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

On 3 November 2012 12:09, Gunnar "Nick" Bluth <gunnar(dot)bluth(at)pro-open(dot)de>wrote:

> Am 03.11.2012 16:20, schrieb Petr Praus:
>
>
> Your CPUs are indeed pretty oldschool. FSB based, IIRC, not NUMA. A
>> process migration would be even more expensive there.
>>
>>
> Ok, I've actually looked these up now... at the time these were current, I
> was in the lucky situation to only deal with Opterons. And actually, with
> these CPUs it is pretty possible that Scott Marlowe's hint (check
> vm.zone_reclaim_mode) was pointing in the right direction. Did you check
> that?
>

I did check that, it's zero. I responded to his message, but my messages to
the mailing list are getting delayed by ~24 hours because somebody has to
always bless them.

>
>
> Yes, same behaviour. I let the shared_buffers be the default (which
>> is 8MB). With work_mem 1MB the query runs fast, with 96MB it runs slow
>> (same times as before). It really seems that the culprit is work_mem.
>>
>
>
> Well, I'm pretty sure that having more work_mem is a good thing (tm)
> normally ;-)
>

Well, that's what I always thought too! :-)

> --
> Gunnar "Nick" Bluth
> RHCE/SCLA
>
> Mobil +49 172 8853339
> Email: gunnar(dot)bluth(at)pro-open(dot)de
> __________________________________________________________________________
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>
>