Re: Now I am back, next thing. Final PGS tuning. - Mailing list pgsql-general

From Jennifer Trey
Subject Re: Now I am back, next thing. Final PGS tuning.
Date
Msg-id 863606ec0904080949k5ecc6833t37a40ec8bf0d8245@mail.gmail.com
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In response to Re: Now I am back, next thing. Final PGS tuning.  (David Wilson <david.t.wilson@gmail.com>)
List pgsql-general

Well, no.. I don't know that. But in a worst case scenario, where everything is using max, there won't be 3.5 GB for the OS. But for the OS + Postgre (combined) there will be  2.5 + 2.75 .. But it seems that there is no greater danger in the effective cache, but a good setting would be nice :) Is the effective cache only the one for the OS ? not for them combined ? 

Sincerely / Jen


On Wed, Apr 8, 2009 at 7:44 PM, David Wilson <david.t.wilson@gmail.com> wrote:
On Wed, Apr 8, 2009 at 12:24 PM, Jennifer Trey <jennifer.trey@gmail.com> wrote:

> I think I might have misunderstood the effective cache size. Its measured in
> 8kB blocks. So the old number 449697 equals 3.5 GB, which is quite much.
> Should I lower this? I had plans to use 2.75GB max. Can I put 2.75GB there?
> Should I leave it?

The effective cache size setting is merely letting postgres know how
much caching it can expect the OS to be doing. If you know that the OS
isn't going to have more than 2.75 GB available for caching DB files,
then by all means reduce it. The setting by itself doesn't affect
postgres memory usage at all, though.

--
- David T. Wilson
david.t.wilson@gmail.com

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