Will it improve performance if PACKAGE SIZE added to a select query?

Question

Hi Gurus
While doing the performance optimization I could see that in the code it is splitting the BKPF entries selected to a package of 500 and selecting from BSEG cluster table. In effect the remaining tables are also getting hit based on the no. of entries(packets) in the selected BKPF internal table.
Cant we use the package size 500  in the select statement instead of this spliting and hiting the tables in a do loop.
eg:-
      SELECT x  v z
        FROM bseg
        APPENDING TABLE lt_bseg
        PACKAGE SIZE 500
        FOR ALL ENTRIES IN lt_coep
        WHERE bukrs = lt_coep-bukrs
        AND   belnr = lt_coep-belnr_fi
        AND   gjahr = lt_coep-gjahr.
When I read the keyword documentation I saw  a note in that as " If the addition PACKAGE SIZE is specified together with FOR ALL ENTRIES, it is not passed to the database system, but is applied to the result set on the application server, after all selected rows have been read"  I did not understand the meaning of this.
So I am confused whether I can go ahead with this approach or will go along with the already used BKPF split logic and selct from BSEG and other tables in DO loop.
Can you please help me << removed >>.
Thanks & Regards,
Shinimol.
Edited by: Rob Burbank on Sep 23, 2010 9:09 AM

Answer 1

Hi,
regarding your second doubt:
> Second doubt is on the note I saw in key word documentation. " If the addition PACKAGE SIZE is specified together with FOR ALL ENTRIES, it is not passed to the database system, but is applied to the result set on the application server, after all selected rows have been read.  "  I couldn't understnd this. When I debugged the select with F5 it was selecting 500 each  till it reaches th end.
> So what does it mean, we can use this option or we should not use?
the FAE does your select in pieces and collects the result in the database interface in an inermediate buffer and
eliminates the duplicates there. AFTER this it gives you the number of rows back to your ABAP program that are specified with package size. It simply means that the package size addition has no effect on the memory consumptionfor the intermediate
buffer in the database interface.
Kind regards,
Hermann