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To: pgsql-performance@postgresql.org
Subject: Re: Query only slow on first run 
In-reply-to: <20071127165543.GY11978@crankycanuck.ca> 
References: <fihgt1$1mmh$1@news.hub.org>
	<20071127165543.GY11978@crankycanuck.ca>
Comments: In-reply-to Andrew Sullivan <ajs@crankycanuck.ca>
	message dated "Tue, 27 Nov 2007 11:55:43 -0500"
Date: Tue, 27 Nov 2007 12:26:08 -0500
Message-ID: <23999.1196184368@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>
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Andrew Sullivan <ajs@crankycanuck.ca> writes:
> On Tue, Nov 27, 2007 at 05:33:36PM +0100, cluster wrote:
>> I have a query that takes about 7000 ms in average to complete the first 
>> time it runs. Subsequent runs complete in only 50 ms. That is more than 
>> a factor 100 faster! How can I make the query perform good in the first 
>> run too?

> Probably by buying much faster disk hardware.

Or buy more RAM, so that the data can stay cached.

			regards, tom lane