topic Re: PERFORMANCE in Application Development and Automation Discussions

PERFORMANCE

Former Member — Mon, 10 Jul 2006 09:51:01 GMT

HOW TO IMPROVE THE PERFORMANCE OF A PROGRAME

Re: PERFORMANCE

dani_mn — Mon, 10 Jul 2006 09:54:08 GMT

Always check the driver internal tables is not empty, while using FOR ALL ENTRIES

Avoid for all entries in JOINS

Try to avoid joins and use FOR ALL ENTRIES.

Try to restrict the joins to 1 level only ie only for tables

Avoid using Select *.

Avoid having multiple Selects from the same table in the same object.

Try to minimize the number of variables to save memory.

The sequence of fields in 'where clause' must be as per primary/secondary index ( if any)

Avoid creation of index as far as possible

Avoid operators like <>, > , < & like % in where clause conditions

Avoid select/select single statements in loops.

Try to use 'binary search' in READ internal table. Ensure table is sorted before using BINARY SEARCH.

Avoid using aggregate functions (SUM, MAX etc) in selects ( GROUP BY , HAVING,)

Avoid using ORDER BY in selects

Avoid Nested Selects

Avoid Nested Loops of Internal Tables

Try to use FIELD SYMBOLS.

Try to avoid into Corresponding Fields of

Avoid using Select Distinct, Use DELETE ADJACENT

Regards,

Wasim AHmed

Re: PERFORMANCE

Former Member — Mon, 10 Jul 2006 09:54:27 GMT

you can refer these links :

http://www.sapgenie.com/abap/performance.htm

Re: PERFORMANCE

Former Member — Mon, 10 Jul 2006 09:59:18 GMT

Hi Srinivas,

chk this

Re: PERFORMANCE

Former Member — Mon, 10 Jul 2006 10:04:36 GMT

Hi Srinivas,

1.Avoid select * statements...tht means try using field names insted of.

2.Always use the Where clause.

3. Avoid selecting useless data that you filter out later.

4. Avoid using complex WHERE clauses, since the system has to break them down into several individual statements for the DB Systems..

And we many more....

For tips on how to improve the performance of ABAPtasks use se30 transaction...

Please reward points if you find this as a right solution

Regards,

Harini

Re: PERFORMANCE

Former Member — Mon, 10 Jul 2006 10:37:01 GMT

Hi,

Follow the Tips & Tricks specified in SE30.

And try to check the runtime analysis of the program always.

Try to keep the database resource less than 30% in SE30.

Analyse the Hit List for more information on different sections of program execution time.

Regards,

Karthik.k

Re: PERFORMANCE

Former Member — Mon, 10 Jul 2006 10:43:36 GMT

Hai Srinivasa

Go through the following Document

Check the following Links

http://www.sapgenie.com/abap/performance.htm

http://www.thespot4sap.com/Articles/SAPABAPPerformanceTuning_PerformanceAnalysisTools.asp

check the below link

http://www.sap-img.com/abap/performance-tuning-for-data-selection-statement.htm

See the following link if it's any help:

http://www.thespot4sap.com/Articles/SAPABAPPerformanceTuning_PerformanceAnalysisTools.asp

Check also http://service.sap.com/performance

and

books like

http://www.sap-press.com/product.cfm?account=&product=H951

http://www.sap-press.com/product.cfm?account=&product=H973

http://www.sap-img.com/abap/more-than-100-abap-interview-faqs.htm

For all entries

Nested selects

Select using JOINS

Use the selection criteria

Use the aggregated functions

Select with view

Select with index support

Select … Into table

Select with selection list

Key access to multiple lines

Copying internal tables

Modifying a set of lines

Deleting a sequence of lines

Linear search vs. binary

Comparison of internal tables

Modify selected components

Appending two internal tables

Deleting a set of lines

Tools available in SAP to pin-point a performance problem

Optimizing the load of the database

For all entries

The for all entries creates a where clause, where all the entries in the driver table are combined with OR. If the number of entries in the driver table is larger than rsdb/max_blocking_factor, several similar SQL statements are executed to limit the length of the WHERE clause.

The plus

Large amount of data

Mixing processing and reading of data

Fast internal reprocessing of data

Fast

The Minus

Difficult to program/understand

Memory could be critical (use FREE or PACKAGE size)

Some steps that might make FOR ALL ENTRIES more efficient:

Removing duplicates from the driver table

Sorting the driver table

If possible, convert the data in the driver table to ranges so a BETWEEN statement is used instead of and OR statement:

FOR ALL ENTRIES IN i_tab

WHERE mykey >= i_tab-low and

mykey <= i_tab-high.

