RE: PF with lotsa LFs

["Joe Pluta" <joepluta@xxxxxxxxxxxxxxxxx>]

> From: alan shore
>
> Wow
> when I was first introduced to the AS/400 (I know - now i-Series)
> and the idea of Logicals, I was told that there should be at
> least one very important question asked -
> How often is this Logical required?
> If the logical is required 1, 2 , 3 , 4 times a year etc.,
> contmplate OPNQRYF instead.
> Just a suggestion

Alan makes a good point.  The overhead associated with a logical file has to
do with the fact that the indexes need to be modified every time a record is
added, updated or deleted.  With 100+ logicals, this can be a lot of
activity, particularly if the file is updated often.  For a fiarly static
file, like a table of state codes, that's not an issue, but for transaction
files, balance files and the like, it can be a lot of overhead.

There's also a middle ground - MAINT(*DLY).  On the CRTLF command you can
specify MAINT(*DLY) which means that the logical is rebuilt when it is used.
Actually, it's not entirely rebuilt, just updated to reflect changes since
the last time it was used.

This way, for a program that isn't called often, you can create the logical
file but you won't incur the overhead until the program is actually called.
There will be additional overhead when the program is started, to do the
rebuild, but that's the tradeoff - overall system performance vs. a longer
run time for selected programs.

There are many options, and the one you take really depends on your business
requirements.

Joe