Обсуждение: 9.4rc bug in percentile_cont

Just got a report on IRC of a bug in the array version of
percentile_cont; if two of the requested percentiles were between the
same pair of input rows, the result could be wrong or an error would
be generated.

e.g.

select percentile_cont(array[0.4,0.6]) within group (order by gs)
  from generate_series(1,2) gs;
ERROR: missing row in percentile_cont

Proposed patch (against current master) attached.

--
Andrew (irc:RhodiumToad)

Andrew Gierth <andrew@tao11.riddles.org.uk> writes:
> Just got a report on IRC of a bug in the array version of
> percentile_cont; if two of the requested percentiles were between the
> same pair of input rows, the result could be wrong or an error would
> be generated.

Oooh, good catch.

> Proposed patch (against current master) attached.

I think this patch could be improved a bit; will work on it.
        regards, tom lane