Re: Performance Tuning Document?

Matthew Kirkwood wrote:
> Hi,
>
> I'm playing with OSDB (http://osdb.sf.net/) and trying to get
> the best numbers possible out of it.
>
> I haven't been able to find anything resembling a performance
> tuning document. Does such a thing exist?
>
> Bruce's "Hardware performance tuning" guide mentions a bunch
> of options but doesn't suggest what they should be set to. It
> also implies that, simplistically stated, "bigger is better,
> until it makes you swap", but that seems not to be always true:
>
> Under the "crossSectionTests(Mixed IR)" part of an OSDB run, a
> large number of shared_buffers causes severe slowdown on one of
> the tests -- it goes from a little over 200 seconds to nearly
> 2000. I suspect internal lock contention, or maybe it's just
> that the read() path in Linux is quicker than PG's own cache?
>
> Any tips and tricks available? Thus far, I have tried:

Gererally, I think 1/4 RAM for shared buffers is a good start, and
perhaps 2-4% for sort memory.

--
Bruce Momjian | http://candle.pha.pa.us
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