Subject: Re: benchmarking the query planner
From: Simon Riggs <simon@2ndQuadrant.com>
To: Gregory Stark <stark@enterprisedb.com>
Cc: Robert Haas <robertmhaas@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>,
	Kevin Grittner <Kevin.Grittner@wicourts.gov>,
	"jd@commandprompt.com" <jd@commandprompt.com>,
	Josh Berkus <josh@agliodbs.com>, Greg Smith <gsmith@gregsmith.com>,
	pgsql-hackers@postgresql.org
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Date: Fri, 12 Dec 2008 17:09:57 +0000
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On Fri, 2008-12-12 at 16:10 +0000, Gregory Stark wrote:
> Uhm, this is a survey of lots of different methods and does lots of
> analysis.
> I don't see any simple conclusions about stability. Perhaps I'm just
> missing
> it in the technical details. Could you point out exactly what part of
> the
> paper you're basing this on and what "stable" means?

I was echoing the comments in the ANALYZE code, which explain that we
use the Duj1 estimator because it is more stable across sample size, as
shown in table 5 on p.21 of the Haas Stokes report.

-- 
 Simon Riggs           www.2ndQuadrant.com
 PostgreSQL Training, Services and Support