Re: wip: functions median and percentile

Hitoshi Harada <umi(dot)tanuki(at)gmail(dot)com> writes:
> 2010/10/2 Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>:
>> The implementation I would've expected to see is to do the sort and then
>> have two code paths for retrieving the median, depending on whether the
>> sort result is all in memory or not.

> Hm? The problem we encountered in the middle of the patch is there is
> no chance to call tuplesort_end if median is called in moving frame
> window aggregate because final function is called multiple times
> during moving.

Well, if you haven't got a solution for that, then this patch isn't
ready for prime time.

It's entirely possible that median as a window function is intractable.
I'd rather have it throwing error than offer an implementation that will
fall over as soon as the window gets large.

regards, tom lane