Chris Kratz <chris.kratz@vistashare.com> writes:
> Thanks for the reply. Yes, subselects would work very well and in some ways
> are more elegant then the hand waving we had to do to get the multi-column
> aggregates to work.
BTW, there is not any fundamental reason why we can't support aggregate
functions with multiple inputs. I looked at this not long ago and
determined that the major stumbling blocks would be
(1) trying to keep the code in nodeAgg.c from getting a lot more
complicated and hence slower for the single-input case;
(2) figuring out how to change the syntax for CREATE AGGREGATE.
It certainly seems doable if someone wants to spend time on it.
regards, tom lane