Steven Feuerstein - Programming With Collections
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Copyright 2000-2009 Steven Feuerstein - Page 1
Collect Yourself:
Optimize PL/SQL Code with
Collections
Steven FeuersteinPL/SQL Evangelist, Quest Software
steven.feuerstein@quest.com
www.ToadWorld.com/SF
PL/SQL Webinars for Oracle Education
Copyright 2000-2006 Steven Feuerstein - Page 2
How to benefit most from this session
Watch, listen, focus on concepts and principles.
Download and use any of my the training materials:
You have my permission to use all these materials to do internal trainings and build your own applications.– But remember: they are not production ready.
– Modify them to fit your needs and then test them!
filename_from_demo_zip.sql
Download and use any of my scripts (examples, performance scripts, reusable code) from the same location: the demo.zip file.
http://www.ToadWorld.com/SFPL/SQL Obsession
Copyright 2000-2008 Steven Feuerstein - Page 3
What we will cover on collections
Review of "foundation" features
Indexing collections by strings
Working with collections of collections
MULTISET operators for nested tables
Then we will apply collections (overview):
– Data caching
– Bulk processing with FORALL and BULK COLLECT
– Table functions and pipelined functions
Copyright 2000-2006 Steven Feuerstein - Page 4
What is a collection?
A collection is an "ordered group of elements, all of
the same type." (PL/SQL User Guide and Reference)
– That's a very general definition; from collections, you can
build queues, stacks, lists, sets, arrays.
– Collections are single-dimensional and homogeneous, but
you can emulate multi-dimensional structures.
Collections are a critical feature in many of the newest
and most important features of PL/SQL.
– Yet they are greatly underutilized by PL/SQL developers.
abc def sf q rrr swq...1 2 3 4 22 23
Copyright 2000-2006 Steven Feuerstein - Page 5
Why use collections?
Generally, to manipulate in-program-memory lists of
information.
– Much faster than working through SQL.
Serve up complex datasets of information to non-
PL/SQL host environments using table functions.
Dramatically improve multi-row querying, inserting,
updating and deleting the contents of tables. Combined with BULK COLLECT and FORALL....
Emulate bi-directional, random access cursors.
Avoid mutating table trigger errors.
Copyright 2000-2006 Steven Feuerstein - Page 6
Three Types of Collections
Associative arrays (aka index-by tables)
– Can be used only in PL/SQL blocks.
– Similar to hash tables in other languages, allows you to
access elements via arbitrary subscript values.
Nested tables and Varrays
– Can be used in PL/SQL blocks, but also can be the
datatype of a column in a relational table.
– Part of the object model in PL/SQL.
– Required for some features, such as table functions
– With Varrays, you specify a maximum number of elements
in the collection, at time of definition.
Copyright 2000-2006 Steven Feuerstein - Page 7
About Associative Arrays
Unbounded, practically speaking.
– Valid row numbers range from -2,147,483,647 to
2,147,483,647.
– This range allows you to employ the row number as an
intelligent key, such as the primary key or unique index
value, because AAs also are:
Sparse
– Data does not have to be stored in consecutive rows, as is
required in traditional 3GL arrays and VARRAYs.
Index values can be integers or strings (Oracle9i R2
and above).assoc_array_example.sql
collection_of_records.sql
Copyright 2000-2006 Steven Feuerstein - Page 8
About Nested Tables
No pre-defined limit on a nested table.
– Valid row numbers range from 1 to
2,147,483,647.
Part of object model, requiring initialization.
Is always dense initially, but can become
sparse after deletes.
Can be defined as a schema level type and
used as a relational table column type.
nested_table_example.sql
Copyright 2000-2006 Steven Feuerstein - Page 9
About Varrays
Has a maximum size, associated with its type.
– Can adjust the size at runtime in Oracle10g R2.
Part of object model, requiring initialization.
Is always dense; you can only remove
elements from the end of a varray.
Can be defined as a schema level type and
used as a relational table column type.
varray_example.sql
Copyright 2000-2006 Steven Feuerstein - Page 10
How to choose your collection type
Use associative arrays when you need to...– Work within PL/SQL code only
– Sparsely fill and manipulate the collection
– Take advantage of negative index values and string indexing
Use nested tables when you need to...– Access the collection inside SQL (table functions, columns in
tables)
– Want or need to perform high level set operations
Use varrays when you need to...– If you need to specify a maximum size to your collection
– Access the collection inside SQL (table functions, columns in tables).
