How to improve JOINs ?

Question

Hi
Is always usefull to 'separate' a JOIN for improve the performance ?
That is, instead to use a Join accesing two tables, make first one Select accesing the first table, and then make a second select using a FOR ALL ENTRIES for the first Internal Table.
How can we improve something like this ???
SELECT vbak~vbeln   
           vbak~vbtyp   
           vbak~vkorg  
           vbak~vtweg   
           vbak~spart   
           vbak~kunnr   
           vbak~auart   
           vbak~audat   
      FROM vbak
      INNER JOIN vbpa
      ON vbakvbeln EQ vbpavbeln AND
         vbpa~posnr EQ c_poszero
      INNER JOIN vbkd
      ON vbakvbeln EQ vbkdvbeln AND
         vbkd~posnr EQ c_poszero
      INNER JOIN vbuk
      ON vbakvbeln EQ vbukvbeln
      INTO TABLE i_vbak
      WHERE vbak~auart IN r_auart
        AND vbak~vkorg IN s_vkorg
        AND vbak~spart IN s_spart
        AND vbak~audat IN s_odate
        AND vbak~waerk IN s_waerk
        AND vbak~vkbur IN s_vkbur
        AND vbak~vsbed IN s_vsbed
        AND vbkd~ktgrd IN s_ktgrd
        AND vbkd~bzirk IN s_bzirk
        AND vbuk~gbstk IN s_gbstk
        AND vbak~vbeln IN s_vbeln
        AND vbpa~kunnr IN s_kunnr
        AND vbpa~parvw EQ c_parvzs
        AND vbak~vbtyp IN r_vbtyp.
The only obligatory field is s_vkorg.
Regards
Frank

Answer 1

Hi,
first try which table is taking more time
to do this keep two tables at a time and comment others
put break point then check performance. go on doing the same
remove the table which is taking the more time and go for for all entries
Thanks
Shiva