From: Kenneth Marshall <ktm@rice.edu>
To: Peter Schuller <peter.schuller@infidyne.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: shared_buffers in 8.3 w/ lots of RAM on dedicated PG machine
Date: Fri, 15 Feb 2008 07:37:34 -0600
Message-ID: <20080215133734.GU12156@it.is.rice.edu> (raw)
In-Reply-To: <20080215123528.GA16532@hyperion.scode.org>
References: <20080215123528.GA16532@hyperion.scode.org>
On Fri, Feb 15, 2008 at 01:35:29PM +0100, Peter Schuller wrote:
> Hello,
>
> my impression has been that in the past, there has been a general
> semi-consensus that upping shared_buffers to use the majority of RAM
> has not generally been recommended, with reliance on the buffer cache
> instead being the recommendation.
>
> Given the changes that have gone into 8.3, in particular with regards
> to minimizing the impact of large sequential scans, would it be
> correct to say that given that
>
> - enough memory is left for other PG bits (sort mems and whatnot else)
> - only PG is running on the machine
> - you're on 64 bit so do not run into address space issues
> - the database working set is larger than RAM
>
> it would be generally advisable to pump up shared_buffers pretty much
> as far as possible instead of relying on the buffer cache?
>
> --
> / Peter Schuller
>
> PGP userID: 0xE9758B7D or 'Peter Schuller <peter.schuller@infidyne.com>'
> Key retrieval: Send an E-Mail to getpgpkey@scode.org
> E-Mail: peter.schuller@infidyne.com Web: http://www.scode.org
>
Peter,
PostgreSQL still depends on the OS for file access and caching. I
think that the current recommendation is to have up to 25% of your
RAM in the shared buffer cache.
Ken
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-performance@postgresql.org
Cc: ktm@rice.edu, peter.schuller@infidyne.com
Subject: Re: shared_buffers in 8.3 w/ lots of RAM on dedicated PG machine
In-Reply-To: <20080215133734.GU12156@it.is.rice.edu>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox