Message-Id: <4E69BA830200002500040FD2@gw.wicourts.gov>
Date: Fri, 09 Sep 2011 07:04:35 -0500
From: "Kevin Grittner" <Kevin.Grittner@wicourts.gov>
To: <greg@2ndQuadrant.com>,<aa@devshock.com>,
	<pgsql-performance@postgresql.org>
Subject: Re: how delete/insert/update affects select
	 performace?
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"Anibal David Acosta"  wrote:
 
>> The general guidelines for Windows servers such as
>> http://wiki.postgresql.org/wiki/Tuning_Your_PostgreSQL_Server
>> recommend a fairly small setting for the shared_buffers parameters
>> on Windows--no more than 512MB.
 
> Even if I have a server with 16GB of ram, I must set the
> shared_buffer to 512MB on windows?
> 
> In the wiki page they talk about 1/4 of ram, in my case that
> represent a shared_buffer = 4GB, that is incorrect?
 
There's an effective maximum, depending on the platform.  On Linux
that seems to be somewhere in the 8GB to 10GB.  On Windows it is much
less.
 
> If I can't configure more than 512MB of shared_buffer all other RAM
> is unnecessary?
 
The RAM not used for other purposes is used by the OS for caching. 
PostgreSQL goes through that cache, so the extra memory will be used;
it's a question of what balance between PostgreSQL buffers and OS
cache gives the best performance.
 
-Kevin