ABAP Performance Check

7/30/2019 ABAP Performance Check

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ABAP Performance Check & Code Review Check List

By Debesh Page 1

Normally in every project after the developer completes a development he fills the review

check list and does some performance tests before sending it for lead review. The basic

check list template is attached at the end.

1. Extended Program Check / SLIN Test.After development the developer does a syntax check and after that the very first

test he/she executes is the SLIN Test. Display the program and from Program follow

the path as follows.

Check the items and execute.


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There should be ZERO errors/warnings/messages. Click on the red markederrors/warnings and go to the code and make the proper corrections.

After achieving zero errors/messages/warnings go to Code Inspector check from thesame path.

2. Code Inspector CheckIt does a static analysis before we run the program and reports potential

performance issues.

Although it does not provide any relevant information about the code during runtime

but still it checks for certain coding standards like :

- In where clause all key fields are used or not, and whether sy-subrc check isused after database statements or not.


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Try to remove all errors and warnings .Expand the section , double click the item , it

will take you to the code and take proper action.

To improve the performance and quality of code, SAP has provided somePerformance Analysis tools. They are mentioned below.

3. Run time analysis (transaction SE30)It is used by the developer to calculate or evaluate the quality of the code to

achieve the business requirement. It ensures the performance of program on

Production server.Execution time for the code

Evaluation of the 3 main areas:ABAP

DatabaseSystem

Go To Transaction SE30 and provide the program name and execute.


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It will take you to the program selection screen.

Provide a parameter or choose a variant and execute.

Go back from the result screen to the se30 screen.

It will display a message for run time analysis completion. Click on evaluate.


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It will display the time spend on application server level and data base level.

System and Data base section should be small.

Go to Hit List.

The Hit list summarizes the measurements of execution and processing times into

one entry per operation. Filter Hit List.

Choose from the available options for which the analysis is important.


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Now check in which statements more time is being spent and go back to code andcheck whether these code can be made more efficient or not.

From the main run time analysis menu you can go to tips & tricks.

There you can check how same staments written in two different ways can changethe run time significantly. Choose any option and comapare and measure the

runtime.


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4. SQL Trace (ST05).It accesses the DDIC compenents to check SQL statement performances, Lockingactivities, Remote calls etc.

Go to transaction ST05. Make trace on.


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Run the program and then do trace off.


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Now click on display trace.

It shows the sequence of database operations that are taking place while a query isprocessed.It includes prepare, fetch, open, reopen, execute.


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Now you can have a detailsed list or can make a summery out of it.

There are certain other tools like New Version of Runtime Analysis tool (Transaction

SAT), ST12 (SQL trace, ABAP Trace, Enqueue, RFC all at one place ), STAD etc.

Certain Recommended Coding Standards:

1. Properly document each development with Developer name and change history.2. Follow certain naming conventions (like local variaable lv_name, global variable

gv_name, woel area ls_name , constants c_name and so on).

3. Remove dead codes.4. When possible use MOVE instead of MOVE-CORRESPONDING .5. Code executed more than once should be placed in a form routine.6. Use SORT and READ TABLE t_tab WITH KEY ... BINARY SEARCH when possible .7. Use all key fields for Select Single else use Select up to one row.8. Do a table is empty or not check before For all entries addition.9. Views (inner join) are a fast way to access information from multiple tables.

Use subqueries when possible.

10.Where clause should be in order of index See example.Where clause should contain key fields in an appropriate db index or buffered tables.

11.Avoid nested SELECTs (SELECT...ENDSELECT within another SELECT...ENDSELECT).12.Use CASE statement instead of IF...ELSEIF when possible (It is only possible in

