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From: Greg Smith <greg@2ndquadrant.com>
To: Kevin Grittner <Kevin.Grittner@wicourts.gov>
Cc: David Kerr <dmk@mr-paradox.net>
Cc: pgsql-performance@postgresql.org, Tom Lane <tgl@sss.pgh.pa.us>
Subject: Re: pgbench could not send data to client: Broken		 pipe
Date: Thu, 09 Sep 2010 14:07:22 -0400
Message-ID: <4C89225A.1080504@2ndquadrant.com> (raw)
In-Reply-To: <4C88D1F1020000250003544F@gw.wicourts.gov>
References: <20100908174629.GD40339@mr-paradox.net>
	<8037.1283973026@sss.pgh.pa.us>
	<4C87E3A6.8060800@2ndquadrant.com>
	<20100908195654.GB49941@mr-paradox.net>
	<9771.1283978128@sss.pgh.pa.us>
	<20100908204443.GG49941@mr-paradox.net>
	<4C87B22802000025000353B7@gw.wicourts.gov>
	<20100908212056.GI49941@mr-paradox.net>
	<4C87BF0502000025000353BE@gw.wicourts.gov>
	<20100908220011.GA59539@mr-paradox.net>
	<4C87C77C02000025000353D2@gw.wicourts.gov>
	<4C8905C5.1060709@2ndquadrant.com>
	<4C88D1F1020000250003544F@gw.wicourts.gov>

Kevin Grittner wrote:
> In my experience you can expect the response time benefit of
> reducing the size of your connection pool to match available
> resources to be more noticeable than the throughput improvements. 
> This directly contradicts many people's intuition, revealing the
> downside of "gut feel".
>   

This is why I focused on showing there won't actually be a significant 
throughput reduction, because that part is the most counterintuitive I 
think.  Accurately modeling the latency improvements of pooling requires 
much harder math, and it depends quite a bit on whether incoming traffic 
is even or in bursts.  Easier in many cases to just swallow expectations 
and estimates and just try it instead.

-- 
Greg Smith  2ndQuadrant US  Baltimore, MD
PostgreSQL Training, Services and Support
greg@2ndQuadrant.com   www.2ndQuadrant.us




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