Re: benchmarking the query planner

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От Tom Lane
Тема Re: benchmarking the query planner
Дата
Msg-id 11419.1229030908@sss.pgh.pa.us
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Ответ на Re: benchmarking the query planner  ("Vladimir Sitnikov" <sitnikov.vladimir@gmail.com>)
Ответы Re: benchmarking the query planner  ("Vladimir Sitnikov" <sitnikov.vladimir@gmail.com>)
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"Vladimir Sitnikov" <sitnikov.vladimir@gmail.com> writes:
> One more direction could be implementing "MCV" for range of values (group
> values and interpolate in between). Consider statistics on timestamp column
> that says that for "2008-December" there are as many X rows, for
> "2008-November" as many as Y, etc.  That could be used for rather accurate
> cardinality estimation of "between" cases, while keeping number of entries
> in "MCV" list small.

I think that would likely be redundant with the histogram.
        regards, tom lane


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