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Former Member

Performance turing

Dear all ,

The below query takes more than 1 minute to select vgbel , vbeln from VBRP table. After sorting and deleting adjacent duplicate it_delv[] should have only one record. Even it takes more than 1 minute for selection.

Sort it_del[] by vgbel vbeln

delete adjacenn duplicates comparing bt vgbel vbeln

IF NOT it_delv[] IS INITIAL.

SELECT

vbrp~vgbel

vbrp~vbeln

INTO CORRESPONDING FIELDS OF TABLE it_inv

FROM vbrp JOIN vbrk

ON vbrpvbeln = vbrkvbeln

FOR ALL ENTRIES IN it_delv

WHERE vbrp~vgbel = it_delv-vgbel

AND vbrk~vbtyp = 'U'.

ENDIF.

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6 Answers

  • author's profile photo Former Member
    Former Member
    Posted on Nov 30, 2007 at 07:29 AM

    Hi

    your useing joins thats why its taking so much time

    what happend you know when you use JOINS , the data base connection for that tables will be there for long time up to the program execution result in which it will increase the load on database

    so better to use FOR ALL ENTRIES it will retrive data from database at once and no further connection with data base

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  • author's profile photo Former Member
    Former Member
    Posted on Nov 30, 2007 at 07:29 AM

    Ways of Performance Tuning

    1. Selection Criteria

    2. Select Statements

    • Select Queries

    • SQL Interface

    • Aggregate Functions

    • For all Entries

    Select Over more than one internal table

    Selection Criteria

    1. Restrict the data to the selection criteria itself, rather than filtering it out using the ABAP code using CHECK statement.

    2. Select with selection list.

    SELECT * FROM SBOOK INTO SBOOK_WA.

    CHECK: SBOOK_WA-CARRID = 'LH' AND

    SBOOK_WA-CONNID = '0400'.

    ENDSELECT.

    The above code can be much more optimized by the code written below which avoids CHECK, selects with selection list

    SELECT CARRID CONNID FLDATE BOOKID FROM SBOOK INTO TABLE T_SBOOK

    WHERE SBOOK_WA-CARRID = 'LH' AND

    SBOOK_WA-CONNID = '0400'.

    Select Statements Select Queries

    1. Avoid nested selects

    SELECT * FROM EKKO INTO EKKO_WA.

    SELECT * FROM EKAN INTO EKAN_WA

    WHERE EBELN = EKKO_WA-EBELN.

    ENDSELECT.

    ENDSELECT.

    The above code can be much more optimized by the code written below.

    SELECT PF1 PF2 FF3 FF4 INTO TABLE ITAB

    FROM EKKO AS P INNER JOIN EKAN AS F

    ON PEBELN = FEBELN.

    Note: A simple SELECT loop is a single database access whose result is passed to the ABAP program line by line. Nested SELECT loops mean that the number of accesses in the inner loop is multiplied by the number of accesses in the outer loop. One should therefore use nested SELECT loops only if the selection in the outer loop contains very few lines or the outer loop is a SELECT SINGLE statement.

    2. Select all the records in a single shot using into table clause of select statement rather than to use Append statements.

    SELECT * FROM SBOOK INTO SBOOK_WA.

    CHECK: SBOOK_WA-CARRID = 'LH' AND

    SBOOK_WA-CONNID = '0400'.

    ENDSELECT.

    The above code can be much more optimized by the code written below which avoids CHECK, selects with selection list and puts the data in one shot using into table

    SELECT CARRID CONNID FLDATE BOOKID FROM SBOOK INTO TABLE T_SBOOK

    WHERE SBOOK_WA-CARRID = 'LH' AND

    SBOOK_WA-CONNID = '0400'.

    3. When a base table has multiple indices, the where clause should be in the order of the index, either a primary or a secondary index.

    To choose an index, the optimizer checks the field names specified in the where clause and then uses an index that has the same order of the fields. In certain scenarios, it is advisable to check whether a new index can speed up the performance of a program. This will come handy in programs that access data from the finance tables.

    4. For testing existence, use Select.. Up to 1 rows statement instead of a Select-Endselect-loop with an Exit.

    SELECT * FROM SBOOK INTO SBOOK_WA

    UP TO 1 ROWS

    WHERE CARRID = 'LH'.

    ENDSELECT.

    The above code is more optimized as compared to the code mentioned below for testing existence of a record.

    SELECT * FROM SBOOK INTO SBOOK_WA

    WHERE CARRID = 'LH'.

    EXIT.

    ENDSELECT.

    5. Use Select Single if all primary key fields are supplied in the Where condition .

    If all primary key fields are supplied in the Where conditions you can even use Select Single.