equality tests).
http://web.mit.edu/fss/dev/sample_code.htm#Sort%20and%20READ%20TABLEhttp://web.mit.edu/fss/dev/covp.htmhttp://fuller.mit.edu/hr/complex_subquery.htmlhttp://web.mit.edu/fss/dev/select_examples.htm#optimizer%20quirkhttp://web.mit.edu/fss/dev/select_examples.htm#optimizer%20quirkhttp://web.mit.edu/fss/dev/sample_code.htm#rules%20basedhttp://web.mit.edu/fss/dev/select_examples.htm#Select%20Statement%20Where%20Clause%20ahttp://web.mit.edu/fss/dev/sap_table_types.htm#Buffered%20Tableshttp://web.mit.edu/fss/dev/sample_code.htm#Case%20Statementhttp://web.mit.edu/fss/dev/sample_code.htm#Case%20Statementhttp://web.mit.edu/fss/dev/sample_code.htm#Case%20Statementhttp://web.mit.edu/fss/dev/sap_table_types.htm#Buffered%20Tableshttp://web.mit.edu/fss/dev/select_examples.htm#Select%20Statement%20Where%20Clause%20ahttp://web.mit.edu/fss/dev/sample_code.htm#rules%20basedhttp://web.mit.edu/fss/dev/select_examples.htm#optimizer%20quirkhttp://fuller.mit.edu/hr/complex_subquery.htmlhttp://web.mit.edu/fss/dev/covp.htmhttp://web.mit.edu/fss/dev/sample_code.htm#Sort%20and%20READ%20TABLE


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Code Review Check List

DescriptionResult

(Y, N orN/A)

Comments

Run Extended syntax checks with character literals

checkbox switched on & Code Inspector to rectify allrelevant errors and warning (e.g. Use the results of the

above checks to remove all variables/constants etc that

are declared but are not used)

Transaction SE30 (ABAP Runtime Analysis) must be

checked to measure/compare programperformance/runtime if program has multiple inefficientdatabases selects or complicated internal table operations

Use transaction ST05 (SQL Trace) to see what indicesyour database accesses are using. Check these indices

against your where clause to assure they are significant.Check other indices for this table and where you have to

change your where clause to use it. Create new indicesif necessary, but do not forget to check the impact byconsulting onsite coordinator.

TYPE (data element) command is used while declaring the

fields whenever feasible instead of LIKE. Remember notalways the data element name matches with the table

field name

Internal Table is defined with TYPE STANDARD TABLEOF & Work-Areas is used instead of header lines

Global variables are minimized by declaring local variablesor by passing variables through parameters & arguments

while creating internal subroutine(s)

In SELECT statement, only the required fields are selectedin the same order as they reside on the database

table/structure/view

For selecting single row from a database table, SELECTUP to 1 Rows is used. Select Single is used only when

full primary key combination is known

No SELECT * is used

Use SELECT INTO TABLE rather than SELECT INTOCORRESPONDING FIELDS OF TABLE

Always specify as many primary keys as possible inWHERE clause to make the Select efficient

Always select into an internal table, except when the table

will be very large (i.e., when the internal table will be

greater than 500,000 records). Use Up to N Rows whenthe number of records needed is known

Select statement within a GET event is not used

Wild cards like A% is avoided as much as possible

Nested Select is not used instead Inner Join and/or For

all Entries is used. For all Entries is to be used overLoop at ITAB / Select / ENDLOOP (FOR ALL ENTRIES

retrieves a unique result set so ensure you retrieve thefull key from the database)


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When creating joins over database tables there should be

an index at least on the inner table for the fields in the

join condition else use FOR ALL ENTRIES selectstatement

Usage of JOIN is limited to a maximum of 2 i.e. not more

than 3 database tables are joined at one time

CHECK that the internal table used in FOR ALL ENTRIES isNOT empty as this will retrieve all entries from the table

Delete adjacent duplicate entries from internal table

before selection from database table using FOR ALL

ENTRIES statement

For copying internal tables use = operator instead of

Looping & Appending

SORT inside a LOOP is not used

Sort internal table by fields in the correct order, which areused in a READ TABLE statement using BINARY SEARCH.If the order of sorting is invalid the BINARY SEARCH will

never work

For large internal tables where only some rows are to beprocessed, use SORT and then the READ TABLE command

is used to set index to first relevant row before loopingfrom that index. Use CHECK or IFEXITENDIF asappropriate to exit from the loop

Sort fields and Sort Order on the SORT statement shouldbe mentioned explicitly (e.g. SORT ITAB BY FLD1 FLD2

ASCENDING)

Hashed table is used for processing large amount of data(provided that you access single records only, and all with

a fully specified key)

DELETE or SORT is not used on a hashed table since it

increases memory consumptionSorted table is used for range accesses involving table

key or index accesses

Fields specified in the WHERE condition with the critical

operators NOT and (negative SQL statements) cannot

be used for a search using database indexes. Wheneverpossible formulate SQL statements positively

When coding IF or CASE, testing conditions are nested so

that the most frequently true conditions are processedfirst. Also CASE is used instead of IF when testing

multiple fieldsequal to something

LOOP AT ITAB INTO WORKAREA WHERE K = XXX shouldbe used instead of LOOP AT ITAB INTO WORKAREA /

CHECK ITAB-K = XXX.

