RE: Logical file access paths

The initial build has to read the entire file, build the key table, (Access
Path), then sort the Access Path and write it to a file.  This initial read
of the entire 10mil record file takes a while.  Adding/Deleting/Updating
record keys is done rather quickly on a record by record basis.  Don't you
just love the power of the AS400s native data base.

Christopher K. Bipes     mailto:ChrisB@Cross-Check.com
Sr. Programmer/Analyst   mailto:Chris_Bipes@Yahoo.com
CrossCheck, Inc.         http://www.cross-check.com
6119 State Farm Drive    Phone: 707 586-0551 x 1102
Rohnert Park CA  94928 Fax: 707 586-1884

If consistency is the hobgoblin of little minds, only geniuses work here.
Karen Herbelin - Readers Digest 3/2000


-----Original Message-----
From: Colin Thorpe [mailto:Colin@IBS-PUBLIC-SERVICES.CO.UK]
Sent: Wednesday, April 12, 2000 7:33 AM
To: 'RPG400-L@midrange.com'
Subject: Logical file access paths



Good morning/afternoon,

I have a question regarding access paths.

When I create a logical file over a physical file containing 10,000,000
records, it takes quite some time.

This is presumably building some kind of Matrix/lookup table?

This I can understand.

So then,
Why, when I update the key to this logical in a Do loop (so attempting to
re-read the file) , does it not have to update the matrix/lookup table
(before the re-read) and therefore take a long time to complete.

ie.
KEY     SETLL           FILE1
        DOW             *IN31=*OFF
KEY     READE   FILE1
        (CHANGE KEY)
        UPDATE  FILE1   (move this records position within the logical
order)
        ENDDO



Thanks in advance  


Colin 
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