Re: 8.2 is 30% better in pgbench than 8.3

From: Greg Smith <gsmith(at)gregsmith(dot)com>
To: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: 8.2 is 30% better in pgbench than 8.3
Date: 2007-07-22 05:58:25
Message-ID: Pine.GSO.4.64.0707220134200.20660@westnet.com
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On Sat, 21 Jul 2007, Tom Lane wrote:

> With autovac off I see 8.3 as faster than 8.2 in pgbench.

Indeed. I'm seeing much better pgbench results from HEAD than 8.2 when I
set the configurations up identically. I'm hoping to have a comparison
set to show everyone this week.

> and use -t at least 1000 or so (otherwise startup transients are
> significant).

I personally consider any pgbench run that lasts less than several minutes
noise. On a system that hits 500 TPS like Pavel's, I'd want to see around
100,000 transactions before I consider the results significant. And then
I'd want a set of 3 at each configuration because even with longer runs,
you occasionally get really odd results. Until you have 3 it can be
unclear which is the weird one.

--
* Greg Smith gsmith(at)gregsmith(dot)com http://www.gregsmith.com Baltimore, MD

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