Nested selects

The plus:

Small amount of data

Mixing processing and reading of data

Easy to code - and understand

The minus:

Large amount of data

when mixed processing isn’t needed

Performance killer no. 1

Select using JOINS

The plus

Very large amount of data

Similar to Nested selects - when the accesses are planned by the programmer

In some cases the fastest

Not so memory critical

The minus

Very difficult to program/understand

Mixing processing and reading of data not possible

Use the selection criteria

SELECT * FROM SBOOK.

CHECK: SBOOK-CARRID = 'LH' AND

SBOOK-CONNID = '0400'.

ENDSELECT.

SELECT * FROM SBOOK

WHERE CARRID = 'LH' AND

CONNID = '0400'.

ENDSELECT.

Use the aggregated functions

C4A = '000'.

SELECT * FROM T100

WHERE SPRSL = 'D' AND

ARBGB = '00'.

CHECK: T100-MSGNR > C4A.

C4A = T100-MSGNR.

ENDSELECT.

SELECT MAX( MSGNR ) FROM T100 INTO C4A

WHERE SPRSL = 'D' AND

ARBGB = '00'.

Select with view

SELECT * FROM DD01L

WHERE DOMNAME LIKE 'CHAR%'

AND AS4LOCAL = 'A'.

SELECT SINGLE * FROM DD01T

WHERE DOMNAME = DD01L-DOMNAME

AND AS4LOCAL = 'A'

AND AS4VERS = DD01L-AS4VERS

AND DDLANGUAGE = SY-LANGU.

ENDSELECT.

SELECT * FROM DD01V

WHERE DOMNAME LIKE 'CHAR%'

AND DDLANGUAGE = SY-LANGU.

ENDSELECT.

Select with index support

SELECT * FROM T100

WHERE ARBGB = '00'

AND MSGNR = '999'.

ENDSELECT.

SELECT * FROM T002.

SELECT * FROM T100

WHERE SPRSL = T002-SPRAS

AND ARBGB = '00'

AND MSGNR = '999'.

ENDSELECT.

Select … Into table

REFRESH X006.

SELECT * FROM T006 INTO X006.

APPEND X006.

ENDSELECT

SELECT * FROM T006 INTO TABLE X006.

Select with selection list

SELECT * FROM DD01L

WHERE DOMNAME LIKE 'CHAR%'

AND AS4LOCAL = 'A'.

ENDSELECT

SELECT DOMNAME FROM DD01L

INTO DD01L-DOMNAME

WHERE DOMNAME LIKE 'CHAR%'

AND AS4LOCAL = 'A'.

ENDSELECT

Key access to multiple lines

LOOP AT TAB.

CHECK TAB-K = KVAL.

" ...

ENDLOOP.

LOOP AT TAB WHERE K = KVAL.

" ...

ENDLOOP.

Copying internal tables

REFRESH TAB_DEST.

LOOP AT TAB_SRC INTO TAB_DEST.

APPEND TAB_DEST.

ENDLOOP.

TAB_DEST[] = TAB_SRC[].

Modifying a set of lines

LOOP AT TAB.

IF TAB-FLAG IS INITIAL.

TAB-FLAG = 'X'.

ENDIF.

MODIFY TAB.

ENDLOOP.

TAB-FLAG = 'X'.

MODIFY TAB TRANSPORTING FLAG

WHERE FLAG IS INITIAL.

Deleting a sequence of lines

DO 101 TIMES.

DELETE TAB_DEST INDEX 450.

ENDDO.

DELETE TAB_DEST FROM 450 TO 550.

Linear search vs. binary

READ TABLE TAB WITH KEY K = 'X'.

READ TABLE TAB WITH KEY K = 'X' BINARY SEARCH.

Comparison of internal tables

DESCRIBE TABLE: TAB1 LINES L1,

TAB2 LINES L2.

IF L1 <> L2.

TAB_DIFFERENT = 'X'.

ELSE.

TAB_DIFFERENT = SPACE.

LOOP

AT TAB1.

READ TABLE TAB2 INDEX SY-TABIX.

IF TAB1 <> TAB2.

TAB_DIFFERENT = 'X'. EXIT.

ENDIF.

ENDLOOP.

ENDIF.

IF TAB_DIFFERENT = SPACE.

" ...

ENDIF.

IF TAB1[] = TAB2[].

" ...

ENDIF.

Modify selected components

LOOP AT TAB.

TAB-DATE = SY-DATUM.

MODIFY TAB.

ENDLOOP.

WA-DATE = SY-DATUM.

LOOP AT TAB.

