EXCEPT vs. UPDATE (was Re: rpg400-l-digest V1 #241)

["Dan Bale" <dbale@xxxxxxxxxxx>]

When I write an app from scratch, my rule is: NEVER modify a database field
unless you intend to update it in the database, and don't modify it until just
before the UPDATE.  This is done by using a subroutine that does nothing but
update the database fields and then does the UPDATE.  This way, I am assured
that I can use UPDATE without updating a field that was not intended to be
updated.

- Dan Bale

From: Joel Fritz <JFritz@sharperimage.com>
Subject: RE: rpg400-l-digest V1 #241

<SNIP>
Point 2:  I didn't always do much exception output to files.  For a batch
job that runs several hours, exception output can give you a performance
boost that makes a difference provided you don't have the option of unkeyed
sequential I/O.  For programs that run in a few minutes, or interactive
programs I rarely use it.
<SNIP>
> From: Pete [mailto:prmoore@mail.globalnet.co.uk]
<SNIP>
> > 2.  Exception output has some legitimate uses.  If you're
> updating a few
> > fields in a large record format in a batch process on a
> large file, you can
> > get a performance boost by using exception output.
> Obviously the best
> > performance comes from using sequential input and output to
> a new file that
> > replaces the original (using write), but you don't always
> have that luxury.
> I'm not persuaded by most machine-efficiency arguments.
> Anyway are you saying that the compiler generates less code
> via O-specs
> than field moves?
<SNIP>





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