotedqualifierusingQUALIFIED_SQL_NAME*/

SELECTDBMS_ASSERT.QUALIFIED_SQL_NAME(

DBMS_ASSERT.SCHEMA_NAME('SCOTT')||'.'||

DBMS_ASSERT.SQL_OBJECT_NAME('emp_credit_bal'))obj

FROMDUAL

/

OBJ

------------------------

SCOTT.emp_credit_bal

TipSCHEMA_NAMEisacase-sensitivesubprogram.Alowercasestringinputwillnotbeverifiedasaschemaname.

Quotedidentifiers

Aquotedidentifierisalwaysenclosedwithindoublequotesandfollowsnonamingconvention.Itmaystartwithanumberorevencontainanyspecialcharacter.YoucanuseSIMPLE_SQL_NAMEtocheckthesanityofquotedidentifiers:

/*Unquotedidentifierwithspecialcharactersraiseexception*/

SELECTDBMS_ASSERT.SIMPLE_SQL_NAME('***emp_credit_bal***')

FROMDUAL

/

ERRORatline1:



/*Quotedidentifierwithspecialcharactersreturnvalue*/

SELECTDBMS_ASSERT.SIMPLE_SQL_NAME('"***emp_credit_bal***"')FROMDUAL

/

DBMS_ASSERT.SIMPLE_SQL_NAME('"***EMP_CREDIT_BAL***"')

--------------------------------------------------------------

"***emp_credit_bal***"

YoucanalsousetheENQUOTE_NAMEsubprogramtoencloseaconstantvalueoridentifierindoublequotes.Quotedidentifiers,whicharequalifiers,canbeverifiedusingtheQUALIFIED_SQL_NAMEsubprogram.

NoteTheOracle-suppliedDBMS_UTILITY.NAME_TOKENIZEsubprogramhelpsindifferentiatingasimpleSQLnamefromaqualifiedSQLname.

Literals

AliteralcanbeanyfixedconstantusedinaSQLqueryoraPL/SQLprogram:

/*DemonstratetheuseofaliteralinaSELECTquery*/

SELECT*

FROMemp

WHEREename='KING'

/

/*Use(EMP)asaliteral*/

SELECT*

FROMuser_tables

WHEREtable_name='EMP'

/

Whileworkingwithliterals,youcanuseENQUOTE_LITERALtosanitizetheclient-suppliedinputsandavoidadditionalpredicatesortheunionSELECTquery.Let’slookatauserinputthatwasusedearliertoinjectandextractthecreditcardinformationofemployees:

/*Sanitizetheinputbeforesupplyingittoprocedurecall*/

DECLARE

l_ccVARCHAR2(4000):='''XXX''ORDEPTNO=10';

BEGIN

/*SanitizeusingDBMS_ASSERT*/

l_cc:=DBMS_ASSERT.ENQUOTE_LITERAL(l_cc);

p_rep_cc_bal(l_cc);

END;

/

DECLARE

*

ERRORatline1:




ORA-06512:atline4

TheprecedingblockthrowsanexceptionbecausetheclientinputcouldnotbeverifiedbytheDBMS_ASSERTpackage.

DBMS_ASSERT–limitationsThelimitationsoftheDBMS_ASSERTpackagearelistedasfollows:

NovalidationfortheTNSconnectionstrings.Novalidationforstringlengthsorbufferoverflowattacks.NovalidationforthevalidityofSQLidentifiers.Novalidationforobjectprivilegesortheunintendeduseofprivileges.Forprivilegeevaluation,youcanusetheOracleDatabase12cprivilegeanalysisfeaturetodeterminewhethertoretainorrevokeobjectprivileges.

UseofbindvariablestopreventinjectionattacksUsingbindvariablesisagoodprogrammingpractice.Fromaperformancestandpoint,bindvariableseliminatehardparsesofSQLstatementsandimprovetheperformanceofaPL/SQLblock.Fromasecuritystandpoint,abindvariableavoidstheconcatenationofliteralvaluestoadynamicSQLstatement.

Let’srevisitthecreditcardcasestudyandrewritetheprocedurewiththehelpofbindvariables.NotetheuseoftheB_CARD_NObindvariableintherefcursor:

/*Re-writetheprocedureP_REP_CC_BALtousebindvariables*/

CREATEORREPLACEPROCEDUREp_rep_cc_bal(p_card_noVARCHAR2)

IS

/*Declarerefcursorvariable*/

TYPEc_refISREFCURSOR;

cc_balC_REF;

/*DeclarerecordstructureofEMP_CREDITBALrowtype*/

emp_cc_recemp_credit_bal%rowtype;

BEGIN

/*Opentherefcursorvariablewithabindvariable*/

OPENcc_balFOR'SELECT*FROMemp_credit_bal

WHEREsubstr(card_no,-4,4)=:b_card_no'

USINGp_card_no;

LOOP

/*Iteratetheresultsetandprintthecreditcardinfo*/

FETCHcc_balINTOemp_cc_rec;

EXITWHENcc_bal%NOTFOUND;


DBMS_OUTPUT.PUT_LINE('EmpName/Title:'||emp_cc_rec.ename||'|

'||INITCAP(emp_cc_rec.job));

DBMS_OUTPUT.PUT_LINE('EmpCCard:'||emp_cc_rec.card_no);

DBMS_OUTPUT.PUT_LINE('CCardBalance:'||emp_cc_rec.credit_balance);

ENDLOOP;

CLOSEcc_bal;

END;

/

SETSERVEROUTPUTON

Youcanchecktheprocedureoutputwithatestinput:

/*VerifywithInput-1*/

EXECp_rep_cc_bal('0345');

__________________________________________________


EmpCCard:4020-3009-1084-0345

CCardBalance:2844


Let’sinvoketheprocedurewiththemanipulatedinputs,whichwereearlierusedtoaccess

restricteddata:


EXECp_rep_cc_bal('''XXX''ORJOB=''PRESIDENT''');



EXECp_rep_cc_bal('''XXX''ORDEPTNO=10');



EXECp_rep_cc_bal('''XXX''OR1=1');


Well,noneofthemreturnedanoutput,becausethebindvariablevalueorthetweakedinputdidn’tcreateavalidSQLcursor.Therefore,itcouldnotbeexecuted.

BestpracticestoavoidSQLinjectionTherearemultiplebestpracticestomitigatetheeffectofSQLinjection.Theobjectiveofthesebestpracticesistoreducetheattacksurfaceareabycoveringthevulnerableareasofthedatabasecode.Thelistedbestpracticesaresafetofollowandeasytoremember:

AvoiddynamicallyconstructedSQLquerytextinthePL/SQLprogramunits.UsestaticSQLwhereverpossible,asitavoidsthecodevulnerability.WithdynamicSQL,bindvariablesshouldbeused.ExposedatabaseprogramunitstotheclientthroughtheAPIunitsonly.MonitorandcontroltheobjectprivilegescarefullybeforegrantingtheEXECUTEprivilegeonanobjecttoauser.EncouragetheuseoftheDBMS_ASSERTsubprograminpolicing;notjustforuserinputs,butalsodynamicSQLtextsandplaceholdervaluesinaSQLstatement.Applicationclientscanalsoprogrammaticallyrestrictarbitraryinputsandallowonlytheexpectedones.ExamineandevaluatetheuseofPUBLICprivileges.Encouragetheadoptionofdatasecuritysolutionssuchasencryption,dataredaction,databasevault,auditvault,anddatabasefirewall.

TestingthecodeforSQLinjectionflawsSofar,wehavediscussedthesymptomsandremediesofSQLinjection.Wedemonstratedtheprogrammingrecommendationstomitigatetheeffectsofcodeinjectionsandsmuggles.Assuringcodequalityduringthetestingcycleplaysacrucialroletowardspreventingcodeattacks.Thecodetestingresourcesmustadoptaconcretestrategytodiscoverandhituponthecode’svulnerabilitiesbeforeitinvitesanattackertoexploitthedatabase.Now,wewilldiscusssomeofthetestingconsiderationstotestthecodeforSQLinjectionflaws.

TeststrategyAlogicalandefficientteststrategymustbeemployedtodiscoverinjectionflaws.Ofcourse,thereisnomagicbullettofilteroutallthevulnerabilitiesofapieceofcode.

Usualcodereviewsareapartofstatictestingwhiletestingprogramswithsampledataandinputscomeunderdynamictesting.Thesedays,statictestinghasbeenabsorbedintothedevelopmentstage,wheredevelopersandtheirpeersandseniorsreviewthecode.Majorsyntacticalerrors,logicalissues,codepractices,andinjectionbugscanbetracedatthislevel.TheDryRunconceptcanevencheckmultiplescenariosandensurebug-freeapplicationsubmissiontothequalityassuranceteam.

