"David G. Johnston" <david.g.johnston@gmail.com> writes:
> Can we please add "first_value" and "last_value" if we are going to add
> "some_random_value" to our library of aggregates?
First and last according to what ordering? We have those in the
window-aggregate case, and I don't think we want to encourage people
to believe that "first" and "last" are meaningful otherwise.
ANY_VALUE at least makes it clear that you're getting an unspecified
one of the inputs.
regards, tom lane