RE: Is a SETLL faster than a CHAIN

Mike,

This is what I understand.

If your just checking for record existence, and the record is likely not to
be there, then use a CHAIN, since it goes directly to the record and gives
you an indication of existence. SETLL on the other hand will position the
files cursor no matter what, and that could force the process to search thru
the binary radix tree to find just the right spot between two other records.
It's the positioning of the file cursor that costs extra time. My
assumption is that if you're likely to get a hit, then a SETLL is like a
CHAIN performance wise.



-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx [mailto:rpg400-l-bounces@xxxxxxxxxxxx]
On Behalf Of Mike Cunningham
Sent: Wednesday, August 08, 2007 8:00 AM
To: RPG programming on the AS400 / iSeries
Subject: Is a SETLL faster than a CHAIN

I need to get data from a file but I know that for every 100 records I
process only 1 will have a record in the file I am going to CHAIN to. Is it
faster to first to a SETLL to see if the key exists and if it does do a
CHAIN or is just doing the CHAIN just as fast? Many years ago in the S/38
days I know the recommendation was to the SETLL then the CHAIN.