AneffectivecodereviewAsacodereviewer,thefirstandforemoststepistomeasuretheattacksurfacearea.Thecodereviewermustverifytheexposureofthedatabaseprogramunitsintheapplicationinterfacelayer.Inaddition,theymustchecktheprivilegesavailabletothedatabaseusers.Oncethesestepsarepassedwiththerightjustification,thePL/SQLcodecanbereviewedtoidentifythevulnerableareas.InPL/SQL-basedapplications,alwaysbecarefultolookfor:

DynamicSQLusing:

EXECUTEIMMEDIATEREFCURSORqueriesDBMS_SQL

DBMS_SYS_SQL

CheckfortheappropriateusageofbindargumentsParametersanitizationusingDBMS_ASSERT

Similarly,inaJavaorCclientarchitecture,thereviewermustlookfordynamiccallablestatementpreparation.

StaticcodeanalysisSQLinjectionattacksaremostlyduetocodingunawarenessanddynamicSQL.Therefore,staticcodeanalyzerscannoteasilytraceanapplication’svulnerability.TheOracledocumentationdefinesstaticcodeanalysisasfollows:

Staticcodeanalysisistheanalysisofcomputersoftwarethatisperformedwithoutexecutingprogramsbuiltfromthatsoftware.Inmostcases,theanalysisisperformedonsomeversionofthesourcecodeandinothercases,someformoftheobjectcode.Thetermisusuallyappliedtotheanalysisperformedbyanautomatedtool.

Itisadvisablethatsuchanalysistoolsshouldnotbeconsideredasthetestingbenchmarkandconfirmatorytools.Instead,theycanbeusedforwhiteboxtesting,wheretheapplicationistestedforasmoothlogicalflowandtheprogramexecutionsfordifferentnatureofinputdata.

FuzztoolsFuzztestingisaroughtestingthatisnotbasedonanypresetlogicorusecase.Itmeasurestheapplication’ssustainabilityagainstjunkandmaliciousinputs.Withoutanypreconceptionofthesystemorprogrambehavior,itusesrawinputstochecktheprogramsemantics.Theenvironmentforfuzztestingtoolscanbeexplicitlymadebymodifyingthecontextvaluesandmanipulatingthetestdatatoallodds.

Thebugsreportedinfuzztestingmaynotalwaysberealthreatstotheapplication,buttheymayprovideacluetothevulnerabilityattacks.

GeneratingtestcasesThelastandthefinalcallisthepreparationoftestcases.Althoughthisisskippedduringthedevelopmentstage,thetestcasesserveastheproofoftestingatlaterstages.Testcasescanmeasuretherobustnessofdatabaseprograms,applicationsecurity,andthevalidationofclientinputs.

SummaryInthischapter,welearnedaboutamalicioushackingconcept—SQLinjection.Wediscussedthecausesofacodeattackanditsimpactonthedatabase.Wecoveredthetechniquestosafeguardanapplicationagainsttheinjectionattacksthroughdemonstrationsandillustrations.Attheendofthechapter,wediscussedsomeofthetestingconsiderationstoexposethevulnerableareasinthecode.

PracticeexerciseWhichmethodwouldyouemploytoprotectthePL/SQLcodeagainstSQLinjectionattacks?

1. ReplaceDynamicSQLswithStaticSQLs.2. ReplaceconcatenatedinputsinDynamicSQLwithbindarguments.3. DeclarethePL/SQLprogramtobeexecutedbyitsinvoker’srights.4. Removestringtypeparametersfromtheprocedure.

YoushouldusestaticSQLtoavoidSQLinjectionwhenallOracleidentifiersareknownatthetimeofcodeexecution.

1. True.2. False.

ChoosetheimpactofSQLinjectionattacks:

1. Maliciousstringinputscanextractconfidentialinformation.2. Unauthorizedaccesscandropadatabase.3. ItcaninserttheORDERdataintotheEMPLOYEEStable.4. Aprocedureexecutedbyowners,(SYS)rightscanchangethepasswordofauser.

PickthecorrectstrategiestofightagainstSQLinjection:

1. SanitizethemaliciousinputsfromtheapplicationlayerwithDBMS_ASSERT.2. RemovestringconcatenatedinputsfromtheOraclesubprogram.3. DynamicSQLshouldberemovedfromthestage.4. ExecuteaPL/SQLprogramwithitscreator’srights.

Statisticalcodeanalysisprovidesanefficienttechniquetotracetheapplication’svulnerabilitybyusingidealandexpectedparametervalues.

1. True.2. False.

Thefuzztooltechniqueisaharshandrigorousformatoftestingwhichusesrawinputsandchecksaprograms’sanctity.

1. True.2. False.

ChoosetheobjectivesthatcanbeaddressedbytheDBMS_ASSERTpackagetopreventSQLinjection

1. Encloseagivenstringinsinglequotes.

2. Encloseagivenstringindoublequotes.3. Verifyaschemaobjectname.4. VerifyasimpleSQLandqualifiedSQLidentifier.

IdentifythenatureofthetablenameinthefollowingSELECTstatement:

SELECTTOTAL

FROM"ORDERS"

WHEREORD_ID=P_ORDID

/

1. Aunquotedidentifier.2. Aquotedidentifier.3. Aliteral.4. Aplaceholder.

WhichofthefollowingDBMS_ASSERTsubprogramsmodifiestheinputvalue?

1. SIMPLE_SQL_NAME.2. ENQUOTE_LITERAL.3. QUALIFIED_SQL_NAME.4. NOOP.

ThecodereviewsmustidentifycertainvulnerablekeyareasforSQLinjection.Selectthecorrectonesfromthefollowinglist:

1. DBMS_SQL.2. BULKCOLLECT.3. EXECUTEIMMEDIATE.4. REFCURSOR.

TheAUTHIDCURRENT_USERclauseachieveswhichofthefollowingpurposes?

1. Thecodeexecuteswiththeinvoker’srights.2. Thecodeexecuteswiththecurrentloggedinuser.3. IteliminatesSQLinjectionvulnerabilities.4. Thecodeexecuteswiththecreator’srights.

Chapter12.WorkingwithOracleSQLDeveloperSQLDeveloperisanintegrateddevelopmentenvironmentfromOraclethatservesasaone-stopsolutionformajorOracleDatabaseactivities,therebystandardizingthedevelopmenttasksandenhancingtheproductivityofdatabaseprofessionals.Asafreegraphicaluserinterface(GUI)tool,SQLDeveloperoffersawidesetoffeaturesandsolutionsfordatabasedevelopment,administration,andmanagement,inon-premiseandclouddeployments.TheSQLDevelopertoolsupportsOracleDatabase10g,11g,and12c.

Fordatabasedevelopers,SQLDeveloperoffersricheditorsforworkingwithcoreandadvancedfunctionalities,suchasexecute,debug,andtest,usingSQL,PL/SQL,XML,StoredJavaprocedures,querytuning,andmuchmore.DatabaseadministratorscanuseSQLDevelopertoperformvariousoperationslikedataexportandimportviadatapump,databasebackupandrecoverytasksviaRMAN,resourcemonitorandmanagement,performanceanalysisanddiagnosis,usedatamodelerandthird-partymigration.

Inthischapter,wewilldescribethebenefitsofSQLDeveloper,fordatabaseadministrators,andarchitects.Notethatthechapterdoesnotintendtoprovideastep-by-steptutorialforvarioustooloperations.Theoutlineofthechapterisasfollows:

OverviewofSQLDeveloper

KeydifferentiatorsHistoryandbackgroundSQLDeveloperforDBASQLDeveloperforDevelopers

GettingstartedwithSQLDeveloperNewfeaturesofSQLDeveloper4.0and4.1

AnoverviewofSQLDeveloperSQLDeveloperisafreeintegrateddevelopmentenvironmentfromOraclethatallowsthedatabasecommunitytodevelopPL/SQLapplicationsand,performadministrativetasks,andenablesmanagementactivitiessuchasdatamodeling,versioning,scripting,andthird-partymigration.ThelatestversionofSQLDeveloper(asofthetimeofwritingthisbook)is4.1.1.

ThetoolisbuiltusingJava(onJDeveloperFramework),whichenablesittorunonWindows,Linux,andMacOSX.Bydefault,itusesthethinJDBC(TypeIVJavadriver)drivertoconnecttothedatabase,thusreducingtherequirementsofanyfurtherdatabaseclients.Inaddition,theextensiblearchitectureofSQLDeveloperallowsthedevelopercommunitytoincorporatetheirowncustomextensionsintothetool.YoucanleverageOracleJDeveloper’sExtensionSDK(SoftwareDevelopmentKit)todevelopandaddtherequiredfunctionalityasanextensiontotheSQLDevelopertool.