Copyright 2000-2006 Steven Feuerstein - Page 11
Handy Collection Methods
Obtain information about the collection– COUNT returns number of rows currently defined in
collection.
– EXISTS returns TRUE if the specified row is defined.
– FIRST/LAST return lowest/highest numbers of defined rows.
– NEXT/PRIOR return the closest defined row after/before the specified row.
– LIMIT tells you the max. number of elements allowed in a VARRAY.
Modify the contents of the collection– DELETE deletes one or more rows from collection.
– EXTEND adds rows to a nested table or VARRAY.
– TRIM removes rows from a VARRAY.
Copyright 2000-2006 Steven Feuerstein - Page 12
Useful reminders for PL/SQL collections
Memory for collections comes out of the PGA (Process Global Area) or UGA (User Global Area)– One per session, so a program using collections can
consume a large amount of memory.
Use the NOCOPY hint to reduce overhead of passing collections in and out of program units.
Encapsulate or hide details of collection management.
Don't always fill collections sequentially. Think about how you need to manipulate the contents.
Try to read a row that doesn't exist, and Oracle raises NO_DATA_FOUND.
nocopy*.*
Copyright 2000-2006 Steven Feuerstein - Page 13
PL/SQL in Shared Memory
Session 1 memory
(PGA/UGA)
emp_rec emp%rowtype;
tot_tab tottabtype;
Session 2 memory
(PGA/UGA)
emp_rec emp%rowtype;
tot_tab tottabtype;
System Global Area (SGA) of RDBMS Instance
Shared Pool
Large Pool
Reserved Pool
show_empscalc_totals upd_salaries
Select *
from emp
Shared SQL
Pre-parsedUpdate emp
Set sal=...
Library cache
Session 1Session 2
plsql_memory*.*
Copyright 2000-2006 Steven Feuerstein - Page 14
How PL/SQL uses the SGA, PGA and UGA
The SGA contains information that can be shared across schemas connected to the instance.
– From the PL/SQL perspective, this is limited to package static constants.
The User Global Area contains session-specific data that persists across server call boundaries
– Package-level data
The Process Global Area contains session-specific data that is released when the current server call terminates.
– Local dataplsql_memory.pkg
plsql_memory_demo.sql
PACKAGE Pkg isNonstatic_Constant CONSTANT PLS_INTEGER := My_Sequence.Nextval;Static_Constant CONSTANT PLS_INTEGER := 42;
END Pkg;
Copyright 2000-2006 Steven Feuerstein - Page 15
Expanded indexing capabilities for associative arrays
Prior to Oracle9iR2, you could only index by BINARY_INTEGER.
You can now define the index on your associative array to be:– Any sub-type derived from BINARY_INTEGER
– VARCHAR2(n), where n is between 1 and 32767
– %TYPE against a database column that is consistent with the above rules
– A SUBTYPE against any of the above.
This means that you can now index on string values! (and concatenated indexes and...)
Copyright 2000-2006 Steven Feuerstein - Page 16
Examples of New TYPE Variants
All of the following are now valid TYPE declarations in Oracle9i Release 2– You cannot use %TYPE against an INTEGER column,
because INTEGER is not a subtype of BINARY_INTEGER.
DECLARE TYPE array_t1 IS TABLE OF NUMBER INDEX BY BINARY_INTEGER; TYPE array_t2 IS TABLE OF NUMBER INDEX BY PLS_INTEGER;TYPE array_t3 IS TABLE OF NUMBER INDEX BY POSITIVE;TYPE array_t4 IS TABLE OF NUMBER INDEX BY NATURAL;TYPE array_t5 IS TABLE OF NUMBER INDEX BY VARCHAR2(64);TYPE array_t6 IS TABLE OF NUMBER INDEX BY VARCHAR2(32767);TYPE array_t7 IS TABLE OF NUMBER INDEX BY
employee.last_name%TYPE;TYPE array_t8 IS TABLE OF NUMBER INDEX BY
types_pkg.subtype_t;
Copyright 2000-2006 Steven Feuerstein - Page 17
Working with string-indexed collections
The syntax is exactly the same, but you should keep this in mind:
– The datatype returned by FIRST, LAST, NEXT and PRIOR methods is VARCHAR2.
– The longer the string values, the more time it takes Oracle to "hash" that string to the integer that is actually used as the index value.