Also READ TABLE INTO WORKAREA should be used

instead of only READ TABLE.

After the APPEND statement inside a loop, the work area

that has been appended is cleared

Internal tables, Work areas & Global Variables are freed

when no longer needed (e.g. using the FREE / REFRESH


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command), especially when the tables are large or the

program is a batch program

Do not delete the records of internal table inside the Loop End loop.

Do not use:LOOP AT ITAB WHERE EQUNR = 00001011.

DELETE ITAB.

ENDLOOP.

Use:DELETE ITAB WHERE EQUNR = 00001011.

Use the MODIFY ITAB ... TRANSPORTING f1 f2 ... forsingle line, and MODIFY ITAB ... TRANSPORTING f1 f2 ...

WHERE condition for a set of line, to accelerate the

updating of internal table

If possible, Update/Insert statement is used instead ofModify

Is the following steps ensured during database updates?

Lock data to be edited Read current data from the database Process data and write it to the database Release the locks set at the beginning

Try to avoid logical databases. If your program uses alogical database, but does not require all fields belonging

to a certain GET event, always use the FIELDS addition to

reduce the amount of data selected by the logicaldatabase

Avoid the aggregate (Count, Max, Min) functions in thedatabase selection

Use Parallel Cursor methods for nested loop into the

internal tables if second internal table containsconsiderable number of records

In Smartform/ Sapscript do not make redundant data

retrieval where data is available in interface

Check List(2)

Description Result Comment

Title

The title is a concise description

Type

Thetypeof program is specified correctly

Status:


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'P' SAP standard production program

'K' Custom-developed program for production

'T' Test Program

'S' System Program

Application

The application area should relate back to Character

Module Identification he program name.

Authorization Group

The appropriate authorization group has been used

Development Class

The appropriate development class has been used

Name Space

The appropriate namespace has been used

Documentation:

Documentation Block:

Must contain:

Description: Detailed description

Created By: Developers name

Created On: Date

Program Documentation for FM

The OnlineProgram Documentationprovides functional

leads and end users with necessary information to

determine report functionality. It also contains

information on file inputs and outputs

Code Comments


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Internal commenting has been done sufficiently enough

to ease program maintenance and reliability of the ABAP

Change History

A chronological history of modification notes; with the

latest change being the last entry in the modification log.

Include Transport Number.

Naming Standards:

The ABAP/4 Naming Standards and Programming

Standards have been followed in naming objects and

components in the program.

Variables

TYPE preferred to LIKE

Constants

Internal Tables

Select Options

Parameters

Program Name

Hardcoding?

TYPES:

Types used appropriatelyQuality:

Event Structure

The standard structure for ABAP/4 report coding has

been followed as outlined in the Programming Standards

documentation

SY-SUBRC

SY-SUBRC is checked after database activities to ensure

proper inputs when dealing with tables (for example:

READ, SELECT, INSERT)

WHEN OTHERS with CASE


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All CASE statements must have WHEN OTHERS to

capture unexpected errors

Code Inspector

Follow menu path: Program, Check, Code Inspector.

Check to see if any performance improvement

opportunities.

Extended Syntax Check

An extended syntax check has been run on the ABAP

Perform Syntax Check on the Transport.

Run-time Trace Analysis (transaction SE30)

The run-time analysis tool has been used to evaluate the

hit lists of the top CPU consumers, table accesses, and to

get a general idea of the coding run during the program

execution.

SQL Trace (ST05)

SQL calls have been checked through the SQL Trace and

Execution Plan to check efficiency

Programming Standards / Program Optimization:

Text Elements

Each ABAP should have associated text elements and

selection texts from the source code placed within the

Text Elements section

Range Tables

For defining internal tables with the same structure as

selection tables, the RANGES statement should be used.

Selection Screen:

Validate the field(s) as much as possible from the

corresponding main table. If invalid, give error such as

Invalid XXXX.

Error Messages:

Validate that there are no hard errors in the code. Hard

errors (Message E000 with XXX) are ok for the selection


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screen, but in the code after START OF SELECTION, the

error should be written to the screen & the code should

be stopped if no further processing should be done. This

will prevent the batch job from canceling & will write the

error to the spool.

