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Is it reasonable to have index on DELETED()?
Message
De
25/03/1999 03:38:19
Walter Meester
HoogkarspelPays-Bas
 
Information générale
Forum:
Visual FoxPro
Catégorie:
Base de données, Tables, Vues, Index et syntaxe SQL
Divers
Thread ID:
00196021
Message ID:
00201765
Vues:
16
cristof,

>The result is, you are right... and I'm right. *s* VFP does a full index scan first. But then it verifies that every record in that result set really matches the condition. One exception here, as I've mentioned before, is COUNT. This command only uses the index.

I'm glad we figured it out here. The conclusion might be that in this case VFP cannot optimize this kind of queries without actually accesing the table. I would have been nice as i agree that it really can significantly improve performance.

Still standing in this case is that this kind queries are not (much) faster if you omit the deleted tag.

Maybe in the future MS will implent this kind of optimization

And, YES i also did find that count is the exception here.

Thanks,

Walter,
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