Re: shared_buffers and shmmax what are the max recommended values? - Mailing list pgsql-general

From Anton Melser
Subject Re: shared_buffers and shmmax what are the max recommended values?
Date
Msg-id 92d3a4950803070827x53b70153u5b10ce15f6760a19@mail.gmail.com
Whole thread Raw
In response to Re: shared_buffers and shmmax what are the max recommended values?  (Greg Smith <gsmith@gregsmith.com>)
List pgsql-general
That's crystal. Thanks for your advice!
Cheers
Anton

On 07/03/2008, Greg Smith <gsmith@gregsmith.com> wrote:
> On Fri, 7 Mar 2008, Anton Melser wrote:
>
>
> > There is actually quite a bit of write (at least the dump is increasing
>  > far more than what is being added manually by content writers... and I'm
>  > not even certain where it is coming from but that is another story!)
>
>
> If you look at pg_stat_user_tables regularly that should give you an idea
>  what's being added/updated/deleted.
>
>
>  > yes checkpoint_segments is at the default... if I increase to 10 or so
>  > will that be better?
>
>
> There will be less checkpoints, which may be better for you.  But each
>  checkpoint could be doing more work, so they will be more disruptive,
>  which can be worse.  It's not a parameter you can increase and that will
>  always be an improvement.
>
>  Normally people doing write-heavy work set that into the 30-100 range.
>  You will use more disk space for the WAL files used by the server, and
>  recovery from a crash will take longer as well.  The default of 3 keeps
>  WAL files at a total of about 112MB; increasing to 10 raises that to
>  336MB, and at 30 you can expect to have 1GB of WAL files around on the
>  primary server.
>
>
>  > btw, we have a warm standby via wal copies if that makes a difference...
>
>
> Changing checkpoint_segments doesn't alter how often WAL files are moved
>  over, but it will increase how many of them you need to keep around on the
>  secondary in order to rebuild the server after a crash.  You should be
>  careful making changes here until you understand how all that fits
>  together.
>
>
>  --
>  * Greg Smith gsmith@gregsmith.com http://www.gregsmith.com Baltimore, MD
>


--
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