Re: Performance With Joins on Large Tables

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От Terje Elde
Тема Re: Performance With Joins on Large Tables
Дата
Msg-id 45085F3A.1040108@elde.net
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Ответ на Re: Performance With Joins on Large Tables  (Jeff Davis <pgsql@j-davis.com>)
Ответы Re: Performance With Joins on Large Tables  ("Joshua Marsh" <icub3d@gmail.com>)
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Jeff Davis wrote:
> Is it overestimating the cost of using indexes or underestimating the
> cost of a seq scan, or both? Maybe explain with the 0.1 setting will
> help?
>

If enable_seqscan is off, and cost is still set to 100000000, it could
be that it's quite simply forcibly underestimating the cost of a seqscan
in this case.

If enable_secscan was off for the mentioned plan, it'd be interesting to
see if things would be saner with seqscans enabled, and a more
reasonable random page cost.  If more 'sane' values still produce the
desired plan, it might be better for other plans etc.

Terje


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