TipVisittheSQLDeveloperExtensionsExchange(http://www.oracle.com/technetwork/developer-tools/sql-developer/extensions-083825.html)tolookforextensionsthatwerebuiltwithinandoutsideOracle.

http://www.oracle.com/technetwork/developer-tools/sql-developer/extensions-083825.html

KeydifferentiatorsThefollowingarethekeyfactorsthatdifferentiateSQLDeveloperfromothercontemporarytools:

SQLDeveloperisafreetoolandshippedalongwiththeOracleDatabasesoftware.Noseparateinstallationisrequired.OraclesupportisavailableforthecustomerswhohavelicensedtheOracleDatabase.Itsupportstraditionalon-premiseaswellasclouddeploymentsofOracleDatabase.ItsupportsdatabaseproductssuchasDataMiner,TimesTen,Spatial,andGraph.Itisdeveloper-richandadministrator-friendlytoo.TheDBAconsoleprovidesawidesetoffeaturesforadministrativetasks.Therearepre-builtreportsforprovidinginformationaboutthedatabasemanagement,databaseschemas,andperformance.Thereisprovisionforcreatingcustomreportsandcreatingmultilevelwithpredefinedreports.Thereislogical,relational,andphysicalmodellingenabledthroughtheDataModelerextension.IthastheabilitytoconnecttonotjusttheOracleDatabase,butalsonon-OracledatabasessuchasSQLserver,Sybase,andDB2.BuildontheJDeveloperframework.Thereisprovisionforincludingcustom-builtextensionsinthetool.ThereisawidecommunityofSQLDeveloperuserswhointeractthroughvariouschannels,suchasOracleTechnologyNetworkforums,developercommunities,andblogs.UsersareencouragedtoparticipateintheOracleSQLDeveloperExchangeprogram(https://sqldeveloper.oracle.com),whereyoucanregisterafeaturerequestandsubmitcodesnippetsortooltips.

https://sqldeveloper.oracle.com

HistoryandbackgroundThefirstreleaseofSQLDeveloperwasmadeinMarch2006.Theinitialreleaseincludedthebasicfunctionalities,suchasexecutingSQLqueriesandPL/SQLblocks,andinvokingSQL*Plusscripts.Thereafter,therewereafewquickpatchesandanimportantreleaseofSQLDeveloper1.1wasmadeinDecember2006.Sincethen,thetoolhasevolvedwithabroadspectrumoffeaturesandsupportfordatabaseoptions.

Let’stakeaquickglanceattheearlierreleasesoftheSQLDevelopertool:

SQLDeveloperreleaseversion

Releasedate Keynewfeatures

SQLDeveloper1.0 March2006 InitialreleaseenabledtheexecutionofSQLandPL/SQLstatements

SQLDeveloper1.1 December2006

File-basedPL/SQLediting.PatchesSQLDeveloper1.1.1(Jan2007),SQLDeveloper1.1.2(March2007),andSQLDeveloper1.1.3(May2007)

SQLDeveloper1.2 June2007 DevelopermigrationworkbenchSupportforOracleApplicationExpress3.0.1

SQLDeveloper1.5 April2008 Supportforversioncontrol


Third-partydatabasemigrationsupportPL/SQLunittestingIntegrateddatamodelerviewer

SQLDeveloper2.1.1 March2010 Patchrelease

SQLDeveloper3.0 March2011

QuerybuilderDBAnavigatorSchedulebuilder

SQLDeveloper3.1 February2012

SupportforRecoveryManager(RMAN)SupportforDataPumpPDFreporting

SQLDeveloper3.2 November2012

SupportformanagingtheAPEXlistenerImprovedDatabaseDiffandDBDOCfeatures


SupportforOracleDatabase12cMultitenantandDatabaseasaServiceplatformStablereleasewithupdatedframework

SQLDeveloper4.1 May2015OptimalmemoryfootprintRequirementforJava7JDKSupportsubversion1.7

SQLDeveloperforDevelopersSQLDeveloperprovidesapowerfuleditorforrunningandanalyzingSQLqueriesanddevelopingPL/SQLprograms.Asadatabasedeveloper,youcanbrowseschemaobjects,viewobjectattributes,andcompilestoredsubprograms.YoucanrunaSQLquery(orinvokeascript),retrievetheresult,exportitintoanXML,XLS,orPDF,andexaminethequeryexplainplan.Youcancreate,edit,debug,compile,ordropstoredPL/SQLsubprograms.

SQLDeveloperforDatabaseAdministratorsInitsinitialdays,SQLDeveloperwasadeveloper-centrictool.However,thelaterreleasesofthetoolbroadeneditsadministrativeofferings.Databaseadministratorscanperformtheirroutinedatabaseactivitiesincludingstoragemanagement,backupandrecoveryoperations,dataexportandimport,databaseauditing,diagnosticspackfeatures,anddatabaseresourcemanagement.

ThelatestversionofSQLDevelopersupportspluggabledatabaseoperationsinamultitenantcontainerdatabase.Youcancreate,drop,unplug,plug,orclone,apluggabledatabase.

TheManageDatabaseoptionintheconnectiontreeallowsauserwithSYSDBAprivilegetoreporttheusageofdatabasetablespaces.Besides,thereareavarietyofpre-definedDatabaseAdministrationreports,whichfurnishagreatdealofinformationfromadatabase-managementstandpoint.AnewdedicatedDBApanelisavailablefordatabaseadministrationactivities.ExistingDBAconnectionscanbecopiedfromtheconnectiontreetotheDBApanelandcanbeusedtomanagetheOracleDatabase.

Notonlyfordevelopersandadministrators,SQLDevelopersuccessfullyconnectsthearchitectcommunityaswell.DatabasearchitectscanperformdatamodelingwiththeSDDM(SQLDeveloperDataModeler)module,integratedwithSQLDeveloper.

SQLcl–ThenewSQLcommandlineSQLclisthemodernizedandrebrandedversionofthegoodoldSQL*Plus.SQL*Plushasbeentheprimarycommand-lineinterfaceforSQLexecutionformanyyears.

OracleSQLDeveloper,asweareallaware,providesmultiple-userinterfacefeaturesforapplicationdeveloperstoformatandeditSQLtext,exportqueryresultindesiredfileformats,objectnamecompletion,maintainsSQLhistory,anddoesmuchmore.SQLcl,beingacommand-lineinterfaceutility,inheritsthedeveloper-friendlyformattingandeditingelementsofSQLworksheetfromtheSQLDeveloper.WithSQLcl,thedeveloperanduserexperienceswillbeimprovedbyanorderofmagnitude.

NoteYoucandownloadtheSQLcl-EarlyAdopterbinariesfromthedownloadspageofSQLDeveloper(http://www.oracle.com/technetwork/developer-tools/sql-developer/downloads/index.html).

Currently,theutilityisavailableforstandalonedownload,butinfutureitwillbepartoftheSQLDeveloper4.1andOracleDatabase12cRelease2softwarepackages.Forinstallation,youmusthaveJavaRuntimeEnvironment(JRE)1.7orhigheronyoursystem.

NoteFortheSQLcloverview,watchtheYouTubevideoathttps://www.youtube.com/watch?v=HApdy-o525A.

Let’sbrieflydiscusssomeofthekeyfeaturesandcommandsofSQLcl:

Databaseconnection:SQLclsupportsdatabaseconnectionthroughEZConnect,TNSfromtheOracleclientortheTNS_ADMINenvironmentvariable,andLDAP.YoucanstorethedatabaseconnectionsusingtheNETcommand.Object-name/Commandcompletion:PressingtheTabkeywhileyoutypeanobjectnamewillauto-completetheobjectnameinuppercase.Multilineedits:InsteadofusinganeditortomakechangestotheSQLquery,SQLclallowsyoutoworkwiththekeyboardkeys(Enter,Backspace,forwardandbackward)toedittheSQLquery.ALIAS:SQLclenablesyoutocreateanaliasforanSQLqueryoraPL/SQLblock.Toinvokethealias,simplytypethealiasnameintheSQLclprompt.CD:SimilarlytotheOScommand,youcanchangethedirectoryfromtheSQLclinterfacebyusingtheCDcommand.ThiscommandwillpreventSQLdevelopersfromincludingOSpathsinthescripts.CTAS:ThisacronymcanbeuseddirectlyinplaceofCREATETABLEASSELECTtogenerateaDDLscriptofanewtablefromanexistingone.YoucantransformthecommandoutputbysettingthetransformationparametersusingtheDBMS_METADATApackage.DDL:ThiscommandgeneratestheDDLscriptforagivenobject(itoptionallywritestheoutputtoafiletoo).

http://www.oracle.com/technetwork/developer-tools/sql-developer/downloads/index.html

https://www.youtube.com/watch?v=HApdy-o525A

SQLFORMAT:Youcanapplydifferentformatstothequeryresults.Itmaybeapplyingadifferentcolorinansiconsole,JSON,XML,CSV,HTML,insert,loader,delimited,ortext.SQLhistory:SQLclstoresthelast100commandsexecutedbyallthedatabaseusers.INFORMATION:ThenewSQLclcommandisanadvancedversionoftheDESCRIBEcommand.Besideslistingtheobjectstructureoraprogramsignature,theINFOandINFO+commandsprovidemoredetailedinformation.

GettingstartedwithSQLDeveloperTostartworkingwiththeSQLDevelopertool,youmustfollowthefollowingsteps:

1. DownloadthelatestbinariesoftheSQLDevelopertoolfromtheOracleTechnologyNetwork.

NoteGotohttp://www.oracle.com/technology/products/database/sql_developerforthemostrecentstandaloneversionofthetool.Thistoolcanbedownloadedforfree.

