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

"Gunnar \"Nick\" Bluth" <gunnar.bluth@xxxxxxxxxxx> · Sat, 03 Nov 2012 18:09:03 +0100

    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? 

              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 ;-) 

    -- 
Gunnar "Nick" Bluth
RHCE/SCLA

Mobil   +49 172 8853339
Email: gunnar.bluth@xxxxxxxxxxx
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