Re: Order by (for 15 rows) adds 30 seconds to query time

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От Tom Lane
Тема Re: Order by (for 15 rows) adds 30 seconds to query time
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Msg-id 22914.1259790512@sss.pgh.pa.us
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Ответ на Re: Order by (for 15 rows) adds 30 seconds to query time  ("Kevin Grittner" <Kevin.Grittner@wicourts.gov>)
Ответы Re: Order by (for 15 rows) adds 30 seconds to query time  ("Kevin Grittner" <Kevin.Grittner@wicourts.gov>)
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"Kevin Grittner" <Kevin.Grittner@wicourts.gov> writes:
> Estimates extracted from the problem plan:

>   Nested Loop Left Join  (rows=806903677108)
>     ->  Nested Loop Left Join  (rows=203176856)
>           ->  Nested Loop Left Join  (rows=51160)
>                 ->  Nested Loop Left Join  (rows=28)
>                 ->  Append  (rows=4)
>           ->  Append  (rows=2)
>     ->  Append  (rows=2)

That does look weird.  Do we have a self-contained test case?

I wouldn't necessarily expect the join rowcount to be exactly the
product of the input rowcounts, but it shouldn't be that far off,
I should think.

            regards, tom lane

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