2. Alternatively,youmayalsofindthesoftwarebinariesshippedalongwiththeOracleDatabaseorOracleJDevelopersoftwaremedia.

3. EnsurethattheJavaDevelopmentKit(JDK)isinstalledonthetargetsystem.Usually,theSQLDeveloperproductdoesn’tincludetheJDKexceptonMicrosoftWindows.OnWindows,aversionofproductbinariesalsoincludestheJDK.Afterstartup,thecorrectJDKpathmustbespecifiedforSQLDeveloper.

4. RunthesqldeveloperexecutablefromtheunzippedSQLDeveloperfolder.SpecifythefullpathoftheJDK:

TheSQLDeveloperhomepageincludesmultipletutorialstohelpyougetstarted,anditassistsyouwiththekeyfunctionalitiesofthetool:

http://www.oracle.com/technology/products/database/sql_developer

CreatingadatabaseconnectionIfyouknowthelogincredentialsofadatabaseuser,youcansavetheconnectiondetailswithinSQLDeveloper.Thelogincredentialsincludetheusername,password,serverIPaddress,anddatabaseSID.ThefollowingimageshowshowtocreateadatabaseconnectioninSQLDeveloper:

Thestepsforcreatingadatabaseconnectionareasfollows:

1. ProvideaConnectionName,databaseUsername,andPassword.2. Providetheconnectiontype,role(default/SYSDBA),anddatabaseserverdetailssuch

asthemachinenameorIPaddress,Port,anddatabaseSID.3. ClickonTesttoverifytheconnectiondetails.Status:Successwillconfirmthe

connectionproperties.4. ClickonSavetostoretheconnectionpropertiesforfutureuse.5. ClickonConnecttoconnecttothedatabaseusingthecurrentconnectiondetails.

UsingtheSQLworksheetAfterestablishingtheconnectiontothedatabase,SQLDeveloperopensupanSQLworksheettoexecuteSQLqueriesandPL/SQLprograms.

Forexample,thefollowingscreenshotfromSQLDevelopershowsaSELECTqueryontheEMPtableandthequeryoutputinthefollowinggrid.NotetheschemabrowserandtheDBApanelintheleftpaneofthetool:

SQLWorksheetintheSQLDeveloper

EachoftheSQLworksheetscomprisemultipleicons,asshowninthefollowingfigure:

Thefunctionofeachicon,goingfromlefttoright,isdescribedasfollows:

RunStatement:SelectanSQLquerytextorPL/SQLblockandclickonthisto

executeitRunScript:executeastoredscriptExplainPlan:generatetheexplainplanofanSQLAutotrace:examinetheautotraceparametersSQLTuningAdvisor:analyzesimpleorcomplexSQLstatementsandprovidetuningrecommendationsCommit:COMMITanactivetransactionRollback:ROLLBACKatransactionOpenaSQLWorksheet:openanonsharedSQLworksheetToUpper/Lower/Initcap:changethecaseofthequeryidentifiersClear:clearthecontentoftheSQLworksheetSQLHistory:listtheSQLstatementspreviouslyexecutedTimesTenIndexAdvisor:analyzetheSQLworkloadandrecommendindexes

Theresultinggridatthebottomprovidesiconsforpinningaqueryresult,printingoutput,refreshingtheresult,anddisplayingtheSQLstatement.Attheresultsetlevel,itincludesthefollowingfunctionalities:

SaveGridasReport:ThisallowstheusertosaveanSQLqueryasareport.SingleRecordView:Thisprovidesasinglerecordviewinadialogbox.CountRows:Thisreturnsthecountofrowsinthequeryresultset.Find/Highlight:Thissearchesfortextandhighlightsitsoccurrences.PublishtoAPEX:ThisallowsquickcreationofanAPEXapplicationpagefromtheSQLquery.Itrequiresdetailssuchastheworkspace,applicationname,theme,pagename,andunderlyingSQL.Export:Thisexportsthequeryresultsetasinsertscripts,SQL*Loader,CSV,delimited,HTML,XLS,PDF,orXML.

CorefeaturesofSQLDeveloperThecorefunctionalitiesofSQLDeveloperarethosethathelpdevelopersandadministratorstodrivetheirday-to-dayactivitieswitheaseandenhancedproductivity.

ObjectBrowserYoucanbrowsetheobjectsinauserschemabyexpandingasavedconnection(whichrepresentsaschema).Youcanfindtables,(editioning)views,indexes,packages,procedures,functions,(crossedition)triggers,types,sequences,materializedviews,materializedviewlogs,(public)synonyms,(public)databaselinks,editions,directories,andotherschemaobjects.

PL/SQLEditorandDebuggerTheprocedureeditorallowsyoutocreateoreditaPL/SQLpackage,storedprocedure,orstoredfunction.Youcancompile/compilefordebug,debug,orprofiletheprogramunitsfromtheeditor.

Thefollowingscreenshotshowsaprocedure,P_CALC_POINT_CALLSTACK,intheprocedureeditor.NotetheErrors,Grants,Profiles,References,Details,andDependenciestabs.Thetoolbariconsallowtheusertorun,debug,compile,setread-onlymode,andprofiletheprogramunit:

DBAPanelYoucaneitheraddexistingconnectionsfromtheconnectiontreeorcreateanewconnectionwithSYSDBAprivileges.UndertheDBApanel,youcanperformthecorefunctionsofadatabaseadministratorliketheoneshowninthefollowingfigure:

NoteUseofPerformanceunderDBAConsolerequiresOracleDiagnosticsPack.ItisincludedinSQLDeveloper4.0.

DatabaseUtilitiesThissectionbrieflydescribesthedatabaseutilitiesavailableinSQLDeveloper:

DatabaseCopy:Thisallowsthecopyingofdatafromoneconnectiontoanotherconnection.Copyoptionscanbeobjectcopy,schemacopyortablespacecopy.DatabaseDiff:Thisutilitycomparestwoconnectionsonallorselectedtypesofobject,andgeneratesthedeltareport.DatabaseExport:Thisisusedtogeneratethecreation(DDL),aswellasdatainsertscripts,forallselectedobjecttypes.Migration:Thisisusedtomigrateathird-partydatabasetoOracle.Thenon-Oracle

databasesthatcanbetranslatedtoOraclecanbeMySQL,MicrosoftSQLServer,Sybase,andIBMDB2.SQLDeveloperallowsyoutocreateadatabaseconnectiontothenon-Oracledatabases.Themigrationprocessinvolvesthecreationofamigrationprojectandamigrationrepositorytoholdthemetainformationofthenon-Oracleobjects.Thetranslationframeworkisthenusedtotranslateallnon-OracleobjectstoOracle-specificcodeandgeneratetheDDLscripts.AftertheDDLscriptsareexecuted,thelaststepoftheprocessisdatamigration.SQLMonitor:Thisenablesreal-timeSQLmonitoringforaconnection.ThefeaturerequirestheOracleTuningPack.

TheDataModelerTheDataModelerisafreedatabasedesignandmodelingtoolintegratedwithSQLDeveloper.SQLDeveloperprovidesagraphicaluserinterfacetocreateandmanagedatamodels.TheuniquecapabilitiesoftheDataModelersimplifymodelingtasksandhelpsdesignerstoachievebetterproductivity.AlthoughitisintegratedwithSQLDeveloperasanextension,thetoolisavailableforstandalonedownloadaswell.

Thistoolallowsyoutostrategizeandanalyzelogicaldatamodels.Italsoallowsyoutodrawrelationalandphysicaldatamodels.YoucanalsoimporttheERDsandsharethemwithyourpeersforreviewdiscussions,futurereference,re-engineeringormanagementapproval.

SQLDeveloperreportsOracleSQLDeveloperstoresmultiplepredefinedreports,whichrunbasedonuser-providedinputs.Theusermustsupplythevaluesforthebindvariablesrequiredforthereportexecution.Someofthepopularreportsareobjectreports,PL/SQLreports,andDBAreports.Objectreportscanbeusedtogeneratedependencytrackingandinvalidobjects.PL/SQLreportscanbeusedtoreporttheargumentusageinagivenprogramunitorcompleteschema.DatabaseadministrationreportscanbeusedtogeneratereportsonSQLcursors,databaseparameters,locks,memoryconsumption,session-wiseinformation,topSQLreports,andwaitsandevents.Otherreports,suchastheAWRandASHreports,revealactivesessionhistorystatisticsandthelastAWRgenerated.

Notethatthesereportsaredifferentfromtheuser-definedreports.TheOracle-definedreportsarenon-editable,buttheycanbeincludedintheuser-definedreportsaschildreportsormultilevelreports:

VersioncontrolSQLDeveloperincludessupportforversioncontrol,whichhelpsinmaintainingthesourcecodeversions.Youcanimplementsourcecontrolbyimportingthefilestobeversioned,check-outwhenrequired,andcheck-inafterthechangeshavebeencommitted.

TheSQLTranslationFrameworkTheSQLTranslationFrameworkisusedtotranslateSQLstatementsfromanon-OracleDatabasescripttoanOracleDatabaseSQLscript.ItisinstalledalongwiththeOracleDatabasesoftware.However,itmustbeconfiguredwiththeappropriateSQLTranslatortoidentifythenon-OraclecodeandconvertitintoOracle-compliantcode.Duringthetranslationprocess,aprofile(knownastheSQLTranslationProfile)isgeneratedfortheSQLTranslatortoreviewandeditthetranslations.ASQLTranslatormayhavemultipleSQLTranslationProfiles.

