Performance optimization in Select query

Question

Hi All,
Please suggest good performance practice for the below code.
SELECT * FROM BKPF WHERE BUKRS IN SO_BUKRS
                        AND BELNR IN SO_BELNR
                        AND GJAHR IN SO_GJAHR
                        AND BLART IN SO_BLART
                        AND BUDAT IN SO_BUDAT
                        AND USNAM IN SO_USNAM.
     CLEAR BSEG.
     SELECT * FROM BSEG WHERE BUKRS EQ BKPF-BUKRS
                          AND BELNR EQ BKPF-BELNR
                          AND GJAHR EQ BKPF-GJAHR
                          AND KOART EQ 'K'.
       SELECT SINGLE * FROM LFA1 WHERE LIFNR EQ BSEG-LIFNR
                                   AND KTOKK IN SO_KTOKK.
       CHECK SY-SUBRC EQ 0.
       MOVE-CORRESPONDING BKPF TO ITAB2.
       MOVE BSEG-LIFNR TO ITAB2-LIFNR.
       APPEND ITAB2.
     ENDSELECT.
     PERFORM CHECK_FOR_REVERSAL.
   ENDSELECT.
Thanks
Sonal

Answer 1

declare internal table for BKPF, BSEG & LFA1 separately.
instead of using Select & End select, use for all entries.
SELECT * FROM BKPF into table itab1 WHERE BUKRS IN SO_BUKRS
AND BELNR IN SO_BELNR
AND GJAHR IN SO_GJAHR
AND BLART IN SO_BLART
AND BUDAT IN SO_BUDAT
AND USNAM IN SO_USNAM.
if not itab1[] is initial.
  sort bkpf by belnr.
SELECT * FROM BSEG into table itab2
for all entries in itab1
WHERE BUKRS EQ itab1-BUKRS
AND BELNR EQ itab1-BELNR
AND GJAHR EQ itab1-GJAHR
AND KOART EQ 'K'.
if not itab2[] is initial.
  sort itab2 by lifnr
   SELECT SINGLE * FROM LFA1 into table itab3
   for all entries in itab2
   WHERE LIFNR EQ itab2-LIFNR
AND KTOKK IN SO_KTOKK.
endif.
endif.
endif.
sort itab1 by belnr.
sort itab2 by belnr.
sort itab3 by lifnr.
loop at itab1.
move-corresponding itab1 to itfinal.
  loop at itab2 where belnr = itab1-belnr.
    move-corresponding itab2 to itfinal.
    read itab3 with key lifnr = itab2-lifnr.
    if sy-subrc = 0.
      move-corresponding itab3 to itfinal.
    endif.
  endloop.
append itfinal.
clear itfinal.
endloop.