If you are indexing by integer and find that your values are getting close to the limits (2**31 - 1 or -2**31 + 1), convert to a string index. assoc_array*.sql
assoc_array_perf.tst
int_to_string_indexing.sql
genaa.sql
Copyright 2000-2006 Steven Feuerstein - Page 18
Practical application for string indexing
I need to keep track of names used in my program.
– Specifically, in Quest Code Tester, we generate test code
and declare variables. So I need to make sure that I do not
declare the same variable more than once.
There are lots of ways to do this, but string-indexed
collections make it really easy!
FOR indx IN 1 .. l_variables.COUNTLOOP
If varname_already_usedTHEN
-- DO NOTHINGELSE
add_variable_declaration;mark_varname_as_used;
END IF;END LOOP; Without string indexing:
string_tracker0.*
Copyright 2000-2006 Steven Feuerstein - Page 19
The String Tracker package (V1)
First iteration: I only need to maintain one list of
names.
CREATE OR REPLACE PACKAGE BODY string_trackerIS
TYPE used_aat IS TABLE OF BOOLEAN INDEX BY maxvarchar2_t;g_names_used used_aat;
FUNCTION string_in_use ( value_in IN maxvarchar2_t ) RETURN BOOLEANIS BEGIN
RETURN g_names_used.EXISTS ( value_in );END string_in_use;
PROCEDURE mark_as_used (value_in IN maxvarchar2_t) ISBEGIN
g_names_used ( value_in ) := TRUE;END mark_as_used;
END string_tracker;
string_tracker1.*
Copyright 2000-2006 Steven Feuerstein - Page 20
Multi-level Collections
Prior to Oracle9i, you could have collections of records or objects, but only if all fields were scalars.
– A collection containing another collection was not allowed.
Now you can create collections that contain other collections and complex types.
– Applies to all three types of collections.
The syntax is non-intuitive and resulting code can be quite complex.
Oracle9i
Copyright 2000-2006 Steven Feuerstein - Page 21
String Tracker Version 2
The problem with String Tracker V1 is that it
only supports a single list of strings.
– What if I need to track multiple lists
simultaneously or nested?
Let's extend the first version to support
multiple lists by using a string-indexed, multi-
level collection.
– A list of lists....
Copyright 2000-2006 Steven Feuerstein - Page 22
The String Tracker package (V2)
CREATE OR REPLACE PACKAGE BODY string_trackerIS
TYPE used_aat IS TABLE OF BOOLEAN INDEX BY maxvarchar2_t;TYPE list_of_lists_aat IS TABLE OF used_aat INDEX BY maxvarchar2_t;g_list_of_lists list_of_lists_aat;
PROCEDURE mark_as_used (list_in IN maxvarchar2_t
, value_in IN maxvarchar2_t, case_sensitive_in IN BOOLEAN DEFAULT FALSE) IS
l_name maxvarchar2_t := CASE case_sensitive_in WHEN TRUE THEN value_in
ELSE UPPER ( value_in ) END;BEGIN
g_list_of_lists ( list_in ) ( l_name) := TRUE;END mark_as_used;
END string_tracker;
string_tracker3.*
Copyright 2000-2006 Steven Feuerstein - Page 23
Other multi-level collection examples
Multi-level collections with intermediate records and objects.
Emulation of multi-dimensional arrays
– No native support, but can creates nested collections to get much the same effect.
– Use the UTL_NLA package (10gR2) for complex matrix manipulation.
Four-level nested collection used to track arguments for a program unit.
– Automatically analyze ambiguous overloading.
multdim*.*
ambig_overloading.sql
OTN: OverloadCheck
multilevel_collections.sql
Copyright 2000-2006 Steven Feuerstein - Page 24
Encapsulate these complex structures!
When working with multi-level collections, you can easily and rapidly arrive at completely unreadable and un-maintainable code.
What' s a developer to do?
– Hide complexity -- and all data structures -- behind small modules.
– Work with and through functions to retrieve contents and procedures to set contents.
cc_smartargs.pkb:
cc_smartargs.next_overloading
cc_smartargs.add_new_parameter
Copyright 2000-2008 Steven Feuerstein - Page 25
Nested Tables unveil their MULTISET-edness
Oracle10g introduces high-level set operations on nested tables (only).
– Nested tables are “multisets,” meaning that there is no inherent order to their elements and duplicates are significant.
You can now…
– Check for equality and inequality
– Perform UNION, INTERSECT and MINUS operations
– Check for and remove duplicates
Works with nested tables of scalars, records, objects.
