Re: Allow a prosupport function to be attached to an aggregate

Andrei Lepikhov <lepihov(at)gmail(dot)com> writes:
> Also, I'm not sure why pg_dump/upgrade has not been implemented. So, I
> added an 'unsupported' clause into the docs - let's discuss it later or
> correct me if such a feature can't be supported at all.

Shame on me, I didn't think about that angle.

After reflection I realized that the approach I took in my first patch
is wrong: letting ALTER FUNCTION work on an aggregate is pretty
non-orthogonal, if the only property it can set is SUPPORT. The right
way to do this is to add a SUPPORT option to CREATE AGGREGATE, which
slots nicely into getting pg_dump to handle it. As attached.

One thing I don't quite love about this is that the CREATE AGGREGATE
docs already refer to transfn, finalfn, etc as "support functions",
so that there's a potential for confusion as to what SUPPORT really
means. I considered naming the option something else, but it feels
wrong to not use the same name as in CREATE FUNCTION. Any other
opinions about that?

regards, tom lane