Re: Free Cache Memory (Linux) and Postgresql

From: "Scott Marlowe" <scott(dot)marlowe(at)gmail(dot)com>
To: "Martijn van Oosterhout" <kleptog(at)svana(dot)org>, "Denis Gasparin" <denis(at)edistar(dot)com>, "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-general(at)postgresql(dot)org
Subject: Re: Free Cache Memory (Linux) and Postgresql
Date: 2008-09-30 23:05:41
Message-ID: dcc563d10809301605m4f40bf3cqd635bf3164fbf724@mail.gmail.com
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On Tue, Sep 30, 2008 at 4:02 PM, Martijn van Oosterhout
<kleptog(at)svana(dot)org> wrote:
> On Tue, Sep 30, 2008 at 03:51:44PM +0200, Denis Gasparin wrote:
>> It seems like postgres or the operating system (linux) is keeping in
>> cache that old data even if it has been deleted.
>
> Just remember: "free memory" is "memory you paid for and are not
> using" == "wasted memory". The OS knows damn well it's not important
> and will throw it out if necessary, but it costs nothing to keep it.

free
total used free shared buffers cached
Mem: 33031252 24901824 8129428 0 380492 21991100

shhhhh. don't tell me boss we've got 8 gig free in the db servers,
he'll want to re-purpose it.

Still 20+ Gig of cache is awfully nice.

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