Oracle10g
Copyright 2000-2008 Steven Feuerstein - Page 26
Check for equality and inequality
Just use the basic operators….and NULLs have the usual disruptive impact.
Oracle10g
DECLARETYPE clientele IS TABLE OF VARCHAR2 (64);group1 clientele := clientele ('Customer 1', 'Customer 2');group2 clientele := clientele ('Customer 1', 'Customer 3');group3 clientele := clientele ('Customer 3', 'Customer 1');
BEGINIF group1 = group2 THEN
DBMS_OUTPUT.put_line ('Group 1 = Group 2');ELSE
DBMS_OUTPUT.put_line ('Group 1 != Group 2');END IF;
IF group2 != group3 THENDBMS_OUTPUT.put_line ('Group 2 != Group 3');
ELSEDBMS_OUTPUT.put_line ('Group 2 = Group 3');
END IF;END;
10g_compare.sql
10g_compare2.sql
10g_compare_old.sql
Copyright 2000-2008 Steven Feuerstein - Page 27
UNION, INTERSECT, MINUS
Straightforward, with the MULTISET keyword.
Oracle10g
BEGINour_favorites :=
my_favorites MULTISET UNION dad_favorites;
our_favorites := my_favorites MULTISET UNION DISTINCT dad_favorites;
our_favorites := my_favorites MULTISET INTERSECT dad_favorites;
our_favorites := dad_favorites MULTISET EXCEPT my_favorites;
END;
10g_setops.sql
10g_string_nt.sql
10g_favorites.sql
10g*union*.sql
SQL: UNION
SQL: UNION ALL
SQL: INTERSECT
SQL: MINUS
Copyright 2000-2008 Steven Feuerstein - Page 28
Distinct sets of values
Use the SET operator to work with distinct values, and determine if you have a set of distinct values.
Oracle10g
DECLAREkeep_it_simple strings_nt := strings_nt ();
BEGINkeep_it_simple := SET (favorites_pkg.my_favorites);
favorites_pkg.show_favorites ('FULL SET', favorites_pkg.my_favorites);
p.l (favorites_pkg.my_favorites IS A SET, 'My favorites distinct?');p.l (favorites_pkg.my_favorites IS NOT A SET, 'My favorites NOT distinct?');
favorites_pkg.show_favorites ('DISTINCT SET', keep_it_simple);
p.l (keep_it_simple IS A SET, 'Keep_it_simple distinct?');p.l (keep_it_simple IS NOT A SET, 'Keep_it_simple NOT distinct?');
END;
10g_set.sql
10g_favorites.pkg
Copyright 2000-2008 Steven Feuerstein - Page 29
Collections vs. Global Temporary Tables
Global temporary tables cut down on the
overhead of working with persistent tables.
– And you can use the full power of SQL, which is
their main advantage over collections.
GTTs still require interaction with the SGA.
So collections will still be faster, but they will
use more memory.
– GTTs consume SGA memory.
global_temp_tab_vs_coll.sql
Applying Collections
Data caching using packaged data
Turbo-charged SQL with BULK COLLECT
and FORALL
Table functions
I offer light coverage of these topics, simply
to ensure that you know what is possible.
Copyright 2000-2006 Steven Feuerstein - Page 30
Page 31
Data Caching Options
Why cache data?
– Because it is static and therefore you want to avoid the performance overhead of retrieving that data over and over again.
Options for caching data:
– The SGA: Oracle does lots of caching for us, but it is not always the most efficient means.
– Package data structures: PGA memory has less access overhead than SGA.
– Oracle11g Function Result Cache
– Deterministic functions
Page 32
Packaged collection caching
Prior to Oracle 11g, the best caching option for
PL/SQL programs involves declaring a package-level
data structure.
– It persists for the entire session.
– Usually a collection, to store multiple rows of data.
Why query information from the database (SGA) if
that data does not change during your session?
– Trivial example: the USER function
– More interesting: static tables
Instead, load it up in a package variable!Very simple example:
thisuser.*
Copyright 2000-2006 Steven Feuerstein - Page 33
FunctionPGA
Data Caching with PL/SQL Tables
First access
Subsequent accesses
PGAFunction
Database
Not in cache;
Request data
from database
Pass Data
to Cache
Application
Application
Requests Data
Data retrieved
from cache Data returned
to application
Application
Application
Requests Data
Data returned
to application
Data retrieved
from cache
Database
Data found in
cache. Database
is not needed.
emplu.pkg
emplu.tst
11g_emplu*.*
Copyright 2000-2006 Steven Feuerstein - Page 34
Turbo-charge SQL with bulk processing statements
Improve the performance of multi-row SQL operations by an order of magnitude or more with bulk/array processing in PL/SQL!
