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