2 Replies Latest reply: Nov 26, 2007 12:59 PM by Siegfried Boes RSS

Select ... Endselect

Ram Chellu
Currently Being Moderated

Hi,

 

I wrote a code in start of selection. it is taking lot of time for getting output & finally going to dump. can anyone tell me how to correct my logic. don't say do like that or like this. if i change da code with out select & endselect it is not giving result. i am attaching code of which i used in my report.

 

START-OF-SELECTION.

 

SELECT * FROM A503 WHERE KAPPL = 'V'

                       AND VKORG IN S_SORG

                       AND MATNR IN S_MATNR

                       AND KSCHL = 'PR00'

                       AND DATBI GT SY-DATUM.

 

    SELECT SINGLE * FROM MARA WHERE MATNR = A503-MATNR

                         AND MATKL IN S_MATGRP.

 

    IF SY-SUBRC EQ 0.

 

    SELECT SINGLE ARKTX INTO ITAB1-ARKTX

                    FROM VBAP WHERE MATNR = A503-MATNR

                                AND MATKL IN S_MATGRP

                                AND WERKS IN S_PLANT.

 

      SELECT SINGLE * FROM KONP WHERE KNUMH = A503-KNUMH.

 

      ITAB1-MATNR = A503-MATNR.

      ITAB1-VKORG = A503-VKORG.

      ITAB1-NETPR = KONP-KBETR.

      ITAB1-UOM = KONP-KMEIN.

      ITAB1-WAERS = KONP-KONWS.

 

      SELECT * FROM MBEW WHERE MATNR = ITAB1-MATNR AND BWKEY IN S_PLANT.

        IF   MBEW-VPRSV = 'V'.

          ITAB1-COSTPR = MBEW-VERPR * MBEW-PEINH .

        ELSE.

          ITAB1-COSTPR = MBEW-STPRS * MBEW-PEINH .

        ENDIF.

        ITAB1-MARGIN = ITAB1-NETPR - ITAB1-COSTPR.

        ITAB1-WERKS = MBEW-BWKEY.

        APPEND ITAB1.

      ENDSELECT.

      CLEAR ITAB1.

    ENDIF.

  ENDSELECT.

 

SELECT SINGLE ARKTX INTO ITAB1-ARKTX

                    FROM VBAP WHERE MATNR = A503-MATNR

                                 AND MATKL IN S_MATGRP

                                 AND WERKS IN S_PLANT.

  SORT ITAB1 BY MATNR WERKS.

  DELETE ADJACENT DUPLICATES FROM ITAB1 COMPARING MATNR WERKS.

  DELETE ITAB1 WHERE MATNR EQ SPACE.

 

  PERFORM DISPLAY_DATA.

 

END-OF-SELECTION.

 

 

regards,

 

Ram

  • Re: Select ... Endselect
    Currently Being Moderated

    HI

     

    don't use SELECT and ENDSELECT it will acts like an LOOP there

     

    see these points

     

    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.

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

    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.

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

     

    Point # 2

    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 ) ).

     

    Point # 3

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

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

     

    Point # 5

    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.

     

    Point # 6

    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

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

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

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

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

     

     

    Point # 7

    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.

     

    Point # 8

    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)) .

     

    Point # 9

    APPEND LINES OF ITAB1 TO ITAB2.

    This is more optimized as compared to

    LOOP AT ITAB1 INTO WA.

      APPEND WA TO ITAB2.

    ENDLOOP.

     

    Point # 10

    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.

     

    Point # 11

    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”.

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

     

    Point # 12

    ITAB2[] = ITAB1[].

    This is much more optimized as compared to

    REFRESH ITAB2.

    LOOP AT ITAB1 INTO WA.

      APPEND WA TO ITAB2.

    ENDLOOP.

     

    Point # 13

    “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.

  • Re: Select ... Endselect
    Siegfried Boes
    Currently Being Moderated

    START-OF-SELECTION.

     

    SELECT * FROM A503 
                  WHERE KAPPL = 'V'
                  AND VKORG IN S_SORG
                  AND MATNR IN S_MATNR
                  AND KSCHL = 'PR00'
                  AND DATBI GT SY-DATUM.
    
       SELECT SINGLE * FROM MARA
                 WHERE MATNR = A503-MATNR
                 AND MATKL IN S_MATGRP.
     
       IF SY-SUBRC EQ 0.
    
           SELECT SINGLE ARKTX 
                         INTO ITAB1-ARKTX
                         FROM VBAP
                         WHERE MATNR = A503-MATNR
                         AND MATKL IN S_MATGRP
                         AND WERKS IN S_PLANT.
    
             SELECT SINGLE * FROM KONP
                          WHERE KNUMH = A503-KNUMH.
    
                ITAB1-MATNR = A503-MATNR.
                 ITAB1-VKORG = A503-VKORG.
                 ITAB1-NETPR = KONP-KBETR.
                 ITAB1-UOM = KONP-KMEIN.
                 ITAB1-WAERS = KONP-KONWS.
    
               SELECT * FROM MBEW 
                       WHERE MATNR = ITAB1-MATNR 
                       AND BWKEY IN S_PLANT.
    
                 IF MBEW-VPRSV = 'V'.
                   ITAB1-COSTPR = MBEW-VERPR * MBEW-PEINH .
                ELSE.
                   ITAB1-COSTPR = MBEW-STPRS * MBEW-PEINH .
                ENDIF.
          
                ITAB1-MARGIN = ITAB1-NETPR - ITAB1-COSTPR.
                ITAB1-WERKS = MBEW-BWKEY.
                 APPEND ITAB1.
            ENDSELECT.
            CLEAR ITAB1.
         ENDIF.
    ENDSELECT.

    <b>* hard to understand, comment the rest of the statements, and test the first part with SQL trace</b> (see

    /people/siegfried.boes/blog/2007/09/05/the-sql-trace-st05-150-quick-and-easy)

     

    <b>!!!! this is useless the table itab is created, here you can only change one record !!!</b>

    SELECT SINGLE ARKTX 
                 INTO ITAB1-ARKTX
                 FROM VBAP
                 WHERE MATNR = A503-MATNR
                 AND MATKL IN S_MATGRP
                 AND WERKS IN S_PLANT.

     

    <b>* really necessary ?</b>

    SORT ITAB1 BY MATNR WERKS.
    DELETE ADJACENT DUPLICATES FROM ITAB1
                 COMPARING MATNR WERKS.
    DELETE ITAB1 WHERE MATNR EQ SPACE.
    
    PERFORM DISPLAY_DATA.
    
    END-OF-SELECTION.

     

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