Deleting logical files - was - RE: What is really the level check

Please don't bust me for copyright violations but from the November 1998,
Volume 1, Number 1 of AS/400 Experts Journal in an article by Skip
Marchesani (definitely Godlike when it comes to DB2/400):

He talked about using the Predictive Query Governor to determine which
index to build and by following it's recommendation to build a logical file
saved a 7 to 1 runtime in one example and a 12 to 1 in another.

Now for the quote:

Access paths are a good thing!

There is a myth in the AS/400 community that is no longer true.  That is:
Access paths (logical files) on a file are resource intensive, have a
negative impact on performance, and should only be used where absolutely
necessary.

This is no longer true in today's environment on the AS/400!

This myth stems from the S/38 and was the guideline that IBM was giving
customers at that time.  The Rochester development lab began to change the
algorithms for access path maintenance in Version 2 of OS/400 and finished
the task in V3R1.  Access paths (logical files) are no longer the
resource/performance hog they used to be on the S/38.


Rob Berendt

==================
"They that can give up essential liberty to obtain a little temporary
safety deserve neither liberty nor safety."
Benjamin Franklin



                    David Gibbs
                    <dgibbs@mks.com>          To:     
"'midrange-l@midrange.com'" <midrange-l@midrange.com>
                    Sent by:                  cc:
                    midrange-l-admin@mi       Fax to:
                    drange.com                Subject:     RE: What is really 
the level check


                    11/14/2001 11:23 AM
                    Please respond to
                    midrange-l






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> We have got a CL program running at the end of day, this
> program creates a
> logical file from a dds stored in a source library and calls
> a number of
> RPG programs and then it deletes the file at the end.

Why delete the logical?  Unless the overhead of maintaining the index is
extraordinary, I would recommend you just leave it out there and save the
rebuild time.

david
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