Re: RT3.4 query needed a lot more tuning with 9.2 than it did with 8.1

От: Tom Lane
Тема: Re: RT3.4 query needed a lot more tuning with 9.2 than it did with 8.1
Дата: ,
Msg-id: 11475.1368476046@sss.pgh.pa.us
(см: обсуждение, исходный текст)
Ответ на: Re: RT3.4 query needed a lot more tuning with 9.2 than it did with 8.1  (Robert Haas)
Ответы: Re: RT3.4 query needed a lot more tuning with 9.2 than it did with 8.1  (Robert Haas)
Список: pgsql-performance


Robert Haas <> writes:
> The planner is estimating this the outer side of this nested loop will
> produce 33 rows and that the inner side will produce 1.  One would
> assume that the row estimate for the join product couldn't be more
> than 33 * 1 = 33 rows, but the planner is estimating 62335 rows, which
> seems like nonsense.

You know, of course, that the join size estimate isn't arrived at that
way.  Still, this point does make it seem more like a planner bug and
less like bad input stats.  It would be nice to see a self-contained
example ...

            regards, tom lane



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