SQLDeveloper4.0and4.1NewFeaturesThelatestversion,SQLDeveloper4.1,introducesnumerousenhancementsandfeatures.Thefollowingisalistofnewfeatures:

SupportforJDK8:SQLDeveloper4.1runsonJDK8.Databaseperformancemonitoring:SQLDeveloper4.0includedanodeundertheDBAconnectiontreeforOracleDiagnosticsPack.Theperformanceengineerscannowcapturesnapshots,establishbaselines,runASHandAWR,anddisplayAutomaticDatabaseDiagnosticMonitor(ADDM)reports.FullsupportforOracleDatabase12cfeatures:SQLDeveloper4.0fullysupportstheOracleDatabase12cfeatures.Inamultitenantdatabase,acontainerdatabaseadministratorcancomfortablyworkwithSQLDevelopertomanagepluggabledatabases.Youcancreate,clone,drop,plug,orunplugapluggabledatabase.Similarly,youcancreateandmanagedataredactionpoliciesonthetables.YoucanalsocloneapluggabledatabasedirectlytotheOraclecloud.

OtherlanguageenhancementsinOracleDatabase12c,suchastheIDENTITYcolumns,FETCHFIRST,32KVARCHAR2support,implicitcursors,anddefaulttoasequencegenerator,enableefficientmigrationfromnon-OracletoOracle.

SupportforOracleDatabaseproducts:SQLDeveloper4.0supportsDataMining,TimesTen,XMLDB,andSpatialandgraphs.InstanceViewer:Withouttheneedforanagentinstallationontheserver,SQLDevelopercandisplayyourdatabaseinstancestatusandcurrentactivity.Theinstanceactivityislocallycachedandgraphicallydrawn,andgetsrefreshedfromtimetotime.FromtheDBAPanelconnectiontree,selectDatabaseStatusnodeandclickonDBInstance.Objectsearch:Theenhancedobjectsearchallowsanobjecttobesearchedacrossschemasandobjecttypesandthroughtheidentifiersandtheirappearances.Thehistoryofsearchedobjects,alongwiththechoices,issavedforfutureaccess:

Newsearchandreplace:Thesearchtextfieldintheprocedureeditorisenhancedtohighlighttheoccurrencesofsearchedtext,savethehistoryoftextssearched,andtoallowreplacementofexistingtextwithreplacementtext.Inaddition,multicursoreditingenableseasyformattingofmultiplerowsinanSQLworksheet.PDBcloningtoOracleDatabaseCloudService:SQLDeveloper4.1allowsaPDBtobecloneddirectlytotheOracleDatabaseCloud.AcloudconnectionmustbecreatedwiththeDatabaseCloudServiceenvironmentdetails.SupportforOracleNoSQLDatabase:SQLDeveloper4.1supportsOracleNoSQLKVLitestores.Importdatafromaspreadsheet:SQLDeveloper4.1allowsthedatafromaspreadsheettobedirectlyimportedintoatable.Thespreadsheetdatacanbeimportedtoanexistingtableoranewtable.

SummarySQLDeveloperhasmaturedimmenselyovertheyearsandhasemergedastheprimaryIDEforOracleDatabase.FullsupportforOracleDatabaseoptionsintraditionalaswellasclouddeploymentsandthemostrecentdatabasefeaturesarethekeydifferentiatorsofthetool.Thistoolisnotonlymeantforapplicationdevelopers,butalsoprovideswidesupportfordatabaseadministratorsandarchitects.SQLclisgainingalotoftractioninthedevelopercommunitybecauseofitsadvancedformattingandeditingfeatures.

IndexA

ActiveSessionHistory(ASH)/In-MemoryAdvisorAmericanNationalStandardInstitute(ANSI)/IDENTITYcolumnsarchivelogs/DatabaseconsolidationandthenewMultitenantarchitectureassociativeaarays

about/Collectiontypesassociativearrays

about/Associativearraysfeatures/Associativearrays

AutomaticDatabaseDiagnosticMonitor(ADDM)about/SQLDeveloper4.0and4.1NewFeatures

AutomaticSegmentSpaceManagement(ASSM)/DeduplicationandcompressionAutomaticWorkloadRepository(AWR)/In-MemoryAdvisor

BBasicFiles

migrating,toSecureFiles/MigratingBasicFilestoSecureFilesBFILE/BFILEbinaries,SQLDeveloper

URL,fordownloading/GettingstartedwithSQLDeveloperBinaryLargeObject(BLOB)/BLOBandCLOBBufferCache

versusResultCache/ResultCacheversusBufferCachebulkbinding/FORALLBULKCOLLECT/BULKCOLLECTbulkprocessing,inPL/SQL

about/BulkprocessinginPL/SQLBULKCOLLECT/BULKCOLLECTFORALL/FORALLFORALLandexceptionhandling/FORALLandexceptionhandling

CCharacterLargeObject(CLOB)/BLOBandCLOBcollection

overview/Introductiontocollectionsnon-persistentcollection/Introductiontocollectionspersistentcollection/Introductiontocollectionstypes/Collectiontypesassociativearray/Collectiontypesnestedtable/Collectiontypesvarray/Collectiontypes

collectionmethods,PL/SQLabout/PL/SQLcollectionmethodsEXISTSfunction/EXISTSCOUNTfunction/COUNTLIMITfunction/LIMITFIRSTfunction/FIRSTandLASTLastfunction/FIRSTandLASTPRIORfunction/PRIORandNEXTNEXTfunction/PRIORandNEXTEXTENDfunction/EXTENDTRIMfunction/TRIMDELETEfunction/DELETE

collectiontypescomparing/Comparingthecollectiontypesselecting/Selectingtheappropriatecollectiontype

compilationmodeselecting/Selectingtheappropriatecompilationmodesetting/Settingthecompilationmodesettings,querying/Queryingthecompilationsettings

COUNTfunction/COUNTcursorattributes

%ROWCOUNT/Cursorattributes,Cursorattributes%ISOPEN/Cursorattributes,Cursorattributes%FOUND/Cursorattributes,Cursorattributes%NOTFOUND/Cursorattributes,Cursorattributesabout/Cursorattributes

cursorexecutioncycleabout/Cursorexecutioncycle

cursorexecutioncycle,stagesOPEN/CursorexecutioncyclePARSE/CursorexecutioncycleBIND/CursorexecutioncycleEXECUTE/Cursorexecutioncycle

FETCH/CursorexecutioncycleCLOSE/Cursorexecutioncycle

cursorsabout/Cursors–anoverviewexecutioncycle/Thecursorexecutioncyclecursorattributes/CursorattributesCursorFORloop/CursorFORloop

cursorstructuresabout/Cursorstructuresimplicitcursors/Cursorstructures,Implicitcursorsexplicitcursors/Cursorstructures,Explicitcursorscursorexecutioncycle/Cursorexecutioncycle

cursorvariablesabout/Cursorvariablesweakrefcursor,types/Strongandweakrefcursortypesstrongrefcursor,types/Strongandweakrefcursortypesworkingwith/WorkingwithcursorvariablesSYS_REFCURSOR/SYS_REFCURSORasarguments/Cursorvariablesasargumentsrestrictions/Cursorvariables–restrictionscursordesign,considerations/Cursordesignconsiderationscursordesign,guidelines/Cursordesign–guidelines

Ddatabaseconnection

creating/Creatingadatabaseconnectiondatabaseconsolidation

about/DatabaseconsolidationandthenewMultitenantarchitecturedatabasedependency

managing/Managingdatabasedependenciesdirect/Managingdatabasedependenciesindirect/Managingdatabasedependenciesdirectdependency,displaying/Displayingthedirectandindirectdependenciesindirectdependency,displaying/Displayingthedirectandindirectdependenciesmetadata/Dependencymetadataissues/Dependencyissuesandenhancementsenhancement/Dependencyissuesandenhancements

DatabaseIn-MemoryversusResultCache/ResultCacheversusOracle12cDatabaseIn-Memory

databaseresourcemanager(DBRM)/CDBResourceManagementDatabaseUtilitiesoption

DatabaseCopy/DatabaseUtilitiesDatabaseDiff/DatabaseUtilitiesDatabaseExport/DatabaseUtilitiesMigration/DatabaseUtilitiesSQLMonitor/DatabaseUtilities

DataModelerabout/TheDataModeler

DBMS_ASSERTsubprogramused,forsanitizinginputs/SanitizinginputsusingDBMS_ASSERTunquotedidentifier/Unquotedidentifiersquotedidentifier/Quotedidentifiersliteral/Literalslimitations/DBMS_ASSERT–limitations

DBMS_HPROFpackageabout/TheDBMS_HPROFpackageandDBMS_PROFILER,differences/DifferencesbetweenDBMS_PROFILERandDBMS_HPROFsubprograms/DBMS_HPROFsubprogramsDataCollector/DBMS_HPROFsubprogramsAnalyzer/DBMS_HPROFsubprograms

