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Message Posted: Thu, 22 Jan 2004 @ 22:34:15 GMT

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Subj:   Re: Misunderstanding of join index
From:   Victor Sokovin

  Does anybody can explain why a SELECT with a COUNT(FIELD_1) or COUNT (DISTINCT FIELD_1) statement does not use the JI? I understand why we can't create a JI with COUNT DISTINCT but I can't figure out for the SELECT statement. In my mind, the JI have the information to return the COUNT information.  

I assume you are referring to the same example as in the original posting? If so, COUNT(FIELD_1) cannot be calculated on the JI because the aggregation on FIELD_1 had already been done and the original level of granularity is lost. COUNT(DISTINCT FIELD_1) could potentially be calculated on the JI. Perhaps you could experiment with statistics?


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