    Select Single requires one communication with the database system, whereas Select-Endselect needs two.

    Select Statements SQL Interface

    1. Use column updates instead of single-row updates

    to update your database tables.

    SELECT * FROM SFLIGHT INTO SFLIGHT_WA.

    SFLIGHT_WA-SEATSOCC =

    SFLIGHT_WA-SEATSOCC - 1.

    UPDATE SFLIGHT FROM SFLIGHT_WA.

    ENDSELECT.

    The above mentioned code can be more optimized by using the following code

    UPDATE SFLIGHT

    SET SEATSOCC = SEATSOCC - 1.

    2. For all frequently used Select statements, try to use an index.

    SELECT * FROM SBOOK CLIENT SPECIFIED INTO SBOOK_WA

    WHERE CARRID = 'LH'

    AND CONNID = '0400'.

    ENDSELECT.

    The above mentioned code can be more optimized by using the following code

    SELECT * FROM SBOOK CLIENT SPECIFIED INTO SBOOK_WA

    WHERE MANDT IN ( SELECT MANDT FROM T000 )

    AND CARRID = 'LH'

    AND CONNID = '0400'.

    ENDSELECT.

    3. Using buffered tables improves the performance considerably.

    Bypassing the buffer increases the network considerably

    SELECT SINGLE * FROM T100 INTO T100_WA

    BYPASSING BUFFER

    WHERE SPRSL = 'D'

    AND ARBGB = '00'

    AND MSGNR = '999'.

    The above mentioned code can be more optimized by using the following code

    SELECT SINGLE * FROM T100 INTO T100_WA

    WHERE SPRSL = 'D'

    AND ARBGB = '00'

    AND MSGNR = '999'.

    Select Statements Aggregate Functions

    • If you want to find the maximum, minimum, sum and average value or the count of a database column, use a select list with aggregate functions instead of computing the aggregates yourself.

    Some of the Aggregate functions allowed in SAP are MAX, MIN, AVG, SUM, COUNT, COUNT( * )

    Consider the following extract.

    Maxno = 0.

    Select * from zflight where airln = ‘LF’ and cntry = ‘IN’.

    Check zflight-fligh > maxno.

    Maxno = zflight-fligh.

    Endselect.

    The above mentioned code can be much more optimized by using the following code.

    Select max( fligh ) from zflight into maxno where airln = ‘LF’ and cntry = ‘IN’.

    Select Statements 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)

    Points to be must considered FOR ALL ENTRIES

    • Check that data is present in the driver table

    • Sorting the driver table

    • Removing duplicates from the driver table

    Consider the following piece of extract

    Loop at int_cntry.

    Select single * from zfligh into int_fligh

    where cntry = int_cntry-cntry.

    Append int_fligh.

    Endloop.

    The above mentioned can be more optimized by using the following code.

    Sort int_cntry by cntry.

    Delete adjacent duplicates from int_cntry.

    If NOT int_cntry[] is INITIAL.

    Select * from zfligh appending table int_fligh

    For all entries in int_cntry

    Where cntry = int_cntry-cntry.

    Endif.

    Select Statements Select Over more than one Internal table

    1. Its better to use a views instead of nested Select statements.

    SELECT * FROM DD01L INTO DD01L_WA

    WHERE DOMNAME LIKE 'CHAR%'

    AND AS4LOCAL = 'A'.

    SELECT SINGLE * FROM DD01T INTO DD01T_WA

    WHERE DOMNAME = DD01L_WA-DOMNAME

    AND AS4LOCAL = 'A'

    AND AS4VERS = DD01L_WA-AS4VERS

    AND DDLANGUAGE = SY-LANGU.

    ENDSELECT.

    The above code can be more optimized by extracting all the data from view DD01V_WA

    SELECT * FROM DD01V INTO DD01V_WA

    WHERE DOMNAME LIKE 'CHAR%'

    AND DDLANGUAGE = SY-LANGU.

    ENDSELECT

    2. To read data from several logically connected tables use a join instead of nested Select statements. Joins are preferred only if all the primary key are available in WHERE clause for the tables that are joined. If the primary keys are not provided in join the Joining of tables itself takes time.

    SELECT * FROM EKKO INTO EKKO_WA.

    SELECT * FROM EKAN INTO EKAN_WA

    WHERE EBELN = EKKO_WA-EBELN.

    ENDSELECT.

    ENDSELECT.

    The above code can be much more optimized by the code written below.

    SELECT PF1 PF2 FF3 FF4 INTO TABLE ITAB

    FROM EKKO AS P INNER JOIN EKAN AS F

    ON PEBELN = FEBELN.

