Date: Wed, 1 May 2013 11:26:50 -0500
From: "ktm@rice.edu" <ktm@rice.edu>
To: Anne Rosset <arosset@collab.net>
Cc: "pgsql-performance@postgresql.org" <pgsql-performance@postgresql.org>
Subject: Re: Deterioration in performance when query executed in multi threads
Message-ID: <20130501162650.GI27807@aart.rice.edu>
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On Wed, May 01, 2013 at 04:07:55PM +0000, Anne Rosset wrote:
> Hi Ken,
> Thanks for your answer. My test is actually running with jboss 7/jdbc and the connection pool is defined  with min-pool-size =10 and max-pool-size=400.
> 
> Why would you think it is an issue with the connection pool?
> 
> Thanks,
> Anne
> 

Hi Anne,

You want to be able to run as many jobs productively at once as your hardware is
capable of supporting. Usually something starting a 2 x number of CPUs is best.
If you make several runs increasing the size of the pool each time, you will
see a maximum throughput somewhere near there and then the performance will
decrease as you add more and more connections. You can then use that sweet spot.
Your test harness should make that pretty easy to find.

Regards,
Ken


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