Subject: Re: Strange explain on partitioned tables
From: "Joshua D. Drake" <jd@commandprompt.com>
Reply-To: jd@commandprompt.com
To: gvfontenay@lbl.gov
Cc: pgsql-performance@postgresql.org
In-Reply-To: <4C4A11CB.6040800@lbl.gov>
References: <4C47F8C8.10005@edd.fr> <4C484874.3060609@2ndquadrant.com>
	<4C4A11CB.6040800@lbl.gov>
Content-Type: text/plain; charset="UTF-8"
Organization: Command Prompt, Inc.
Date: Fri, 23 Jul 2010 15:16:10 -0700
Message-ID: <1279923370.9866.37.camel@jd-desktop.unknown.charter.com>
Mime-Version: 1.0
Content-Transfer-Encoding: 7bit

On Fri, 2010-07-23 at 15:03 -0700, Gerald Fontenay wrote:
> > The PostgreSQL partitioning system is aimed to support perhaps a 
> > hundred inherited tables.  You can expect to get poor performance on 
> > queries if you create 1000 of them. 
> 
> Hi,
> 
> Why is that you would expect poor performance for say 1000 or more? I 
> have a ~1000 inherited tables and I don't see any significant slowdowns. 
> I only ever access a single inherited table at a time though in this 
> situation. I suppose I am using inheritance only for organization in 
> this case...

It is variable based on workload and as I recall has to do with the
planning time. As the number of children increases, so does the planning
time.

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