Re: Re: Increasing work_mem and shared_buffers on Postgres 9.2 significantly slows down queries

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От Petr Praus
Тема Re: Re: Increasing work_mem and shared_buffers on Postgres 9.2 significantly slows down queries
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Msg-id CACezXZ9OL7BmngxwcYzGouw-Jz-0AkBQCQLGwOUvvPiHbebiyA@mail.gmail.com
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Ответ на Re: Re: Increasing work_mem and shared_buffers on Postgres 9.2 significantly slows down queries  ("Gunnar \"Nick\" Bluth" <gunnar.bluth@pro-open.de>)
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On 6 November 2012 14:17, Gunnar "Nick" Bluth <gunnar.bluth@pro-open.de> wrote:
Am 06.11.2012 21:08, schrieb Petr Praus: See the change in the plan between 10MB and 12MB, directly at top level? That narrows the thing down quite a bit.

Though I wonder why this didn't show in the original plans...

Yes, the 2,4 and 10 are the same, the only difference is number of buckets. But with 12, it makes completely different choices, it decides to make sequential scans and hash right joins instead of merge joins. And those sequential scans take a loong time. Could this be caused by some missing indices perhaps?

The original plans I posted at the start are the same as the 12MB plan, I'm not sure why is that, I really hope I didn't make some sort of mistake there.

Thanks for your help by the way! :-)
 


--
Gunnar "Nick" Bluth
RHCE/SCLA

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Email: gunnar.bluth@pro-open.de
__________________________________________________________________________
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they are choosing Windows over UNIX.  What part of that message aren't you
getting? - Tom Payne


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