Re: proposal: tuplestore, tuplesort aggregate functions

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: David Fetter <david(at)fetter(dot)org>, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: proposal: tuplestore, tuplesort aggregate functions
Date: 2010-08-19 20:21:30
Message-ID: 27029.1282249290@sss.pgh.pa.us
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Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> You've made this assertion at least three times now, but I confess
> that I've only ever learned one way to compute a median; and quick
> Google searches for "median", "kinds of median", and few other
> variants failed to turn up anything obvious either.

There are different ways to define it when the number of samples is even.
However I believe that "use the mean of the two middle values" is much
the most common way to deal with that.

regards, tom lane

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