Message-ID: <4D4ACD43.6050000@squeakycode.net>
Date: Thu, 03 Feb 2011 09:44:03 -0600
From: Andy Colson <andy@squeakycode.net>
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To: Mark Stosberg <mark@summersault.com>
CC: pgsql-performance@postgresql.org
Subject: Re: getting the most of out multi-core systems for repeated
	complex SELECT statements
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On 2/3/2011 9:08 AM, Mark Stosberg wrote:
>
> Each night we run over a 100,000 "saved searches" against PostgreSQL
> 9.0.x. These are all complex SELECTs using "cube" functions to perform a
> geo-spatial search to help people find adoptable pets at shelters.
>
> All of our machines in development in production have at least 2 cores
> in them, and I'm wondering about the best way to maximally engage all
> the processors.
>
> Now we simply run the searches in serial. I realize PostgreSQL may be
> taking advantage of the multiple cores some in this arrangement, but I'm
> seeking advice about the possibility and methods for running the
> searches in parallel.
>
> One naive I approach I considered was to use parallel cron scripts. One
> would run the "odd" searches and the other would run the "even"
> searches. This would be easy to implement, but perhaps there is a better
> way.  To those who have covered this area already, what's the best way
> to put multiple cores to use when running repeated SELECTs with PostgreSQL?
>
> Thanks!
>
>      Mark
>
>

1) I'm assuming this is all server side processing.
2) One database connection will use one core.  To use multiple cores you 
need multiple database connections.
3) If your jobs are IO bound, then running multiple jobs may hurt 
performance.

Your naive approach is the best.  Just spawn off two jobs (or three, or 
whatever).  I think its also the only method.  (If there is another 
method, I dont know what it would be)

-Andy