Message-ID: <50B8B954.7060807@optionshouse.com>
Date: Fri, 30 Nov 2012 07:49:08 -0600
From: Shaun Thomas <sthomas@optionshouse.com>
Reply-To: <sthomas@optionshouse.com>
Organization: Peak6
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To: =?ISO-8859-1?Q?Niels_Kristian_Schj=F8dt?= <nielskristian@autouncle.com>
CC: Kevin Grittner <kgrittn@mail.com>, Willem Leenen
	<willem_leenen@hotmail.com>, <pgsql-performance@postgresql.org>
Subject: Re: Optimize update query
References: <20121130120359.69330@gmx.com>
	<F4B46CCF-BB27-428C-B4A6-A6C71D171650@autouncle.com>
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On 11/30/2012 07:31 AM, Niels Kristian Schj=F8dt wrote:

> In theory what difference should it make to the performance, to have
> a pool in front of the database, that all my workers and web servers
> connect to instead of connecting directly? Where is the performance
> gain coming from in that situation?

If you have several more connections than you have processors, the
database does a *lot* more context switching, and among other things,
that drastically reduces PG performance. On a testbed, I can get over
150k transactions per second on PG 9.1 with a 1-1 relationship between
CPU and client. Increase that to a few hundred, and my TPS drops down to
30k. Simply having the clients there kills performance.


--
Shaun Thomas
OptionsHouse | 141 W. Jackson Blvd. | Suite 500 | Chicago IL, 60604
312-444-8534
sthomas@optionshouse.com

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