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
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
The Minus
Some steps that might make FOR ALL ENTRIES more efficient:
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.
The plus:
The minus:
The plus
The minus
SELECT * FROM SBOOK.
CHECK: SBOOK-CARRID = 'LH' AND
SBOOK-CONNID = '0400'.
ENDSELECT.
SELECT * FROM SBOOK
WHERE CARRID = 'LH' AND
CONNID = '0400'.
ENDSELECT.
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 * 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 * 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.
REFRESH X006. SELECT * FROM T006 INTO X006. APPEND X006. ENDSELECT SELECT * FROM T006 INTO TABLE X006.
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
LOOP AT TAB. CHECK TAB-K = KVAL. " ... ENDLOOP. LOOP AT TAB WHERE K = KVAL. " ... ENDLOOP.
REFRESH TAB_DEST. LOOP AT TAB_SRC INTO TAB_DEST. APPEND TAB_DEST. ENDLOOP. TAB_DEST[] = TAB_SRC[].
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.
DO 101 TIMES. DELETE TAB_DEST INDEX 450. ENDDO. DELETE TAB_DEST FROM 450 TO 550.
READ TABLE TAB WITH KEY K = 'X'. READ TABLE TAB WITH KEY K = 'X' BINARY SEARCH.
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.
LOOP AT TAB. TAB-DATE = SY-DATUM. MODIFY TAB. ENDLOOP. WA-DATE = SY-DATUM. LOOP AT TAB. MODIFY TAB FROM WA TRANSPORTING DATE. ENDLOOP.
LOOP AT TAB_SRC. APPEND TAB_SRC TO TAB_DEST. ENDLOOP APPEND LINES OF TAB_SRC TO TAB_DEST.
LOOP AT TAB_DEST WHERE K = KVAL. DELETE TAB_DEST. ENDLOOP DELETE TAB_DEST WHERE K = KVAL.
The runtime analysis (SE30)
SQL Trace (ST05)
Tips and Tricks tool
The performance database
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:
If you wnat to explicitly bypass the bufer, use the BYPASS BUFFER addition to the SELECR clause.
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.
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.