DBMS_LOBpackageabout/TheDBMS_LOBpackageDBMS_LOBconstants/TheDBMS_LOBconstantsDBMS_LOBdatatypes/TheDBMS_LOBdatatypes

DBMS_LOBsubprograms/TheDBMS_LOBsubprogramsDBMS_METADATApackage

about/TheDBMS_METADATApackagedatatypes/DBMS_METADATAdatatypesandsubprogramsURL/DBMS_METADATAdatatypesandsubprogramssubprograms/DBMS_METADATAdatatypesandsubprogramstransformationparameters/TheDBMS_METADATAtransformationparametersandfiltersfilters/TheDBMS_METADATAtransformationparametersandfiltersdemonstration/Demonstration

DBMS_RESULT_CACHEpackageabout/TheDBMS_RESULT_CACHEpackageresultcachememoryreport,displaying/DisplayingtheresultcachememoryreportOracleDatabase12cenhancements,toPL/SQLfunctioncache/OracleDatabase12cenhancementstothePL/SQLfunctionResultCache

DBMS_TRACEpackageinstalling/InstallingtheDBMS_TRACEpackagesubprograms/DBMS_TRACEsubprograms

DBMS_TRACEsubprogramsURL/DBMS_TRACEsubprograms

deadcodeabout/Case2:WhenPLSQL_OPTIMIZE_LEVEL=1

DEFAULTONNULLclause/TheDEFAULTONNULLclausedensecollection/Nestedtablesdynamiclinkedlibrary(DLL)/ExternalProcedures,Nativeandinterpretedcompilationtechniques

EEarlyAdopterbinaries,SQLcl

URL/SQLcl–ThenewSQLcommandlineenvironmentsetup,externalprocedures

TNSNAMES.ora/TNSNAMES.oraEXTPROC.ora/EXTPROC.ora

exceptionhandlingabout/ExceptionhandlinginPL/SQLsystem-definedexceptions/System-definedexceptionsuser-definedexceptions/User-definedexceptionsexceptionpropagation/Exceptionpropagation

EXISTSfunction/EXISTSexplicitcursors/Cursors–anoverview,Cursorstructures

about/ExplicitcursorsEXTENDfunction/EXTENDexternalCprograms

executing,fromPL/SQL/ExecutingexternalCprogramsfromPL/SQLexternalLOB/ExternalLOBexternalprocedures

about/OverviewofExternalProcedures,ExternalProceduresexecutionflow,components/Componentsofexternalprocedureexecutionflowextprocagent/Theextprocagentlibraryobject/TheLibraryobjectcallout/CalloutandCallbackcallback/CalloutandCallbackcallspecification/CallSpecificationexecuting/HowanExternalProcedureexecutesenvironmentsetup/Environmentsetupsecuring,withOracledatabase12c/SecuringExternalProcedureswithOracleDatabase12c

extprocagent,externalprocedures/Theextprocagent

Ffeatures,SQLDeveloper

about/CorefeaturesofSQLDeveloperObjectBrowser/ObjectBrowserPL/SQLEditorandDebugger/PL/SQLEditorandDebuggerDataModeler/TheDataModelerSQLDeveloperreports/SQLDeveloperreportsversioncontrol/VersioncontrolSQLTranslationFramework/TheSQLTranslationFramework

FETCHFIRSTclause/RowlimitingusingFETCHFIRSTFine-grainedaccesscontrol(FGAC)

about/Fine-GrainedAccessControlworking/HowFGACworks

FineGrainedDependency(FGD)/DependencyissuesandenhancementsFIRSTfunction/FIRSTandLASTFORALL/FORALL

andexceptionhandling/FORALLandexceptionhandlingfunctionalities,SQLworksheet

SaveGridasReport/UsingtheSQLworksheetSingleRecordView/UsingtheSQLworksheetCountRows/UsingtheSQLworksheetFind/Highlight/UsingtheSQLworksheetPublishtoAPEX/UsingtheSQLworksheetExport/UsingtheSQLworksheet

functionsabout/Functionsfeatures/Functionsexecutionmethods/Functions–executionmethodscallingfromSQLexpressions,restrictions/RestrictionsoncallingfunctionsfromSQLexpressions

Iicons,SQLworksheet

RunStatement/UsingtheSQLworksheetidentifiertypes

determining/DeterminingidentifiertypesandusagesUSER_IDENTIFIERSview/USER_IDENTIFIERSPL/Scopetool/ThePL/ScopetoolPLSCOPE_SETTINGSparameter/ThePLSCOPE_SETTINGSparameter

implicitcursors/Cursors–anoverviewabout/Cursorstructures,Implicitcursors

implicitdatatypeconversionavoiding/Avoidinganimplicitdatatypeconversion

In-DatabaseArchiving/In-DatabaseArchivingIn-MemoryDatabaseCache(IMDB)

versusResultCache/ResultCacheversusIn-MemoryDatabaseCacheindex-organizedtable(IOT)/Nestedtableinanindex-organizedtableinjection/WhatisSQLinjection?interpretedcompilation

programunit,comparing/Compilingaprogramunitfornativeorinterpretedcompilation

IPC(InternetProcedureCalls)/TNSNAMES.ora

JJavaDevelopmentKit(JDK)/GettingstartedwithSQLDeveloperJavaprograms,executingfromPL/SQL

about/ExecutingJavaprogramsfromPL/SQLJavaclass,loadingintodatabase/LoadingaJavaclassintoadatabaseJavaclass,executingfromOraclePL/SQLunit/StepstoexecuteaJavaclassfromanOraclePL/SQLunit

JavaRuntimeEnvironment(JRE)/SQLcl–ThenewSQLcommandline

K32KVARCHAR2/Supportfor32KVARCHAR2keyfeaturesandcommands,SQLcl

databaseconnection/SQLcl–ThenewSQLcommandlineObject-name/Commandcompletion/SQLcl–ThenewSQLcommandlinemultilineedits/SQLcl–ThenewSQLcommandlineCD/SQLcl–ThenewSQLcommandlineCTAS/SQLcl–ThenewSQLcommandlineDDL/SQLcl–ThenewSQLcommandlineSQLFORMAT/SQLcl–ThenewSQLcommandlineSQLhistory/SQLcl–ThenewSQLcommandlineINFORMATION/SQLcl–ThenewSQLcommandline

LLASTfunction/FIRSTandLASTlibraryobject,externalprocedures/TheLibraryobjectLibunits/ExecutingJavaprogramsfromPL/SQLLIMITfunction/LIMITLOBs

about/IntroductiontoLargeObjectssecurity/IntroductiontoLargeObjectsdatatypes,classifying/ClassificationofLargeObjectdatatypesinternalLOB/InternalLOBtemporaryLOB/PersistentandTemporaryLOBpermanentLOB/PersistentandTemporaryLOBexternalLOB/ExternalLOBrestrictions/LOBrestrictionslocator/TheLOBlocatorinstanceinitialization/LOBinstanceinitializationDBMS_LOBpackage/TheDBMS_LOBpackageusagenotes/LOBusagenotesworkingwith/WorkingwithLOBsmetadata/LOBmetadataSecureFileadvancedfeatures,securing/EnablingtheadvancedfeaturesofaSecureFiledata,populating/PopulatingtheLOBdatatemporaryLOBoperations/TemporaryLOBoperations,ManagingtemporaryLOBsLONG,migratingto/MigratingLONGtoLOBs

LOBs,datatypesabout/LOBdatatypesinOracleBinaryLargeObject(BLOB)/BLOBandCLOBCharacterLargeObject(CLOB)/BLOBandCLOBNCLOB/BLOBandCLOBBFILE/BFILE

localuser/CommonusersandlocalusersLONG,migratingtoLOBs

ALTERTABLEcommand,using/UsetheALTERTABLEcommandTO_LOBfunction,using/UsingtheTO_LOBfunctionOnlineTableRedefinition/OnlineTableRedefinition

LRU(LeastRecentlyUsed)/WhatistheServerResultCache?

