• Subject: Re: Query Optimizer
  • From: John P Carr <jpcarr@xxxxxxxxxxxx>
  • Date: Tue, 9 Nov 1999 11:38:06 -0500

>Hmmm. I don't know. I'd estimate 60-80%. I was doing some testing on a 
>rather complex view, looking for messages that would indicate which indexes

>were needed. What are the implications of selecting a large vs a small 
>percentage of the data?
>Pete Hall

I believe that if the optimizer thinks that >20% of the result set contains
the 
requested data,  It will not use the index it will use Sequential/Skip
Sequential.


After that it might build an index for the rest of the needs(order by,
Having, Joining, etc)
It might build a Bitmap and do further refinements via XOR/AND type things
on the bitmap.
John Carr





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