can anyone send tutor for performance tuning?

Former Member · ‎03-06-2007

can anyone send tutor for performance tuning?I like to chk my coding.

Former Member · ‎03-06-2007

hi

chk these links:

https://www.sdn.sap.com/irj/sdn/wiki?path=/display/home/abapPerformanceand+Tuning&

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

regards,

madhu

Former Member · ‎03-06-2007

chk these

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

www.sapdevelopment.co.uk/perform/performhome.htm

Former Member · ‎03-06-2007

For performance use below points

1 ) use binary search in read by sorting table

2) Instead of IF use case wherever req

3) remove move-corresponding from select

4) use constants whereever req instead of hardcong

In se30 transaction you can look for

Tip&TRicks button on application toolbar

apart from below conventions

Follow below steps

5) Remove * from select

6) Select field in sequence as defined in database

7) Avoid unnecessary selects

i.e check for internal table not initial

😎 Use all entries and sort table by key fields

9) Remove selects ferom loop and use binary search

10) Try to use secondary index when you don't have full key.

11) Modify internal table use transporting option

12) Avoid nested loop . Use read table and loop at itab from sy-tabix statement.

13) free intrenal table memory wnen table is not required for further processing.

Regards,

Santosh

Former Member · ‎03-06-2007

1. Unused/Dead code

Avoid leaving unused code in the program. Either comment out or delete the unused situation. Use program --> check --> extended program to check for the variables, which are not used statically.

2. Subroutine Usage

For good modularization, the decision of whether or not to execute a subroutine should be made before the subroutine is called. For example:

This is better:

IF f1 NE 0.

PERFORM sub1.

ENDIF.

FORM sub1.

...

ENDFORM.

Than this:

PERFORM sub1.

FORM sub1.

IF f1 NE 0.

...

ENDIF.

ENDFORM.

3. Usage of IF statements

When coding IF tests, nest the testing conditions so that the outer conditions are those which are most likely to fail. For logical expressions with AND , place the mostly likely false first and for the OR, place the mostly likely true first.

Example - nested IF's:

IF (least likely to be true).

IF (less likely to be true).

IF (most likely to be true).

ENDIF.

Example - IF...ELSEIF...ENDIF :

IF (most likely to be true).

ELSEIF (less likely to be true).

ELSEIF (least likely to be true).

ENDIF.

Example - AND:

IF (least likely to be true) AND

(most likely to be true).

ENDIF.

Example - OR:

IF (most likely to be true) OR

(least likely to be true).

4. CASE vs. nested Ifs

When testing fields "equal to" something, one can use either the nested IF or the CASE statement. The CASE is better for two reasons. It is easier to read and after about five nested IFs the performance of the CASE is more efficient.

5. MOVE statements

When records a and b have the exact same structure, it is more efficient to MOVE a TO b than to MOVE-CORRESPONDING a TO b.

MOVE BSEG TO *BSEG.

is better than

MOVE-CORRESPONDING BSEG TO *BSEG.

6. SELECT and SELECT SINGLE

When using the SELECT statement, study the key and always provide as much of the left-most part of the key as possible. If the entire key can be qualified, code a SELECT SINGLE not just a SELECT. If you are only interested in the first row or there is only one row to be returned, using SELECT SINGLE can increase performance by up to three times.

7. Small internal tables vs. complete internal tables

In general it is better to minimize the number of fields declared in an internal table. While it may be convenient to declare an internal table using the LIKE command, in most cases, programs will not use all fields in the SAP standard table.

For example:

Instead of this:

data: t_mara like mara occurs 0 with header line.

Use this:

data: begin of t_mara occurs 0,

matnr like mara-matnr,

...

end of t_mara.

8. Row-level processing and SELECT SINGLE

Similar to the processing of a SELECT-ENDSELECT loop, when calling multiple SELECT-SINGLE commands on a non-buffered table (check Data Dictionary -> Technical Info), you should do the following to improve performance:

o Use the SELECT into <itab> to buffer the necessary rows in an internal table, then

o sort the rows by the key fields, then

o use a READ TABLE WITH KEY ... BINARY SEARCH in place of the SELECT SINGLE command. Note that this only make sense when the table you are buffering is not too large (this decision must be made on a case by case basis).

9. READing single records of internal tables

When reading a single record in an internal table, the READ TABLE WITH KEY is not a direct READ. This means that if the data is not sorted according to the key, the system must sequentially read the table. Therefore, you should:

o SORT the table

o use READ TABLE WITH KEY BINARY SEARCH for better performance.

10. SORTing internal tables

When SORTing internal tables, specify the fields to SORTed.

SORT ITAB BY FLD1 FLD2.

is more efficient than

SORT ITAB.

11. Number of entries in an internal table

To find out how many entries are in an internal table use DESCRIBE.

DESCRIBE TABLE ITAB LINES CNTLNS.

is more efficient than

LOOP AT ITAB.

CNTLNS = CNTLNS + 1.

ENDLOOP.

12. Performance diagnosis

To diagnose performance problems, it is recommended to use the SAP transaction SE30, ABAP/4 Runtime Analysis. The utility allows statistical analysis of transactions and programs.