CREATE OR REPLACE PROCEDURE upd_for_dept (dept_in IN employee.department_id%TYPE
,newsal_in IN employee.salary%TYPE)IS
CURSOR emp_cur ISSELECT employee_id,salary,hire_dateFROM employee WHERE department_id = dept_in;
BEGINFOR rec IN emp_cur LOOP
adjust_compensation (rec, newsal_in);
UPDATE employee SET salary = rec.salaryWHERE employee_id = rec.employee_id;
END LOOP;END upd_for_dept;
Row by row processing:
elegant but inefficient
Copyright 2000-2006 Steven Feuerstein - Page 35
Use the FORALL Bulk Bind Statement
Instead of executing repetitive, individual DML statements, you can write your code like this:
Things to be aware of with FORALL:– You MUST know how to use collections to use this feature!
– Only a single DML statement is allowed per FORALL.
– New cursor attributes: SQL%BULK_ROWCOUNT returns number of rows affected by each row in array. SQL%BULK_EXCEPTIONS...
– Prior to Oracle10g, the binding array must be sequentially filled.
– Use SAVE EXCEPTIONS to continue past errors.
PROCEDURE upd_for_dept (...) ISBEGIN
FORALL indx IN list_of_emps.FIRST .. list_of_emps.LASTUPDATE employee
SET salary = newsal_inWHERE employee_id = list_of_emps (indx);
END;
bulktiming.sql
bulk_rowcount.sql
bulkexc.sql
Copyright 2000-2006 Steven Feuerstein - Page 36
Use BULK COLLECT INTO for Queries
DECLARETYPE employees_aat IS TABLE OF employees%ROWTYPE
INDEX BY BINARY_INTEGER;
l_employees employees_aat;BEGIN
SELECT *BULK COLLECT INTO l_employeesFROM employees;
FOR indx IN 1 .. l_employees.COUNT LOOP
process_employee (l_employees(indx));END LOOP;
END;
bulkcoll.sql
Declare a
collection of
records to hold
the queried data.
Fetch all rows into
collection
sequentially, starting
with 1.
Iterate through the
collection
contents with a
loop. WARNING! BULK COLLECT will not raise
NO_DATA_FOUND if no rows are found.
Always check contents of collection to confirm that
something was retrieved.
Copyright 2000-2006 Steven Feuerstein - Page 37
Limit the number of rows returned by BULK COLLECT
CREATE OR REPLACE PROCEDURE bulk_with_limit (deptno_in IN dept.deptno%TYPE)
ISCURSOR emps_in_dept_cur IS
SELECT *FROM empWHERE deptno = deptno_in;
TYPE emp_tt IS TABLE OF emps_in_dept_cur%ROWTYPE;emps emp_tt;
BEGIN OPEN emps_in_dept_cur;LOOP
FETCH emps_in_dept_cur BULK COLLECT INTO emps LIMIT 100;
EXIT WHEN emps.COUNT = 0;
process_emps (emps);END LOOP;
END bulk_with_limit;
Use the LIMIT clause with the
INTO to manage the amount
of memory used with the
BULK COLLECT operation.
WARNING!
BULK COLLECT will not raise
NO_DATA_FOUND if no rows
are found.
Best to check contents of
collection to confirm that
something was retrieved.bulklimit.sql
Copyright 2000-2006 Steven Feuerstein - Page 38
The Wonder Of Table Functions
A table function is a function that you can call in the FROM clause of a query, and have it be treated as if it were a relational table.
Table functions allow you to perform arbitrarily complex transformations of data and then make that data available through a query.– Not everything can be done in SQL.
Combined with REF CURSORs, you can now more easily transfer data from within PL/SQL to host environments.– Java, for example, works very smoothly with cursor
variables
Copyright 2000-2006 Steven Feuerstein - Page 39
Simple table function example
Return a list of names as a nested table, and
then call that function in the FROM clause.
