Re: proposal: tuplestore, tuplesort aggregate functions

On Thu, Aug 19, 2010 at 4:21 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> 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.

I suppose there could also be a bit of an ambiguity if you're working
with a type like int4 where the values are discrete steps. Like, what
do you do with {1, 2}?

--
Robert Haas
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