Date: Thu, 31 Mar 2016 17:51:18 -0300
From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Dean Rasheed <dean.a.rasheed@gmail.com>,
	Tomas Vondra <tomas.vondra@2ndquadrant.com>,
	Alexander Korotkov <a.korotkov@postgrespro.ru>,
	Mark Dilger <hornschnorter@gmail.com>,
	PostgreSQL-development <pgsql-hackers@postgresql.org>
Subject: Re: improving GROUP BY estimation
Message-ID: <20160331205118.GA166096@alvherre.pgsql>
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Tom Lane wrote:

> > The article text refers to this 1977 S. B. Yao paper "Approximating
> > block accesses in database organizations" which doesn't appear to be
> > available online, except behind ACM's paywall at
> > http://dl.acm.org/citation.cfm?id=359475 
> 
> Well, a CACM citation is perfectly fine by my lights (especially one
> that's that far back and therefore certainly patent-free ...)
> 
> Let's use something like this:
> 
> 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.

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.

-- 
Álvaro Herrera                http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services


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