Subject: Re: Held idle connections vs use of a Pooler
From: "Joshua D. Drake" <jd@commandprompt.com>
Reply-To: jd@commandprompt.com
To: mark <dvlhntr@gmail.com>
Cc: pgsql-performance@postgresql.org
In-Reply-To: <AANLkTi=MBWmUSQiLJ1jq5oPZafS-8VCuUKKPR8avjbMG@mail.gmail.com>
References: <AANLkTi=MBWmUSQiLJ1jq5oPZafS-8VCuUKKPR8avjbMG@mail.gmail.com>
Content-Type: text/plain; charset="UTF-8"
Organization: Command Prompt, Inc.
Date: Tue, 14 Sep 2010 09:58:45 -0700
Message-ID: <1284483525.28610.2729.camel@jd-desktop.unknown.charter.com>
Mime-Version: 1.0
Content-Transfer-Encoding: 7bit

On Tue, 2010-09-14 at 10:10 -0600, mark wrote:
> Hello,
> 
> I am relatively new to postgres (just a few months) so apologies if
> any of you are bearing with me.
> 
> I am trying to get a rough idea of the amount of bang for the buck I
> might see if I put in a connection pooling service into the enviroment
> vs our current methodology of using persistent open connections.

Well what a pooler does is provide persisten open connections that can
be reused. What tech are you using for these persisten open connections?


> Most of the connections from the various apps hold idle connections
> until they need to execute a query once done go back to holding an
> open idle connection.  (there are ~600 open connections at any given
> time, and most of the time most are idle)

Sounds like each app is holding its own pool?


> I think from reading this list for a few weeks the answer is move to
> using connection pooling package elsewhere to better manage incoming
> connections, with a lower number to the db.

Correct, because each connection is overhead. If you have 600
connections, of which really only 20 are currently executing, that is
highly inefficient. 

A pooler would have say, 40 connections open, with 20 currently
executing and a max pool of 600.

> 
> I am told this will require some re-working of some app code as I
> understand pg-pool was tried a while back in our QA environment and
> server parts of various in-house apps/scripts/..etc started to
> experience show stopping problems.

Use pgbouncer. It is what Skype uses.

Sincerely,

Joshua D. Drake


-- 
PostgreSQL.org Major Contributor
Command Prompt, Inc: http://www.commandprompt.com/ - 509.416.6579
Consulting, Training, Support, Custom Development, Engineering
http://twitter.com/cmdpromptinc | http://identi.ca/commandprompt