CREATE OR REPLACE FUNCTION lotsa_names (base_name_in IN VARCHAR2, count_in IN INTEGER
)RETURN names_nt
ISretval names_nt := names_nt ();
BEGINretval.EXTEND (count_in);
FOR indx IN 1 .. count_inLOOP
retval (indx) := base_name_in || ' ' || indx;
END LOOP;
RETURN retval;END lotsa_names;
tabfunc_scalar.sql
SELECT column_valueFROM TABLE (
lotsa_names ('Steven', 100)) names;
COLUMN_VALUE ------------Steven 1 ... Steven 100
Copyright 2000-2006 Steven Feuerstein - Page 40
Streaming data with table functions
You can use table functions to "stream" data
through several stages within a single SQL
statement.
– Example: transform one row in the stocktable to two
rows in the tickertable. CREATE TABLE stocktable (ticker VARCHAR2(20),trade_date DATE,open_price NUMBER,close_price NUMBER
)/CREATE TABLE tickertable (
ticker VARCHAR2(20),pricedate DATE,pricetype VARCHAR2(1),price NUMBER)
/
tabfunc_streaming.sql
Copyright 2000-2006 Steven Feuerstein - Page 41
Streaming data with table functions - 2
In this example, transform each row of the
stocktable into two rows in the tickertable.
CREATE OR REPLACE PACKAGE refcur_pkgIS
TYPE refcur_t IS REF CURSORRETURN stocktable%ROWTYPE;
END refcur_pkg;/
CREATE OR REPLACE FUNCTION stockpivot (dataset refcur_pkg.refcur_t)RETURN tickertypeset ...
BEGININSERT INTO tickertable
SELECT *FROM TABLE (stockpivot (CURSOR (SELECT *
FROM stocktable)));END;/
tabfunc_streaming.sql
Copyright 2000-2006 Steven Feuerstein - Page 42
Use pipelined functions to enhance performance.
Pipelined functions allow you to return data
iteratively, asynchronous to termination of the
function.
– As data is produced within the function, it is
passed back to the calling process/query.
Pipelined functions can be defined to support
parallel execution.
– Iterative data processing allows multiple
processes to work on that data simultaneously.
CREATE FUNCTION StockPivot (p refcur_pkg.refcur_t) RETURN TickerTypeSet PIPELINED
Copyright 2000-2006 Steven Feuerstein - Page 43
Applications for pipelined functions
Execution functions in parallel.
– In Oracle9i Database Release 2 and above, use the PARALLEL_ENABLE clause to allow your pipelined function to participate fully in a parallelized query.
– Critical in data warehouse applications.
Improve speed of delivery of data to web pages.
– Use a pipelined function to "serve up" data to the webpage and allow users to being viewing and browsing, even before the function has finished retrieving all of the data.
Copyright 2000-2006 Steven Feuerstein - Page 44
Piping rows out from a pipelined function
CREATE FUNCTION stockpivot (p refcur_pkg.refcur_t)RETURN tickertypesetPIPELINED
ISout_rec tickertype :=
tickertype (NULL, NULL, NULL);in_rec p%ROWTYPE;
BEGINLOOP
FETCH p INTO in_rec;EXIT WHEN p%NOTFOUND;out_rec.ticker := in_rec.ticker;out_rec.pricetype := 'O';out_rec.price := in_rec.openprice;
PIPE ROW (out_rec);END LOOP;CLOSE p;
RETURN;END;
tabfunc_setup.sql
tabfunc_pipelined.sql
Add PIPELINED
keyword to header
Pipe a row of data
back to calling block
or query
RETURN...nothing at
all!
Copyright 2000-2006 Steven Feuerstein - Page 45
Table functions – Summary
Table functions offer significant new flexibility
for PL/SQL developers.
Consider using them when you...
– Need to pass back complex result sets of data
through the SQL layer (a query);
– Want to call a user defined function inside a
query and execute it as part of a parallel query.
Copyright 2000-2009 Steven Feuerstein - Page 46
Collections – don't start coding without them.
It is impossible to write efficient, high quality
PL/SQL code, taking full advantage of new
features, unless you use collections.
– From array processing to table functions, collections are
required.
Today I offer this challenge: learn collections
thoroughly and apply them throughout your
backend code.
– Your code will get faster and in many cases much
simpler than it might have been (though not always!).
Some Useful URLs...
E-Attendance link http://education.oracle.com/eattendance.html
(Class id : 2347771)
Course Evaluation link https://eval.oracle.com
Instructor Feedback link :
https://ougbsapex.us.oracle.com/pls/ougbsapex/f?p=120:17
Copyright 2000-2009 Steven Feuerstein - Page 47
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