Re: Possible to improve query plan?

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От Tom Lane
Тема Re: Possible to improve query plan?
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Msg-id 9658.1295890414@sss.pgh.pa.us
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Ответ на Re: Possible to improve query plan?  ("Kevin Grittner" <Kevin.Grittner@wicourts.gov>)
Ответы Re: Possible to improve query plan?  ("Kevin Grittner" <Kevin.Grittner@wicourts.gov>)
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"Kevin Grittner" <Kevin.Grittner@wicourts.gov> writes:
> Robert Haas <robertmhaas@gmail.com> wrote:
>> But isn't 13.5 seconds awfully slow to scan 149557 rows?  The sort
>> is sorting 23960kB.  Dividing that by 149557 rows gives ~169
>> bytes/per row

> You're right.  I would expect 9 ms as per tuple as a worst case if
> it doesn't need to go to TOAST data.  Caching, multiple rows per
> page, or adjacent pages should all tend to bring it down from there.
> How does it get to 90 ms per row with rows that narrow?

Um, that looks like 90 usec per row, not msec.

            regards, tom lane

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