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Date: Thu, 31 Mar 2016 17:34:07 -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
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Tom Lane wrote:

> Another minor gripe is the use of a random URL as justification.  This
> code will still be around when that URL exists nowhere but the Wayback
> Machine.  Can't we find a more formal citation to use?

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 

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


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