Re: proposal: tuplestore, tuplesort aggregate functions

David Fetter <david@fetter.org> writes:
> Apart from the medians, which "median-like" aggregates do you have in
> mind to start with?  If you can provide examples of "median-like"
> aggregates that people might need to implement as user-defined
> aggregates, or other places where people would use this machinery, it
> will make your case stronger for this refactoring.

There would be plenty of scope to re-use the machinery without any
SQL-level extensions.  All you need is a polymorphic aggregate
transition function that maintains a tuplestore or whatever.
I don't see that extra syntax in CREATE AGGREGATE is really buying
much of anything.
        regards, tom lane