Date: Wed, 1 May 2013 09:12:36 -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: <20130501141236.GG27807@aart.rice.edu>
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On Wed, May 01, 2013 at 02:05:06PM +0000, Anne Rosset wrote:
> Hi all,
> We are running a stress test that executes one select query with multiple threads.
> The query executes very fast (10ms). It returns 100 rows.  I see deterioration in the performance when we have multiple threads executing the query. With 100 threads, the query takes between 3s and 8s.
> 
> I suppose there is a way to tune our database. What are the parameters I should look into? (shared_buffer?, wal_buffer?)
> 
> Thanks for your help,
> Anne

Try a connection pooler like pgbouncer to keep the number of simultaneous queries
bounded to a reasonable number. You will actually get better performance.

Regards,
Ken


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