Performance tuning for String operation in Field routine

Question

Dear Experts,
I am writing a ABAP routine in field level  for capturing an occurence of a string.
The string may occur in anny of the values  in itab. The ITAB has around 100 thousand records and the source package 400 thousand records.
My coding goes as
LOOP AT INV_ITAB INTO INV_WA.
  IF SOURCE_FIELDS-/BIC/X_ASSIGNM  CS INV_WA-XFIELD3(7).+
     RESULT = INV_WA-PO_NO.
     EXIT.
  ELSE.
     RESULT = 'NA'.
  ENDIF.
ENDIF.
Now the coding takes more than 15 hours and still running. (It is working fine for small number of records) .
I beleive the problem is in the LOOP statement (goes around 400000*100000 times). Is it possible for me to somehow improve this code so as to decrease the load time.
Kindly help on this.
Thanks,
Rajarathnam.S

Answer 1

Hi,
I think you can use this code in your start routine instead of field level it will speed up your process.As it checks on datapacket level instead of checking records one by one.
I am just putting some logic
LOOP AT INV_ITAB INTO INV_WA.
IF  Datapackage-/BIC/X_ASSIGNM   CS INV_WA-XFIELD+3(7).
Datapackage-targetfield = INV_WA-PO_NO.
EXIT.
ELSE.
Datapackage-targetfield = 'NA'.
ENDIF.
ENDIF.
Regards,
Ravi