Re: multi-column aggregates

[Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>]

Chris Kratz <chris(dot)kratz(at)vistashare(dot)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