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From: Ron Mayer <rm_pg@cheapcomplexdevices.com>
To: Scott Carey <scott@richrelevance.com>
Cc: Christiaan Willemsen <cwillemsen@technocon.com>
Cc: Joshua D. Drake <jd@commandprompt.com>
Cc: Merlin Moncure <mmoncure@gmail.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: How to setup disk spindles for best performance
Date: Thu, 21 Aug 2008 12:14:47 -0700
Message-ID: <48ADBEA7.5060107@cheapcomplexdevices.com> (raw)
In-Reply-To: <a1ec7d000808210753w3a954e5g1d4f4325775d8eca@mail.gmail.com>
References: <972BDF1A-B4ED-46EC-B416-0CDF15A0439A@technocon.com>
	<b42b73150808201849t3577d65eq76e7484d8519af51@mail.gmail.com>
	<331B8FD1-7460-4B97-BD2C-03D8381E1C4D@technocon.com>
	<48AD022E.7090400@commandprompt.com>
	<48AD288B.8030902@technocon.com>
	<a1ec7d000808210753w3a954e5g1d4f4325775d8eca@mail.gmail.com>

Scott Carey wrote:
> For reads, if your shared_buffers is large enough, your heavily used 
> indexes won't likely go to disk much at all.

ISTM this would happen regardless of your shared_buffers setting.
If you have enough memory the OS should cache the frequently used
pages regardless of shared_buffers; and if you don't have enough
memory it won't.

> ... splitting up data and indexes ...

FWIW, I've had a system where moving pgsql_tmp to different disks
helped more than moving indexes.



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