MODIFY TAB FROM WA TRANSPORTING DATE.

ENDLOOP.

Appending two internal tables

LOOP AT TAB_SRC.

APPEND TAB_SRC TO TAB_DEST.

ENDLOOP

APPEND LINES OF TAB_SRC TO TAB_DEST.

Deleting a set of lines

LOOP AT TAB_DEST WHERE K = KVAL.

DELETE TAB_DEST.

ENDLOOP

DELETE TAB_DEST WHERE K = KVAL.

Tools available in SAP to pin-point a performance problem

· The runtime analysis (SE30)

· SQL Trace (ST05)

· Tips and Tricks tool

· The performance database

Optimizing the load of the database

Using table buffering

Using buffered tables improves the performance considerably. Note that in some cases a statement can not be used with a buffered table, so when using these statements the buffer will be bypassed. These statements are:

Select DISTINCT

ORDER BY / GROUP BY / HAVING clause

Any WHERE clause that contains a sub query or IS NULL expression

JOIN s

A SELECT... FOR UPDATE

If you wan t to explicitly bypass the buffer, use the BYPASS BUFFER addition to the SELECT clause.

Use the ABAP SORT Clause Instead of ORDER BY

The ORDER BY clause is executed on the database server while the ABAP SORT statement is executed on the application server. The database server will usually be the bottleneck, so sometimes it is better to move the sort from the database server to the application server.

If you are not sorting by the primary key ( E.g. using the ORDER BY PRIMARY key statement) but are sorting by another key, it could be better to use the ABAP SORT statement to sort the data in an internal table. Note however that for very large result sets it might not be a feasible solution and you would want to let the database server sort it.

Avoid the SELECT DISTINCT Statement

As with the ORDER BY clause it could be better to avoid using SELECT DISTINCT, if some of the fields are not part of an index. Instead use ABAP SORT + DELETE ADJACENT DUPLICATES on an internal table, to delete duplicate rows.

Thanks & regards

Sreenivasulu P

Message was edited by: Sreenivasulu Ponnadi

Re: PERFORMANCE

Former Member — Mon, 10 Jul 2006 11:24:42 GMT

Hi ,

You can use the following points in improving the performance..

Evaluate requirements

Communicate with users to get actual data required so that, default values could be set on Selection Screen. This would avoid extracting whole lot of data, which may not be really needed.

•Match the requirements.

1. Match the alternative source of information (in less populated tables).

2. Instead of Using cluster table, find the alternative transparent tables

3. Try to match the requirements with the views.

4. Check if the logical sequence of table access is correct. It is preferable to sequence the database access to go from a table with lesser values to the more populated tables.

•Improve access to Tables

1. As far as possible try to have direct accesses on records by providing full key, so that access would be faster.

2. Always specify your conditions in the where-clause instead of checking them yourself with check-statements

3. Whenever possible access the tables through primary keys. Also " select single " can be very helpful. Consider the use of the DISTINCT option in the case of many duplicate entries.

4. Ensure that you utilise internal tables wherever possible. Avoid doing a large amount of processing within a database select loop.

5. Similarly nested database selects are an absolute no-no.

•Reduce Multiple Accesses on databases

1. Avoid multiple accesses on databases.

2. Use specific fields for transferring data into the internal tables. ( use " into corresponding fields of table " flavour of the select statement ). This is especially true if less than half the available fields have to be transmitted.

3. If internal tables have many entries, a linear search through all entries is very time-consuming. Try to keep the table ordered and use binary search ( " Read table " statement with binary search ) . e.g. consider an internal table itab containing values ( 2,10,4,9,6,12,8,3).

if record with val = 3 is needed the following READ statement is used

READ TABLE ITAB WITH KEY VAL = 3.

The read operation is done sequentially here so the required record is accessed in the 8th step.

A better way to do this is :

Sorting the table using :

SORT ITAB.

READ TABLE ITAB WITH KEY VAL = 3 BINARY SEARCH.

Sorting results in :

itab = ( 2,3,4,6,8,9,10,12 )

The reqiured record is now read in the 2nd step.

Note that for best results the itab must hold large number of records.

4.Avoid doing unnecessary processing within a loop.

5.A nested database select can be avoided by using the " for all entries " flavour of the select statement. A word of caution - always ensure that the table which is used for further selections (the " for all entries in table " table contains at least one record). A failure to do this check results in all records being picked up by the select. Similarly, avoid identical where clauses for different lines of ITAB by using a sorted internal table in the SELECT … FOR ALL ENTRIES … and using the ABAP language element DELETE ADJACENT DUPLICATES prior to executing the select statement.