Re: [PATCHES] Better default_statistics_target

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От Tom Lane
Тема Re: [PATCHES] Better default_statistics_target
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Msg-id 24107.1201881016@sss.pgh.pa.us
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Ответ на Re: [PATCHES] Better default_statistics_target  ("Kevin Grittner" <Kevin.Grittner@wicourts.gov>)
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"Kevin Grittner" <Kevin.Grittner@wicourts.gov> writes:
> On Thu, Jan 31, 2008 at 10:19 PM, in message
> <200801312319.59723.xzilla@users.sourceforge.net>, Robert Treat
> <xzilla@users.sourceforge.net> wrote: 
>> Bad plans from boosting to 100 or less? Or something much higher? 
> I boosted on a large number of columns based on domains.  County
> number columns (present in most tables) were set to 80.  Some
> columns were set all the way to 1000.  When performance tanked, we
> didn't have time to experiment, so we just backed it all out.
> Perhaps I could do some more controlled testing soon against 8.3,
> to narrow it down and confirm the current status of the issue.  I
> do seem to recall that simple queries weren't suffering, it was
> those which joined many tables which had multiple indexes.

That fits with the idea that eqjoinsel() is a main culprit.
        regards, tom lane


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