Re: Slow Query- Bad Row Estimate - Mailing list pgsql-performance

From Tom Lane
Subject Re: Slow Query- Bad Row Estimate
Date
Msg-id 9343.1288387050@sss.pgh.pa.us
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In response to Slow Query- Bad Row Estimate  ("Ozer, Pam" <pozer@automotive.com>)
Responses Re: Slow Query- Bad Row Estimate
List pgsql-performance
"Ozer, Pam" <pozer@automotive.com> writes:
> Unfortunately I have not received a response on this question.  Is more
> information needed?  Does anyone have any ideas why the estimates may be
> bad?  Or what I might be able to do to speed this up?

The most likely explanation for the bad rowcount estimates is that there
is correlation between the regionid/countyid/cityid columns, only the
planner doesn't know it.  Can you reformulate that data representation
at all, or at least avoid depending on it as a join key?

            regards, tom lane

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