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From: Tom Lane <tgl@sss.pgh.pa.us>
To: cluster <skrald@amossen.dk>
Cc: Steinar H. Gunderson <sgunderson@bigfoot.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Query only slow on first run
Date: Wed, 28 Nov 2007 17:24:24 -0500
Message-ID: <24967.1196288664@sss.pgh.pa.us> (raw)
In-Reply-To: <474DDA8F.3070801@amossen.dk>
References: <fihgt1$1mmh$1@news.hub.org>
	<20071127165543.GY11978@crankycanuck.ca>
	<23999.1196184368@sss.pgh.pa.us>
	<fihn7h$2jrn$1@news.hub.org>
	<056501c83128$55d58a90$8e00a8c0@tridecap.com>
	<fii71p$oc1$1@news.hub.org>
	<20071127233833.GA24031@uio.no>
	<15029.1196209554@sss.pgh.pa.us>
	<474CBF98.6070508@amossen.dk>
	<fikia6$26ql$1@news.hub.org>
	<20071128203442.GB30600@uio.no>
	<474DDA8F.3070801@amossen.dk>

cluster <skrald@amossen.dk> writes:
> I could really use any kind of suggestion on how to improve the query in 
> order to make it scale better for large data sets The 6-7000 ms for a 
> clean run is really a showstopper. Need to get it below 70 ms somehow.

Buy a faster disk?

You're essentially asking for a random sample of data that is not
currently in memory.  You're not going to get that without some I/O.

			regards, tom lane



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