Selection in other way to improve performence

Question

Any body can suggest me how i can write the first selection in another way with the same logic.
it_date TYPE STANDARD TABLE OF rsdsselopt,
SELECT bukrs belnr gjahr cpudt cputm aedat awkey
FROM bkpf INTO TABLE it_bkpf
WHERE cpudt IN it_date.
help me to write same select in another form which can suggest for performence.
Tks.

Answer 1

Hi,
I have played with your select trying to improve it. Using bukrs like '%' suggested by Diego did not improved performance in my case. But using standard index with fields bukrs, cpudt, bstat is good idea. If you do not want to create a new secondary index and you can not limit your selection for a concrete BUKRS, the best approach I have found is doing the select this way:
data: it_date TYPE STANDARD TABLE OF rsdsselopt,
         it_t001 TYPE STANDARD TABLE OF t001,
         wa_t001 TYPE t001.
SELECT * FROM t001 INTO TABLE it_t001.
LOOP AT it_t001 INTO wa_t001.
SELECT bukrs belnr gjahr cpudt cputm aedat awkey
FROM bkpf APPENDING TABLE it_bkpf
WHERE bukrs EQ wa_t001-bukrs
      AND cpudt IN it_date.
ENDLOOP.
For it_date use only such values which can be transformed to EQ, IN and BETWEEN if possible, so do not use excluding select-options, instead of operand < try to put some lower boundary and use BETWEEN instead.
Disadvantage of this approach is that select is performed more than once. I was trying to eliminate this disadvantage doiing it this way:
data: it_date TYPE STANDARD TABLE OF rsdsselopt,
         it_t001 TYPE STANDARD TABLE OF t001.
SELECT * FROM t001 INTO TABLE it_t001.
LOOP AT it_t001 INTO wa_t001.
SELECT bukrs belnr gjahr cpudt cputm aedat awkey
FROM bkpf INTO TABLE it_bkpf
FOR ALL ENTRIES IN it_t001
WHERE bukrs EQ it_t001-bukrs
      AND cpudt IN it_date.
ENDLOOP.
But when I looked at a execution plan for this select, although FOR ALL ENTRIES was translated using IN operator, no index was used by selection. So, this one did not bring any improvement. But it can be individual and it depends on system, because FOR ALL ENTRIES can be implemented in different way depends on database system, version and system parameters. Maybe you can try to take also this FOR ALL ENTRIES approach and improve it by changing parameters rsdb/prefer_join, rsdb/prefer_union_all, rsdb/prefer_in_itab_opt via hints.
But I would recommend to use the first approach I have used if it is sufficient improvement.
You should become more familiar with transaction ST05 and using SQL trace to anlayse database operations.
Hope it helps.
Regards,
Adrian