    3. Instead of using nested Select loops it is often better to use subqueries.

    SELECT * FROM SPFLI

    INTO TABLE T_SPFLI

    WHERE CITYFROM = 'FRANKFURT'

    AND CITYTO = 'NEW YORK'.

    SELECT * FROM SFLIGHT AS F

    INTO SFLIGHT_WA

    FOR ALL ENTRIES IN T_SPFLI

    WHERE SEATSOCC < F~SEATSMAX

    AND CARRID = T_SPFLI-CARRID

    AND CONNID = T_SPFLI-CONNID

    AND FLDATE BETWEEN '19990101' AND '19990331'.

    ENDSELECT.

    The above mentioned code can be even more optimized by using subqueries instead of for all entries.

    SELECT * FROM SFLIGHT AS F INTO SFLIGHT_WA

    WHERE SEATSOCC < F~SEATSMAX

    AND EXISTS ( SELECT * FROM SPFLI

    WHERE CARRID = F~CARRID

    AND CONNID = F~CONNID

    AND CITYFROM = 'FRANKFURT'

    AND CITYTO = 'NEW YORK' )

    AND FLDATE BETWEEN '19990101' AND '19990331'.

    ENDSELECT.

    1. Table operations should be done using explicit work areas rather than via header lines.

    READ TABLE ITAB INTO WA WITH KEY K = 'X‘ BINARY SEARCH.

    IS MUCH FASTER THAN USING

    READ TABLE ITAB INTO WA WITH KEY K = 'X'.

    If TAB has n entries, linear search runs in O( n ) time, whereas binary search takes only O( log2( n ) ).

    2. Always try to use binary search instead of linear search. But don’t forget to sort your internal table before that.

    READ TABLE ITAB INTO WA WITH KEY K = 'X'. IS FASTER THAN USING

    READ TABLE ITAB INTO WA WITH KEY (NAME) = 'X'.

    3. A dynamic key access is slower than a static one, since the key specification must be evaluated at runtime.

    4. A binary search using secondary index takes considerably less time.

    5. LOOP ... WHERE is faster than LOOP/CHECK because LOOP ... WHERE evaluates the specified condition internally.

    LOOP AT ITAB INTO WA WHERE K = 'X'.

    " ...

    ENDLOOP.

    The above code is much faster than using

    LOOP AT ITAB INTO WA.

    CHECK WA-K = 'X'.

    " ...

    ENDLOOP.

    6. Modifying selected components using “ MODIFY itab …TRANSPORTING f1 f2.. “ accelerates the task of updating a line of an internal table.

    WA-DATE = SY-DATUM.

    MODIFY ITAB FROM WA INDEX 1 TRANSPORTING DATE.

    The above code is more optimized as compared to

    WA-DATE = SY-DATUM.

    MODIFY ITAB FROM WA INDEX 1.

    7. Accessing the table entries directly in a "LOOP ... ASSIGNING ..." accelerates the task of updating a set of lines of an internal table considerably

    Modifying selected components only makes the program faster as compared to Modifying all lines completely.

    e.g,

    LOOP AT ITAB ASSIGNING <WA>.

    I = SY-TABIX MOD 2.

    IF I = 0.

    <WA>-FLAG = 'X'.

    ENDIF.

    ENDLOOP.

    The above code works faster as compared to

    LOOP AT ITAB INTO WA.

    I = SY-TABIX MOD 2.

    IF I = 0.

    WA-FLAG = 'X'.

    MODIFY ITAB FROM WA.

    ENDIF.

    ENDLOOP.

    8. If collect semantics is required, it is always better to use to COLLECT rather than READ BINARY and then ADD.

    LOOP AT ITAB1 INTO WA1.

    READ TABLE ITAB2 INTO WA2 WITH KEY K = WA1-K BINARY SEARCH.

    IF SY-SUBRC = 0.

    ADD: WA1-VAL1 TO WA2-VAL1,

    WA1-VAL2 TO WA2-VAL2.

    MODIFY ITAB2 FROM WA2 INDEX SY-TABIX TRANSPORTING VAL1 VAL2.

    ELSE.

    INSERT WA1 INTO ITAB2 INDEX SY-TABIX.

    ENDIF.

    ENDLOOP.

    The above code uses BINARY SEARCH for collect semantics. READ BINARY runs in O( log2(n) ) time. The above piece of code can be more optimized by

    LOOP AT ITAB1 INTO WA.

    COLLECT WA INTO ITAB2.

    ENDLOOP.

    SORT ITAB2 BY K.

    COLLECT, however, uses a hash algorithm and is therefore independent

    of the number of entries (i.e. O(1)) .

    9. "APPEND LINES OF itab1 TO itab2" accelerates the task of appending a table to another table considerably as compared to “ LOOP-APPEND-ENDLOOP.”

