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List:       postgresql-general
Subject:    Re: [HACKERS] improving GROUP BY estimation
From:       Tom Lane <tgl () sss ! pgh ! pa ! us>
Date:       2016-03-31 21:02:56
Message-ID: 8033.1459458176 () sss ! pgh ! pa ! us
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Alvaro Herrera <alvherre@2ndquadrant.com> writes:
> Tom Lane wrote:
>> See "Approximating block accesses in database organizations", S. B. Yao,
>> Communications of the ACM, Volume 20 Issue 4, April 1977 Pages 260-261

> That sounds nice all right, but I'm not sure it's actually helpful,
> because the article text is not available anywhere.  I doubt most people
> will spend 15 bucks to buy that paper ... so we don't actually know
> whether the paper supports the chosen formula :-)  unless you have a
> CACM subscription and can verify it.

Well, I do and I did, see my previous response.

> I think it's good to have the ACM reference anyway, for posterity, but
> it'd be good to (additionally) have something that people can read.

I'm just concerned about what happens when the Dellera paper stops being
available.  I don't mind including that URL as a backup to the written-out
argument I just suggested.

			regards, tom lane


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