Re: improving GROUP BY estimation

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/
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