    APPEND LINES OF ITAB1 TO ITAB2.

    This is more optimized as compared to

    LOOP AT ITAB1 INTO WA.

    APPEND WA TO ITAB2.

    ENDLOOP.

    10. “DELETE ADJACENT DUPLICATES“ accelerates the task of deleting duplicate entries considerably as compared to “ READ-LOOP-DELETE-ENDLOOP”.

    DELETE ADJACENT DUPLICATES FROM ITAB COMPARING K.

    This is much more optimized as compared to

    READ TABLE ITAB INDEX 1 INTO PREV_LINE.

    LOOP AT ITAB FROM 2 INTO WA.

    IF WA = PREV_LINE.

    DELETE ITAB.

    ELSE.

    PREV_LINE = WA.

    ENDIF.

    ENDLOOP.

    11. "DELETE itab FROM ... TO ..." accelerates the task of deleting a sequence of lines considerably as compared to “ DO -DELETE-ENDDO”.

    DELETE ITAB FROM 450 TO 550.

    This is much more optimized as compared to

    DO 101 TIMES.

    DELETE ITAB INDEX 450.

    ENDDO.

    12. Copying internal tables by using “ITAB2[ ] = ITAB1[ ]” as compared to “LOOP-APPEND-ENDLOOP”.

    ITAB2[] = ITAB1[].

    This is much more optimized as compared to

    REFRESH ITAB2.

    LOOP AT ITAB1 INTO WA.

    APPEND WA TO ITAB2.

    ENDLOOP.

    13. Specify the sort key as restrictively as possible to run the program faster.

    “SORT ITAB BY K.” makes the program runs faster as compared to “SORT ITAB.”

    Internal Tables contd…

    Hashed and Sorted tables

    1. For single read access hashed tables are more optimized as compared to sorted tables.

    2. For partial sequential access sorted tables are more optimized as compared to hashed tables

    Hashed And Sorted Tables

    Point # 1

    Consider the following example where HTAB is a hashed table and STAB is a sorted table

    DO 250 TIMES.

    N = 4 * SY-INDEX.

    READ TABLE HTAB INTO WA WITH TABLE KEY K = N.

    IF SY-SUBRC = 0.

    " ...

    ENDIF.

    ENDDO.

    This runs faster for single read access as compared to the following same code for sorted table

    DO 250 TIMES.

    N = 4 * SY-INDEX.

    READ TABLE STAB INTO WA WITH TABLE KEY K = N.

    IF SY-SUBRC = 0.

    " ...

    ENDIF.

    ENDDO.

    Point # 2

    Similarly for Partial Sequential access the STAB runs faster as compared to HTAB

    LOOP AT STAB INTO WA WHERE K = SUBKEY.

    " ...

    ENDLOOP.

    This runs faster as compared to

    LOOP AT HTAB INTO WA WHERE K = SUBKEY.

    " ...

    ENDLOOP.

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  • author's profile photo Former Member
    Former Member
    Posted on Nov 30, 2007 at 07:36 AM

    Mahesh,

    Remove into corresponding, specify te required fields in select query and make a internal table according to that.

    Try to use all the key fields in where clause in the same order as they appear in DB Table.

    Use FOR ALL ENTRIES if possible, as there are only 2 table join is also fine.

    Regards,

    Satish

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  • author's profile photo Former Member
    Former Member
    Posted on Nov 30, 2007 at 08:44 AM

    U shouldnt use comparing bt vgbel vbeln .

    it will take more time,

    Then dont use both join and for all entries same time use any one.

    defnetly it will reduce ur burden.

    regards

    jay

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  • author's profile photo Former Member
    Former Member
    Posted on Nov 30, 2007 at 08:54 AM

    Mahesh ,

    once again this is jay,

    select distinct vgbel vbeln from vbrk as a join vbrp as p on avbeln eq bvbeln

    into table itab1 where vgbel eq it_delv-vgbel.

    Before this declare an internal table with fields vgbel and vbeln.

    and pass these values to that int table and to the needed variable or other table.

    even delete adjacent duplicates not needed.

    This will reduce the load on ur prog.

    Regards

    jay

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  • author's profile photo Former Member
    Former Member
    Posted on Nov 30, 2007 at 09:49 PM

    Your problem is that you do not use any indexes in your SELECT. I think you can do better by first using your document number (I assume it's a delevery) and going to table VBFA (Sales document flow) to get the subsequent (billing) document. and use that to go against VBRP and VBRK.

    Don't worry about JOINS and FOR ALL ENTRIES. JOINS are a bit better for performance, but the gains are not generally huge.

    Rob

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