To: "Jignesh K. Shah" <J.K.Shah@Sun.COM>
Cc: Scott Carey <scott@richrelevance.com>,  Tom Lane <tgl@sss.pgh.pa.us>,
	Kevin Grittner <Kevin.Grittner@wicourts.gov>,
	"pgsql-performance\@postgresql.org" <pgsql-performance@postgresql.org>
Subject: Re: Proposal of tunable fix for scalability of 8.4
In-Reply-To: <49BA53CF.4020702@sun.com> (Jignesh K. Shah's message of "Fri\,
	13 Mar 2009 08\:38\:39 -0400")
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References: <C5DEE151.33BA%scott@richrelevance.com> <49BA53CF.4020702@sun.com>
From: Gregory Stark <stark@enterprisedb.com>
Organization: EnterpriseDB
Date: Fri, 13 Mar 2009 13:05:36 +0000
Message-ID: <871vt1609r.fsf@oxford.xeocode.com>
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"Jignesh K. Shah" <J.K.Shah@Sun.COM> writes:

> Scott Carey wrote:
>> On 3/12/09 11:37 AM, "Jignesh K. Shah" <J.K.Shah@Sun.COM> wrote:
>>
>> In general, I suggest that it is useful to run tests with a few different
>> types of pacing. Zero delay pacing will not have realistic number of
>> connections, but will expose bottlenecks that are universal, and less
>> controversial
>
> I think I have done that before so I can do that again by running the users at
> 0 think time which will represent a "Connection pool" which is highly utilized"
> and test how big the connection pool can be before the throughput tanks.. This
> can be useful for App Servers which sets up connections pools of their own
> talking with PostgreSQL.

Keep in mind when you do this that it's not interesting to test a number of
connections much larger than the number of processors you have. Once the
system reaches 100% cpu usage it would be a misconfigured connection pooler
that kept more than that number of connections open.

-- 
  Gregory Stark
  EnterpriseDB          http://www.enterprisedb.com
  Ask me about EnterpriseDB's PostGIS support!