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West Wind Web Connection
Dan,
SNIP
>I think this clearly demonstrates what you are saying. If you have one condition that has a small number of index keys and one that has a large number of index keys, you are better off having just an index on the set that returns the small number.
>
>As you have stated though, the data is changing all the time. Is the penalty that I am getting now about .1 to .2 worth constantly monitoring the data basically doing what Oracle or SQL Server would do - Kind of a crude statistics. I don't know.
>
Since this seems to be somewhat critical to you, it may well be worth "monitoring" intermittently. But you could probably devise a program to do this for you during off-hours, checking the current data content for known regularly used search criteria and evaluate if action is needed.
Of course you would also have to store the search criteria actually used in some table to ascertain which field(s) occur most often.
One thing I encourage you to do... the UT "Documents" section of this (VFP) forum has a document for "VFP 8 Wishes" and it is regularly reviewed/forwarded to MS' VFP Team. You could add 'cost-based optimization' (or whatever you would prefer as an enhancement) to the document.
good luck,
JimN
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