What are the optimization techniques?

[Former Member]

What are the optimization techniques? What is the use of those techniques and how these will use in programs

[Former Member]

Hi,

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



you can refer these links :
http://www.sapgenie.com/abap/performance.htm





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.


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.



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.

Reward is usefull

[former_member404244]

Hi,

goto tcode SE30 ,thre click on TIPS and TRICKS,u will get to know how to optimize the code..a optimized code gives u good results..

Regards,

nagaraj

[Former Member]

Check here..

http://saptechnical.com/Tutorials/ABAP/PerformanceSTDs.htm

[Former Member]

Hi,

Check the following link:

http://www.sapbrainsonline.com/ARTICLES/TECHNICAL/optimization/optimization.html

Regards,

Bhaskar