Re: compare using qry or logical

[rob@xxxxxxxxx]

There are various speed implications here.
1)  The speed of the actual generation of the OPNQRYF versus the actual 
generation of the logical file, or view.
2)  The speed of access using the file via OPNQRYF versus the speed of 
access using the logical file.
3)  The sum total of 1 & 2 done via OPNQRYF versus using a logical file.
4)  Any performance implications of leaving a logical file out there might 
have on database updates.  (I have a 1998 copy of the AS/400 Experts 
journal Volume I, Number I on my desk.  It has an article in there by Skip 
Marchesani in which he states that it is a MYTH to believe that "logical 
files on a file are resource intensive, have a negative impact on 
performance, and should only be used when absolutely necessary".  He goes 
on to state that IBM cleaned this up on V2 of OS/400 and even better in V3 
of OS/400.  Others say they have testing that disputes Skip's statements.)

If 4 doesn't prove to be a concern in your environment then item 1 drops 
out of the picture if you leave the logical file out there.  This will, in 
turn, shorten item 3.  But if you're deleting/rebuilding the logical file 
all the time you're probably losing any performance improvement.

Rob Berendt
-- 
Group Dekko Services, LLC
Dept 01.073
PO Box 2000
Dock 108
6928N 400E
Kendallville, IN 46755
http://www.dekko.com





"Dwayne Allison" <Dwayne.Allison@xxxxxxxxx> 
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10/06/2004 10:30 AM
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Subject
compare using qry or logical






We are using the following command:


OVRDBF     FILE(PA0PBR) TOFILE(PASPBR) SHARE(*YES) 
OPNQRYF    FILE((PASPBR)) QRYSLT('ARBGRP *EQ "*C*"')



Is it quicker to create a logical file with a select ARBGRP that equal *C 
only or use the above query? 

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