Performance Tuning

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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 stament 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 s
A SELECT... FOR UPDATE
If you wnat to explicitly bypass the bufer, use the BYPASS BUFFER addition to the SELECR 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 datbase server will usually be the bottleneck, so sometimes it is better to move thje sort from the datsbase 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 stament 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 datbase server sort it.


Avoid ther 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 duplciate rows.

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