Mmachinecode(M-code)

about/ThePL/SQLCompiler

Nnativecompilation

about/Nativeandinterpretedcompilationtechniquesprogramunit,comparing/Compilingaprogramunitfornativeorinterpretedcompilation

nestedtableabout/Collectiontypes,Nestedtablesobjecttype,modifying/Modifyanddropanestedtableobjecttypeobjecttype,dropping/Modifyanddropanestedtableobjecttypedesignconsiderations/Designconsiderationsofanestedtablestorage/Nestedtablestorageinindexorganizedtable/Nestedtableinanindex-organizedtablelocators/Nestedtablelocatorsasschemaobject/Nestedtableastheschemaobjecttypecolumn,operations/Operationsonanestedtabletypecolumninstance,creating/Createanestedtableinstancecolumn,querying/Queryinganestedtablecolumncollectiontype,inPL/SQL/NestedtablecollectiontypeinPL/SQLcollection,initialization/Collectioninitializationmetadata,querying/Queryingthenestedtablemetadata

NEXTfunction/PRIORandNEXTNOTNULLconstraint

about/UnderstandingtheNOTNULLconstraint

OObjectBrowser

about/ObjectBrowserOCI(OracleCallInterface)/OCIClientresultscacheOCIClientresultscache

about/OCIClientresultscacheparameters/OCIClientresultscache

Oracle-suppliedpackagesreviewing/ReviewingOracle-suppliedpackagesDBMS_ALERT/ReviewingOracle-suppliedpackagesDBMS_LOCK/ReviewingOracle-suppliedpackagesDBMS_SESSION/ReviewingOracle-suppliedpackagesDBMS_OUTPUT/ReviewingOracle-suppliedpackagesDBMS_HTTP/ReviewingOracle-suppliedpackagesUTL_FILE/ReviewingOracle-suppliedpackagesUTL_MAIL/ReviewingOracle-suppliedpackagesDBMS_SCHEDULER/ReviewingOracle-suppliedpackagesDBMS_PARALLEL_EXECUTE/ReviewingOracle-suppliedpackagesDBMS_PRIVILEGE_CAPTURE/ReviewingOracle-suppliedpackagesDBMS_REDACT/ReviewingOracle-suppliedpackagesDBMS_RESOURCE_MANAGER/ReviewingOracle-suppliedpackagesDBMS_DATAPUMP/ReviewingOracle-suppliedpackagesDBMS_PDB/ReviewingOracle-suppliedpackagesDBMS_SQL/ReviewingOracle-suppliedpackagesDBMS_REDEFINITON/ReviewingOracle-suppliedpackagesDBMS_UTILITY/ReviewingOracle-suppliedpackagescategorizing/ReviewingOracle-suppliedpackages

Oracle11g/MultitenantforConsolidationOracle12ccontainerdatabase(CDB)

about/DatabaseconsolidationandthenewMultitenantarchitectureOracle12cSQLandPL/SQL,features

about/Oracle12cSQLandPL/SQLnewfeaturesIDENTITYcolumns/IDENTITYcolumnscolumnvalue,tosequenceinOracle12c/DefaultcolumnvaluetoasequenceinOracle12cDEFAULTONNULLclause/TheDEFAULTONNULLclause32KVARCHAR2,supportfor/Supportfor32KVARCHAR2Rowlimiting,FETCHFIRSTused/RowlimitingusingFETCHFIRSTinvisiblecolumns/Invisiblecolumnstemporaldatabases/TemporaldatabasesIn-DatabaseArchiving/In-DatabaseArchiving

OracleAdvancedSecurity/OracleDatabaseSecurityoverviewOracleAuditVaultandDatabaseFirewall(AVDF)

about/OracleDatabaseSecurityoverviewOracledatabase11gRealnativecompilation

about/OracleDatabase11gRealNativeCompilationOracleDatabase11gresultcache

about/OracleDatabase11gResultCacheServerResultCache/WhatistheServerResultCache?ServerResultCache,configuring/ConfiguringtheServerResultCacheResultCache,versusBufferCache/ResultCacheversusBufferCacheResultCache,versusDatabaseIn-Memory/ResultCacheversusOracle12cDatabaseIn-MemoryResultCache,versusIn-MemoryDatabaseCache(IMDB)/ResultCacheversusIn-MemoryDatabaseCache

OracleDatabase12cimplicitstatementresults/ImplicitstatementresultsinOracleDatabase12cenhancements,tocollections/Oracle12cenhancementstocollections

Oracledatabase12cexternalprocedures,securingwith/SecuringExternalProcedureswithOracleDatabase12c

OracleDatabase12c(12.1.0.2),In-Memoryoptionabout/TheOracleDatabase12c(12.1.0.2)In-Memoryoptionchallenge/Thechallengeandproblemstatement/TheproblemstatementandOracleDatabase12cIn-Memoryfeatures/OracleDatabase12cIn-Memoryoptionfeaturesarchitecture/TheOracleDatabase12cIn-MemoryArchitecturestore,controlling/ControllingtheIn-MemorycolumnstoreINMEMORYclause/TheINMEMORYclauseperformanceoptimizations/PerformanceoptimizationsIn-MemoryAdvisor/In-MemoryAdvisorOracleDatabaseIn-Memorybenefits/OracleDatabaseIn-Memorybenefits

Oracledatabase12cDataRedactionabout/OracleDatabase12cDataRedactionfeatures/DataRedactionexemptionsandmiscellaneousfeaturesfunctiontypes/DataRedactionfunctiontypesdemonstration/Demonstrationmetadata/TheDataRedactionmetadata

OracleDatabase12cenhancementstoPL/SQLsubprograms/OracleDatabase12cenhancementstoPL/SQLsubprograms

OracleDatabase12cmultitenantarchitecture,featuresabout/TheOracleDatabase12cMultitenantarchitecture–featuresmultitenantforconsolidation/MultitenantforConsolidationplug/unplug/Plug/unplugmanagemanyasone/ManageManyasOne

rapidprovisioning/RapidprovisioningCDBresourcemanagement/CDBResourceManagementcommonusers/Commonusersandlocalusers

Oracledatabase12csecurity,enhancementsabout/OracleDatabase12cSecurityenhancements,OracleDatabase12cDataRedaction

OracleDatabaseOnlineDocumentation12cRelease1(12.1)/DatabaseAdministration

URL/TheDBMS_LOBpackageOracledatabasesecurity

about/OracleDatabaseSecurityoverviewOracledatabaseVault

about/OracleDatabaseSecurityoverviewOracleKeyVault(OKV)

about/OracleDatabaseSecurityoverviewOracleSecureFiles

deduplication/Deduplicationandcompressioncompression/Deduplicationandcompressionfilesystemlogging/FileSystemLoggingWriteGatherCache(WGC)/WriteGatherCachefreespacemanagement/FreespacemanagementandBasicFiles/BasicFilesandSecureFilesdb_securefileparameter/Thedb_securefileparameter

OracleSQLDeveloperabout/OracleSQLDeveloperforDBA/OracleSQLDeveloperforDBA,Developers,andApplicationArchitectsfordevelopers/OracleSQLDeveloperforDBA,Developers,andApplicationArchitectsforapplicationarchitects/OracleSQLDeveloperforDBA,Developers,andApplicationArchitectsSQLDeveloper4.0/SQLDeveloper4.0

OracleSQLDeveloperExchangeprogramURL/Keydifferentiators

PPaymentCardIndustryDataSecurityStandard(PCI-DSS)/OracleDatabaseSecurityoverviewpersistentLOB/PersistentandTemporaryLOBPGA(ProcessGlobalArea)/DifferencesbetweenResultCacheandothercachingtechniquesPL/Scopetool

about/ThePL/ScopetoolPLSCOPE_SETTINGSparameter/ThePLSCOPE_SETTINGSparameter

PL/SQLabout/IntroductiontoPL/SQLadvantages/IntroductiontoPL/SQLaccomplishments/IntroductiontoPL/SQLprogram,fundamentals/PL/SQLprogramfundamentalsblock/PL/SQLprogramfundamentalsexceptionhandling/ExceptionhandlinginPL/SQLenhancements/MiscellaneousPL/SQLenhancementscollectionmethods/PL/SQLcollectionmethodsexternalCprograms,executing/ExecutingexternalCprogramsfromPL/SQLJavaprograms,executing/ExecutingJavaprogramsfromPL/SQLbulkprocessing/BulkprocessinginPL/SQL

PL/SQLblockanonymousPL/SQLblock/PL/SQLprogramfundamentalsnamed/PL/SQLprogramfundamentalsnested/PL/SQLprogramfundamentals

PL/SQLcodetuning/TuningPL/SQLcodesecureapplicationsbuilding,bindvariablesused/Buildsecureapplicationsusingbindvariablesparameters,callingbyreference/Callparametersbyreferenceimplicitdatatypeconversion,avoiding/AvoidinganimplicitdatatypeconversionNOTNULLconstraint/UnderstandingtheNOTNULLconstraintnumericdatatype,selecting/Selectionofanappropriatenumericdatatype

PL/SQLcode,designingcursorstructures/Cursorstructurescursorvariables/Cursorvariablessubtypes/Subtypes

PL/SQLcode,profilingabout/ProfilingPL/SQLcodeDBMS_HPROFpackage/TheDBMS_HPROFpackagerawprofiledata,collecting/Collectingrawprofiledataprofilerdata,analyzing/Analyzingprofilerdata

plshprofutility/TheplshprofutilityPL/SQLcodinginformation,tracking

about/TrackingPL/SQLcodinginformationUSER_ARGUMENTSview/USER_ARGUMENTSUSER_OBJECTSview/USER_OBJECTSUSER_OBJECT_SIZEview/USER_OBJECT_SIZEUSER_SOURCEview/USER_SOURCEUSER_PROCEDURESview/USER_PROCEDURESUSER_PLSQL_OBJECT_SETTINGSview/USER_PLSQL_OBJECT_SETTINGSandUSER_STORED_SETTINGSUSER_STORED_SETTINGSview/USER_PLSQL_OBJECT_SETTINGSandUSER_STORED_SETTINGSUSER_DEPENDENCIESview/USER_DEPENDENCIESDBMS_DESCRIBEpackage/TheDBMS_DESCRIBEpackageprogramexecutionsubprogramcallstack,tracking/TrackingtheprogramexecutionsubprogramcallstackpropagatingexceptionsinPL/SQLcode,tracking/TrackingpropagatingexceptionsinPL/SQLcode