13. Nested SELECTs versus table views

Since releASE 4.0, OPEN SQL allows both inner and outer table joins. A nested SELECT loop may be used to accomplish the same concept. However, the performance of nested SELECT loops is very poor in comparison to a join. Hence, to improve performance by a factor of 25x and reduce network load, you should either create a view in the data dictionary then use this view to select data, or code the select using a join.

14. If nested SELECTs must be used

As mentioned previously, performance can be dramatically improved by using views instead of nested SELECTs, however, if this is not possible, then the following example of using an internal table in a nested SELECT can also improve performance by a factor of 5x:

Use this:

form select_good.

data: t_vbak like vbak occurs 0 with header line.

data: t_vbap like vbap occurs 0 with header line.

select * from vbak into table t_vbak up to 200 rows.

select * from vbap

for all entries in t_vbak

where vbeln = t_vbak-vbeln.

...

endselect.

endform.

Instead of this:

form select_bad.

select * from vbak up to 200 rows.

select * from vbap where vbeln = vbak-vbeln.

...

endselect.

endform.

Although using "SELECT...FOR ALL ENTRIES IN..." is generally very fast, you should be aware of the three pitfalls of using it:

Firstly, SAP automatically removes any duplicates from the rest of the retrieved records. Therefore, if you wish to ensure that no qualifying records are discarded, the field list of the inner SELECT must be designed to ensure the retrieved records will contain no duplicates (normally, this would mean including in the list of retrieved fields all of those fields that comprise that table's primary key).

Secondly, if you were able to code "SELECT ... FROM <database table> FOR ALL ENTRIES IN TABLE <itab>" and the internal table <itab> is empty, then all rows from <database table> will be retrieved.

Thirdly, if the internal table supplying the selection criteria (i.e. internal table <itab> in the example "...FOR ALL ENTRIES IN TABLE <itab> ") contains a large number of entries, performance degradation may occur.

15. SELECT * versus SELECTing individual fields

In general, use a SELECT statement specifying a list of fields instead of a SELECT * to reduce network traffic and improve performance. For tables with only a few fields the improvements may be minor, but many SAP tables contain more than 50 fields when the program needs only a few. In the latter case, the performace gains can be substantial. For example:

Use:

select vbeln auart vbtyp from table vbak

into (vbak-vbeln, vbak-auart, vbak-vbtyp)

where ...

Instead of using:

select * from vbak where ...

16. Avoid unnecessary statements

There are a few cases where one command is better than two. For example:

Use:

append <tab_wa> to <tab>.

Instead of:

<tab> = <tab_wa>.

append <tab> (modify <tab>).

And also, use:

if not <tab>[] is initial.

Instead of:

describe table <tab> lines <line_counter>.

if <line_counter> > 0.

17. Copying or appending internal tables

Use this:

<tab2>[] = <tab1>[]. (if <tab2> is empty)

Instead of this:

loop at <tab1>.

append <tab1> to <tab2>.

endloop.

However, if <tab2> is not empty and should not be overwritten, then use:

append lines of <tab1> [from index1] [to index2] to <tab2>.

P.S : Please reward if you find this useful..

Former Member · ‎03-06-2007

http://www.sap-img.com/abap/abap-fine-tuning.htm

http://www.allsaplinks.com/performanc_tuning.html

website.www.esnips.com

Here are some performance TIPS

LOOP AT with WHERE clause

Working with internal tables

For all entries

Tools for performance tuning

Using table buffering

LOOP AT with WHERE clause

If you use a LOOP AT statement with a WHERE clause, the table whole will be read through

and not only the entriers that satifies the WHERE clause. This can lead to performance

problems when a very large internal table is read many times with a WHERE clause.

The solution is to sort the table on the keyfields, use a READ statment to find

the first entry that satifies the key. Then you can start the loop here, and check for

changes in the keyfield to exit the loop.

Do not

loop at gi_mseg into g_mseg

where matnr = p_matnr and

werks = p_werks and

lgort = p_lgort and

sobkz = space,

endloop.

Instead use:

Sort internal table with entries from MSEG

sort gi_mseg by matnr werks lgort.

Find index of first entry that satifies the where clause

data:

l_tabix_from like sy-tabix.

read table gi_mseg with key matnr = p_matnr

werks = p_werks

lgort = p_lgort binary search

into g_mseg.

check sy-tabix > 0.

move sy-tabix to l_tabix_from.

Loop over the table from l_tabix_from, check for changes in keyfields, and

if necessary check other fields.

loop at gi_mseg into g_mseg from l_tabix_from.

if g_mseg-matnr <> p_matnr or

g_mseg-werks <> p_werks or

g_mseg-lgort <> p_lgort.

Stop loop

exit.

endif.

Check other fields

check g_mseg-sobkz = space.

..... do something ......

endloop.

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.

Some steps that might make FOR ALL ENTRIES more efficient:

- Removing duplicates from the 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.

Tools for performance tuning

The runtime analysis (SE30)

SQL Trace (ST05)

Tips and Tricks tool

The performance 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 staments the buffer will be bypassed. These staments are:

Select DISTINCT

ORDER BY / GROUP BY / HAVING clause

Any WHERE clasuse that contains a subquery or IS NULL expression

JOIN

A SELECT... FOR UPDATE

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

REgards,

Kishore