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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Hannu Krosing <hannu@2ndquadrant.com>
Cc: Robert Haas <robertmhaas@gmail.com>
Cc: Peter Hussey <peter@labkey.com>
Cc: pgsql-performance <pgsql-performance@postgresql.org>
Subject: Re: Questions on query planner, join types, and work_mem
Date: Wed, 04 Aug 2010 15:20:08 -0400
Message-ID: <24449.1280949608@sss.pgh.pa.us> (raw)
In-Reply-To: <1280948634.3735.69.camel@hvost>
References: <AANLkTikMwVZKDYLitnsK31R=VNOuTH8NtmDHDGkBR7k8@mail.gmail.com>
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	<25534.1280498632@sss.pgh.pa.us>
	<AANLkTik3oY1=F_uC843c84LxBLNdHxZaWdfjxrAtyBeu@mail.gmail.com>
	<1280819031.14579.38.camel@hvost>
	<AANLkTik6UBt2ezVFzdCM8iaUPkra_7f-Hs_AmGZgvFhh@mail.gmail.com>
	<1280944268.3735.12.camel@hvost>
	<22961.1280944836@sss.pgh.pa.us>
	<1280947287.3735.56.camel@hvost>
	<1280948634.3735.69.camel@hvost>

Hannu Krosing <hannu@2ndquadrant.com> writes:
> There was ample space for keeping the indexes in linux cache (it has 1GB
> cached currently) though the system may have decided to start writing it
> to disk, so I suspect that most of the time was spent copying random
> index pages back and forth between shared buffers and disk cache.

If you're on a platform that has oprofile, you could probably verify
that rather than just guess it ...

			regards, tom lane

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