From: Scott Marlowe <scott.marlowe@gmail.com>
To: Jessica Richard <rjessil@yahoo.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: how to estimate shared_buffers...
Date: Sat, 12 Jul 2008 07:05:59 -0600
Message-ID: <dcc563d10807120605j7dbfe12ek4dc6b7cfdfdee0a5@mail.gmail.com> (raw)
In-Reply-To: <93721.43246.qm@web56401.mail.re3.yahoo.com>
References: <93721.43246.qm@web56401.mail.re3.yahoo.com>
On Sat, Jul 12, 2008 at 5:30 AM, Jessica Richard <rjessil@yahoo.com> wrote:
> On a running production machine, we have 900M configured on a 16G-memory
> Linux host. The db size for all dbs combined is about 50G. There are many
> transactions going on all the times (deletes, inserts, updates). We do not
> have a testing environment that has the same setup and the same amount of
> workload. I want to evaluate on the production host if this 900M is enough.
> If not, we still have room to go up a little bit to speed up all Postgres
> activities. I don't know enough about the SA side. I just would imagine, if
> something like "top" command or other tools can measure how much total
> memory Postgres is actually using (against the configured 900M shared
> buffers), and if Postgres is using almost 900M all the time, I would take
> this as an indication that the shared_buffers can go up for another 100M...
>
> What is the best way to tell how much memory Postgres (all Postgres related
> things) is actually using?
If you've got a 50G data set, then postgresql is most likely using
whatever memory you give it for shared buffers. top should show that
easily.
I'd say start at 25% ~ 4G (this is a 64 bit machine, right?). That
leaves plenty of memory for the OS to cache data, and for postgresql
to allocate work_mem type stuff from.
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: scott.marlowe@gmail.com, rjessil@yahoo.com
Subject: Re: how to estimate shared_buffers...
In-Reply-To: <dcc563d10807120605j7dbfe12ek4dc6b7cfdfdee0a5@mail.gmail.com>
* 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