Tom,
> On further reflection, what the "policy" was actually about was not that
> we should forbid users from creating potentially-confusing aggregates
> themselves, but only that we'd avoid having any *built in* aggregates with
> this hazard. So maybe I'm overthinking this, and the correct reading is
> just that we should have a policy against built-in variadic aggregates.
Yes. I think we can assume that anyone smart enough to create a
variadic aggregate is smart enough to put ORDER BY in the right place.
--
Josh Berkus
PostgreSQL Experts Inc.
http://pgexperts.com