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What is the best index expression?
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À
18/04/2005 14:17:30
Information générale
Forum:
Visual FoxPro
Catégorie:
Base de données, Tables, Vues, Index et syntaxe SQL
Versions des environnements
Visual FoxPro:
VFP 8 SP1
OS:
Windows XP SP2
Divers
Thread ID:
01005870
Message ID:
01005907
Vues:
21
>I'm pretty sure that filtered index are not Rushmore optimisable. So that would make it slower. Do you have an index on SearchTB?
>
Right now I just have an index on SearchTB. I'm thinking, do I need to try to optimize the rest of the expression, e.g. have an index on empty(InsCommand) as you suggest or use the scan for as it is or do the check inside the scan...

Or use the "scan while" technique and use filtered index.

I just can not test every possible scenario, and these tests are very costly...

>>I'm thinking, could it be better to use filtered index instead.
>>
>>E.g. currently I do:
>scan for m.plError=.f. and SearchTB = m.lcSearch and not empty(InsCommand)
>May be it would be faster to set a filtered index and do seek, when scan while?
>>
>>However, as I recall, I tried similar idea (in another context, though) and it actually slowed it down.
If it's not broken, fix it until it is.


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