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Re: More thoughts about planner's cost estimates

From: David Fetter <david(at)fetter(dot)org>
To: Michael Dean <mdean(at)sourceview(dot)com>
Cc: Greg Stark <gsstark(at)mit(dot)edu>, josh(at)agliodbs(dot)com,Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: More thoughts about planner's cost estimates
Date: 2006-06-02 20:56:11
Message-ID: 20060602205611.GA23684@fetter.org (view raw or flat)
Thread:
Lists: pgsql-hackers
On Fri, Jun 02, 2006 at 01:39:32PM -0700, Michael Dean wrote:

> I'm sorry to interrupt your esoteric (to me) discussion, but I have
> a very simple question:  would you define a "good unbiased sample"?
> My statistics professor Dan Price (rest his soul) would tell me
> there are only random samples of some sort, and "other", which are
> always biased, and never good.

What's at issue here is a biased estimator, not a biased sample.  If
you know an unbiased estimator of multiplicity based on a random
sample, that would be a great :)

Cheers,
D
-- 
David Fetter <david(at)fetter(dot)org> http://fetter.org/
phone: +1 415 235 3778        AIM: dfetter666
                              Skype: davidfetter

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