Re: Multi-parameter aggregates.

Joe Conway wrote:
> Berend Tober wrote:
> 
>> I'm stuck on not knowing how to define a aggregate that takes more 
>> that one variable as its argument
But I guess it _could_ take an array as argument, maybe even
a record (postgresql pseudonym for what's called a structure in C).

You'd use it with the following syntax (array):
select covariance(array[x, y]) from t ;

or, for a "record"-parameter (I didn't test it - I just
guess that it should work...)
select covariance((x, y)) from t ;

greetings, Florian Pflug