Re: Maximum statistics target - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Maximum statistics target
Date
Msg-id 12262.1205153194@sss.pgh.pa.us
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In response to Re: Maximum statistics target  (Peter Eisentraut <peter_e@gmx.net>)
Responses Re: Maximum statistics target
List pgsql-hackers
Peter Eisentraut <peter_e@gmx.net> writes:
> Am Freitag, 7. M�rz 2008 schrieb Tom Lane:
>> IIRC, egjoinsel is one of the weak spots, so tests involving planning of
>> joins between two tables with large MCV lists would be a good place to
>> start.

> I have run tests with joining two and three tables with 10 million rows each,
> and the planning times seem to be virtually unaffected by the statistics 
> target, for values between 10 and 800000.

It's not possible to believe that you'd not notice O(N^2) behavior for N
approaching 800000 ;-).  Perhaps your join columns were unique keys, and
thus didn't have any most-common-values?
        regards, tom lane


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