Re: performance loading a subfile

[Chris Bipes <chris.bipes@xxxxxxxxxxxxxxx>]

If "the selection is worth it" statement is true, create a LF that has an index 
on the selection.  Then use a query tool, opnqryf or imbedded SQL to perform 
the selection.  With the index available, the query should run quickly and your 
program will only see the qualified records.  Subfile will load with just 10 
reads.  Let the query manager work for YOU!

IMHO
Christopher K. Bipes             Mailto:chrisb@cross-check.com
Senior Programmer/Analyst  Http://www.cross-check.com
CrossCheck, Inc.                  707 586-0551 x 1102
6119 State Farm Drive          707 586-1884  FAX
Rohnert Park, CA  94928

----- Original Message ----- 
From: <booth@martinvt.com>
To: <rpg400-l@midrange.com>
Sent: Tuesday, September 12, 2000 5:55 PM
Subject: performance loading a subfile


Here's the scenario:

A large file is being loaded a page at a time, 10 records per page.  There 
is a filter set for one of the fields.

With no filter set the subfile loads quickly and happily.  However if the 
user chooses to filter out  99.5% of the records then loading the 10 
records may take thousands of reads to find 10 that pass.  In this case 
the performance is dreadful.  The selection is worth it so we wish to do 
it but is there some way to display records as we go, or choose a line 
before the whole subfile page is full? 

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