Index scan question

[Don Coleman]

> -----Original Message-----
> From: filepro-list-bounces+dcoleman=dgcreact.com at lists.celestial.com
> [mailto:filepro-list-bounces+dcoleman=dgcreact.com at lists.celestial.com] On
> Behalf Of Kenneth Brody
> Sent: Friday, July 25, 2008 11:06 AM
> To: filepro-list at lists.celestial.com
> Subject: Re: Index scan question
> 
> Quoting Don Coleman (Fri, 25 Jul 2008 10:44:45 -0400):
> 
> [...]
> > Built an index on a YESNO field where for a *report export process where
> > I only want to select 11 (YESNO) eq "" (blank)
> >
> > There are 465,000 records in this file.   This export is to run every 3
> > minutes so I would expect a maximum of 2000-3000 records (peak periods)
> to
> > be selected for each 3 minute interval scan.  The number exported could
> drop
> > to several hundred records or less during non-peak times.  However when
> I
> > run the *report export process the app. still reads through 25,000-
> 30,000
> > records.  While that's not the entire file and some time has been saved,
> I
> > don't understand why it is not only reading the exact records to be
> > selected.  There is no select process involved and no "ne" statement in
> my
> > selection set.  The selection set is simply:
> >
> > Group	Field		Description		REL	Value
> > 	11		Exported (Y/N)	eq
> [...]
> 
> That doesn't make sense.  If index scan is turned off, it would read all
> 465,000 records in the file.  If index scan is being used, filePro would
> only read the records where field 11 is blank.
> 
> Is there any chance that there are really only about 30,000 used records
> in the file, and the rest are deleted?
> 
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Ken:

Yes, this file is archived each night, moving 80-90% of the records
contained to an archive qualifier.  What you suggest now makes sense.  As
the day goes on, the number of records being read is increasing, now over
40,000.  I tried adding another field to the selection set, 
Field #1(8,*) gt "" (blank) but it still is reading all the records.  I also
confirmed PFIXS=ON is in the environment.  What can I add to only read the
records where field #11 is equal to ""(blank)?  This seems so simple yet ...


Don Coleman
Donald G. Coleman, Consultant
402 Andrew Circle
Indiana, PA 15701
dcoleman at dgcreact.com
(724) 349-6302