RE: Setll vs. chain

Carl,

Here's a third vote (Jon Paris seconded it first) for Steven's suggestion.  WAY
back when (on a /38, actually) I did some benchmarks comparing join processing,
both static via a join logical and dynamic via OPNQRYF, to RPG processing for
this kind of selection.  The join approach always won hands down, even when
OPNQRYF had to build a new index to do the job.  An interesting experiment would
be to take your existing program and just front-end it with an OPNQRYF that does
the selection via a join and uses the master file as the format file, so that
your RPG program only sees the records you want.  Every time I've tried this it
has improved processing time enormously, even if I didn't change the RPG to take
better advantage of it.

Dave Shaw
Spartan Mills
Spartanburg, SC

-----Original Message-----
From: STEVEN_J_RYAN.NDOA@notes.denso.co.jp

Have you considered a Join Logical between your Master File & your Formula
File, and using that in place of your Master File in your program?

Because the join is restricted to those records with common information
(e.g. Part number in both Master File & Formula file), you would ensure you
only read the 1000 records of your Master File that had a Formula file
equivalent.  The other 299,000+ records would be ignored by the Logical,
and so wouldn't be processed by the program.

"Carl Pitcher" <cpitcher@roadrunner.nf.net> on 10/02/2000 09:36:47

We have a report program that processes a master file of 300,000+ records
which runs ever so slow.  Each record chains to a formula file to see if a
formula exists and does some calcs. Out of the total master file, there
would be no more than 1000 successful hits on the formula file.  Before I
go ripping this code apart (and converting it to RPGIV in the process), my
expectation is that if I change the CHAIN to a SETLL and then chain on a
successful hit that it should improve the performance considerably.  Am I
wrong in assuming that SETLL will just look at the "index" which should be
in memory as opposed to CHAIN which most often requires an access to disk
to retrieve the record? TIA.
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