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Architectural no-nos
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27/09/2006 17:08:10
Mike Yearwood
Toronto, Ontario, Canada
 
 
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Forum:
Visual FoxPro
Catégorie:
Codage, syntaxe et commandes
Titre:
Architectural no-nos
Versions des environnements
Visual FoxPro:
VFP 6 SP5
OS:
Windows XP
Network:
Novell 5.x
Database:
Visual FoxPro
Divers
Thread ID:
01157669
Message ID:
01157669
Vues:
83
Hi all.

I'm wondering if you'd consider this an architectural issue or something else. Please tell me what you'd call it.

I found a piece of code in an otherwise multi-user environment that builds a .IDX on a shared file. The IDX was filtered and used to access a subset of 5 million records. It took several minutes to build, but the users didn't mind that.

I tripped over this issue while debugging. I only needed to change the code to SET FILTER using existing keys instead of INDEX ON to get the same effect in seconds.

To me building an index should be a maintenance issue, not a part of regular processing.

As far as I know, VFP on the client PC reads the table on the server to produce a set of keys on the tmpfiles drive. If the tmp files are on the server the keys are sent to the server. These keys are then re-read by the client PC and sorted and rewritten to the tmpfiles drive. Then this code would begin to access the data. That's 4 trips for the key data.

Conversely, VFP on the client PC uses Rushmore to read the keys from the server into a ram-resident bitmap and this bitmap is used to access the data. That's one trip for the key data.

It seems like a multi-user system should not employ single-user architecture?
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