SQL Interfaces:

SELECT INTO preferred to SELECT APPEND

ENDSELECT

When an internal table needs to be created directly

from one database table, the SELECT INTO is used to

fill the internal table. It is faster to use the INTO

TABLE version of a SELECT statement than to use

APPEND statements

WHERE clause:

For Transparent or POOL tables, the SELECT

statement is as fully qualified as possible with the

WHERE option, including data fields that are not part of

the key

For Cluster tables, only the fields that are part of the

key are qualified in the WHERE option. The CHECK

command is used to eliminate other records.

The ordering of the WHERE statements match thearrangement of the keys in the table records

Fields compared in the WHERE clause of SELECT

statements have similar types

The use of negative logic in SELECTs is avoided

whenever possible

When using the AND or OR operator the most likely

elimination criteria is specified first. (Expressions are

evaluated left to right and the evaluation ends when

the final result has been established)

Primary Key Used

Whenever possible, the full table key is specified and

SELECT SINGLE is specified


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Secondary Index Usage

When possible, in the WHERE clause the fields of the

INDEX are in the specified order and linked by the

logical AND with comparisons for equality.

A secondary index has been considered if:

Non-key fields or fields for which index supportdoes not exist are repeatedly used to make

selections Only a small part of a large table is selected

(


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SELECT statement

Preferred:

SELECT FIELD1 FROM TABLEUP TO 1 ROWS.

ENDSELECT.

Avoid:

SELECT FIELD1 FROM TABLE.

EXIT.

ENDSELECT.

Sorting

SORT ITAB ORDER BY preferred over SORT ITAB

Delete Adjacent Duplicates

SORT the internal table according to ALL

the fields that you want to compare

when looking for duplicates before using

delete adjacent duplicates.

Aggregates

When finding aggregates such as maximum, minimum

sum, average, and count, a SELECT list with the

aggregate function is used instead of programming the

code.

Internal Tables

Nested Loops

Nested loops are avoided. If unavoidable, takeadvantage of parallel cursor technique

Unnecessary MOVEs are avoided by using explicit

Work Areas

Reading:


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LOOPWHERE is used instead of LOOP/CHECK

For READ operations, the key fields are specified for

READ access explicitly

When performing BINARY search, the internal table

must be first sorted by the key.

BINARY SEARCH

When the read command is used, the table is

sequentially searched. This slows down the processing.

Instead of this, use the binary search addition. The

binary search algorithm helps faster search of a value

in an internal table. Binary search repeatedly divides

the search interval in half. If the value to be searched

is less than the item in the middle of the interval, the

search is narrowed to the lower half; otherwise the

search is narrowed to the upper half.

REFRESH

REFRESH table is used to initialize table records

FREE

The FREE command is used to release the memoryallocated to internal tables when the program is

finished processing the data in the table and when the

following conditions exist:

The internal table is large The internal table is sorted and reprocessed several

times

Program is processing several internal tablesOCCURS

A number other than zero is only specified for the

OCCURS parameter is the required storage is less than8 kilobytes

SORT:

All SORT statements are qualified with the BY option

and limited to the fields that must be used to satisfy

processing requirement


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Modularization:

Break code in to logical segments for modularization

into subroutines whenever possible.

Listed in order of best performance. Be sure the

modularization is worth the extra run-time required.

PERFORM

Cost/Run-time: Factor 1 (Note: this is the base factor

for the techniques to follow)

CALL FUNCTION

Cost/Run-time: Factor 12

Optimization:

General:

All LOOPs, IFs, CASEs, and similar statements are

broken down to their simplest form and nesting is not

complicated unless absolutely necessary

All unused variables and program parts are removed

from the program

MOVE

When possible, the destination operands are kept as

the same data type as the source operands

CASE preferred to IF

IF

When using the AND or OR operator the most likely

elimination criterion is specified first.

WHILE preferred to DO

CLEAR field for Initialization:

CLEAR fieldis used to initialize rather than explicit

moves

Table headers and work areas are CLEAR at the end

of loop process


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MOVE CORRESPONDING:

MOVE CORRESPONDING is only used for small tables or

tables where most, but not all, fields need to be

moved.

Try to avoid using INTO CORRESPONDING FIELDS OF

TABLE. Instead use INTO TABLE.

When all fields need to be moved and the attributes

for every field and position are identical, the table is

MOVEed as a group.

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