Subject: Re: Need help in performance tuning.
From: Hannu Krosing <hannu@2ndquadrant.com>
To: Kevin Grittner <Kevin.Grittner@wicourts.gov>
Cc: Scott Marlowe <scott.marlowe@gmail.com>,
	Samuel Gendler <sgendler@ideasculptor.com>,
	pgsql-performance@postgresql.org, Tom Lane <tgl@sss.pgh.pa.us>
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Date: Wed, 14 Jul 2010 17:54:51 +0300
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On Wed, 2010-07-14 at 08:58 -0500, Kevin Grittner wrote:
> Scott Marlowe <scott.marlowe@gmail.com> wrote:
> > Hannu Krosing <hannu@2ndquadrant.com> wrote:
> >> One example where you need a separate connection pool is pooling
> >> really large number of connections, which you may want to do on
> >> another host than the database itself is running.
> > 
> > Definitely.  Often it's best placed on the individual webservers
> > that are making requests, each running its own pool.
>  
> Each running its own pool?  You've just made a case for an
> admissions policy based on active database transactions or active
> queries (or both) on the server having a benefit when used with this
> pooling arrangement.  This collection of pools can't know when the
> CPUs have enough to keep them busy and adding more will degrade
> performance.

I guess this setup is for OLTP load (read "lots of short transactions
with low timeout limits"), where you can just open 2-5 connections per
CPU for mostly-in-memory database, maybe a little more when disk
accesses are involved. If you have more, then they just wait a few
milliseconds, if you have less, you don't have anything else to run
anyway.


-- 
Hannu Krosing   http://www.2ndQuadrant.com
PostgreSQL Scalability and Availability 
   Services, Consulting and Training