PL/SQLcompilerabout/ThePL/SQLCompilersubprograminlining/SubprograminlininginPL/SQL

PL/SQLEditorandDebuggerabout/PL/SQLEditorandDebugger

PL/SQLfunctionresultcacheabout/PL/SQLFunctionResultCache,Doesitsoundsimilartodeterministicfunctions?andothercachingtechniques,differences/DifferencesbetweenResultCacheandothercachingtechniquesillustration/Illustrationmonitoring/MonitoringthePL/SQLResultCacheinvalidation/InvalidationofthePL/SQLResultCachelimitations/Limitation

PL/SQLinterpretedcompilationdatabase,recompiling/RecompilingadatabaseforaPL/SQLnativeorinterpretedcompilation

PL/SQLnativecompilationdatabase,recompiling/RecompilingadatabaseforaPL/SQLnativeorinterpretedcompilation

PL/SQLpackageabout/APL/SQLpackage

PL/SQLprogramunitwhitelisting/ThePL/SQLprogramunitwhitelisting

PL/SQLprogramssample/AsamplePL/SQLprogram

tracing,DBMS_TRACEused/TracingPL/SQLprogramsusingDBMS_TRACEDBMS_TRACEpackage,installing/InstallingtheDBMS_TRACEpackageDBMS_TRACEsubprograms/DBMS_TRACEsubprogramscompiling,fordebugging/CompilingaPL/SQLprogramfordebuggingPL/SQLtraceinformation,viewing/ViewingthePL/SQLtraceinformationexecution,tracing/StepstotracePL/SQLprogramexecutionprofiling/ProfilingPL/SQLcode

PL/SQLprogramunitsroles,granting/GrantingrolestoPL/SQLprogramunitstestsetup/Testsetup

PL/SQLsubprogramdefining,inSELECTquery/DefiningaPL/SQLsubprogramintheSELECTqueryandPRAGMAUDFdefining,inPRAGMAUDF/DefiningaPL/SQLsubprogramintheSELECTqueryandPRAGMAUDFtestsetup/Testsetupcomparativeanalysis/Comparativeanalysis

PL/SQLvirtualmachine(PVM)/Nativeandinterpretedcompilationtechniquesplshprofutility

about/Theplshprofutilityreports,exploring/Whatdothesereportsreveal?

PLSQL_OPTIMIZE_LEVELabout/PLSQL_OPTIMIZE_LEVELcases/Case1:WhenPLSQL_OPTIMIZE_LEVEL=0,Case2:WhenPLSQL_OPTIMIZE_LEVEL=1,Case3:WhenPLSQL_OPTIMIZE_LEVEL=2,Case4:WhenPLSQL_OPTIMIZE_LEVEL=3

pluggabledatabase(PDB)about/DatabaseconsolidationandthenewMultitenantarchitecture

/Rapidprovisioningpluggabledatabases

about/DatabaseconsolidationandthenewMultitenantarchitecturePRAGMAINLINE

about/PRAGMAINLINEPRIORfunction/PRIORandNEXTprofilerdata

analyzing/Analyzingprofilerdataprofilertables,creating/Creatingtheprofilertablesprofileroutput,analyzing/Analyzingtheprofileroutputprofilertables,querying/Queryingtheprofilertables

RRAC(RealApplicationClusters)

features/ResultcacheinRealApplicationClustersRAISE_APPLICATION_ERRORprocedure/TheRAISE_APPLICATION_ERRORprocedurerawprofiledata

collecting/Collectingrawprofiledatainterpreting/Interpretingtherawprofilerdata

RealApplicationCluster(RAC)/NativeandinterpretedcompilationtechniquesRealApplicationClusters(RAC)

resultcache/ResultcacheinRealApplicationClustersRealApplicationSecurity(RAS)

about/OracleDatabaseSecurityoverviewredologs/DatabaseconsolidationandthenewMultitenantarchitectureRemote-Ops(RO)/TNSNAMES.oraResultCache

SQLqueryresultcache/OracleDatabase11gResultCachePL/SQLfunctionresultcache/OracleDatabase11gResultCacheOCIresultcache/OracleDatabase11gResultCacheversusBufferCache/ResultCacheversusBufferCacheversusDatabaseIn-Memory/ResultCacheversusOracle12cDatabaseIn-MemoryversusIn-MemoryDatabaseCache(IMDB)/ResultCacheversusIn-MemoryDatabaseCache

SSCN(systemchangenumber)/ReadconsistencyoftheSQLResultCacheSDDM(SQLDeveloperDataModeler)/SQLDeveloperforDatabaseAdministratorsSDK(softwaredevelopmentkit)/AnoverviewofSQLDeveloperServerResultCache

about/OracleDatabase11gResultCache,WhatistheServerResultCache?configuring/ConfiguringtheServerResultCache

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SingleInstructionMultipleData(SIMD)/PerformanceoptimizationsSQLcl

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SQLDeveloperoverview/AnoverviewofSQLDeveloperhistory/Historyandbackgroundbackground/Historyandbackgroundreleases/Historyandbackgroundfordevelopers/SQLDeveloperforDevelopersfordatabaseadministrators/SQLDeveloperforDatabaseAdministratorsworkingwith/GettingstartedwithSQLDeveloperdatabaseconnection,creating/Creatingadatabaseconnectionfeatures/CorefeaturesofSQLDeveloper

SQLDeveloper4.1enhancements/SQLDeveloper4.0and4.1NewFeatures

SQLDeveloperDataModeler(SDDM)/OracleSQLDeveloperforDBA,Developers,andApplicationArchitectsSQLDeveloperExtensionsExchange

URL/AnoverviewofSQLDeveloperSQLDeveloperreports

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keyfactors,fordifferentiatingfromothertools/KeydifferentiatorsSQLinjection

about/WhatisSQLinjection?targets/SQLinjectiontargetsPL/SQLcode,exploiting/HowtoexploitthePL/SQLcode?

SQLinjection,attackspreventing/PreventingSQLinjectionattacksinputssanitizing,DBMS_ASSERTused/Sanitizinginputsusing

DBMS_ASSERTrightsubprogram,selectingforrightidentifier/ChoosetherightsubprogramfortherightidentifierDBMS_ASSERT,limitatiions/DBMS_ASSERT–limitationspreventing,bindvariablesused/Useofbindvariablestopreventinjectionattackspreventing,bestpractices/BestpracticestoavoidSQLinjection

SQLinjection,codetestingstrategy/Teststrategyreview/Aneffectivecodereviewstaticcodeanalysis/Staticcodeanalysisfuzztools/Fuzztoolstestcases,generating/Generatingtestcases

SQLqueryresultcacheabout/SQLqueryResultCachemonitoring/MonitoringtheSQLResultCacheinvalidation/InvalidationoftheSQLResultCachereadconsistency/ReadconsistencyoftheSQLResultCachelimitations/Limitations

SQLTranslationFrameworkabout/TheSQLTranslationFramework

SQLworksheetusing/UsingtheSQLworksheeticons/UsingtheSQLworksheetfunctionalities/UsingtheSQLworksheet

storedprocedurescreating/Creatingstoredproceduresexecuting/Executingaprocedure

subprograminliningPRAGMAINLINE/PRAGMAINLINEPLSQL_OPTIMIZE_LEVEL/PLSQL_OPTIMIZE_LEVEL

subtypeabout/Subtypesclassifying/Subtypeclassificationtypecompatibility/Typecompatibilitywithsubtypes

SYSAUXtablespace/DatabaseconsolidationandthenewMultitenantarchitecturesystem-definedexceptions

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TtemporaryLOB/PersistentandTemporaryLOBTEMPtablespace/DatabaseconsolidationandthenewMultitenantarchitectureTotalRecallfeature/TemporaldatabasesTransparentDataEncryption(TDE)/OracleDatabaseSecurityoverview,EncryptionTRIMfunction/TRIM

UUNDOtablespace/DatabaseconsolidationandthenewMultitenantarchitectureuser-definedexceptions

RAISE_APPLICATION_ERRORprocedure/TheRAISE_APPLICATION_ERRORprocedure

userglobalarea(UGA)/CursorstructuresUserGlobalArea(UGA)/Cursors–anoverview,ApplicationContext

Vvarray

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VirtualPrivateDatabase(VPD),componentsapplicationcontext/ApplicationContextpolicyfunction/VirtualPrivateDatabasepolicyfunctionpolicytype/PolicytypesDBMS_RLSpackage/TheDBMS_RLSpackage

WWriteGatherCache(WGC)/WriteGatherCache

Advanced Oracle PL/SQL Developer’s - irantuto.comirantuto.com/upload/Oracle/books/advanced_oracle_plsql_developers... · Table of Contents Advanced Oracle PL/SQL Developer’s Guide

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