RE: Record blocking optimization

["Joel Fritz" <JFritz@xxxxxxxxxxxxxxxx>]

The records will be read in keyed sequence.  As long as you use read to
get the record and don't use any random i/o you'll get the benefit of
blocking.  When I did mailing list processing I did a fair amount of
this kind of thing except we always used unkeyed files that were sorted
by key.  The benefit from setting the block size depends on the size of
the files.  With modern hardware it may not do that much for you.  If
the files are huge--tens of millions of records--it might be worth it.
OTOH, using sequential i/o vs. keyed i/o regardles of block size will
perk things up. 

The seqonly parm on ovrdbf refers to sequential i/o vs. keyed i/o.  

-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx
[mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of Alan C
Sent: Monday, March 14, 2005 8:06 PM
To: RPG programming on the AS400 / iSeries
Subject: Re: Record blocking optimization

Hi Tony.

I believe the records will still be input in keyed order, but someone
with specific memories could answer more definitively.

That said, on first listen, this sounds like it might lend itself to the
old RPG cycle, which still works in RPG-IV, if the idea is to optimize.

It's hard to beat the cycle, though I'm sure buffering optimization
would get close.  Using primary and secondary, the compiler sets up the
optimum block size.

- Alan


>

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