Re: Variadic aggregates vs. project policy

Andres Freund <andres@2ndquadrant.com> writes:
> On 2013-08-29 15:55:13 -0400, Tom Lane wrote:
>> For context see the thread starting here:
>> http://www.postgresql.org/message-id/AANLkTikV5ok2tS8t6V+gsAPtE3N6TJq1JpPhMZhG2XL0@mail.gmail.com
>> In that thread we agreed that this "policy" might be rather squishy,
>> but we should at least think hard about whether it would be wise to create
>> built-in aggregates with the same name and different numbers of arguments.

> I vote for abolishing that policy or maybe weakinging it. As you comment
> somewhere downthread the policy just prohibits core functions, but even
> for those it looks too strong for me. There are some useful variadic
> aggregates I'd like to see and I don't think that the kind of errors
> prevented by the policy are frequent enough to warrant a blanket
> prohibition.

Well, I dunno.  We had two different "bug reports" caused by this type of
confusion before string_agg even got out of beta, both from intelligent
people.  So I'm not about to discount the potential for confusion.

As we said originally, this is a policy that might be broken for
sufficiently strong cause --- but I don't want to just forget about
the risks.

> I'd say we let the check in there but have a list of exceptions in it so
> that one has to explicitly think about the issue before adding the
> function.

That's pretty much how the tests in opr_sanity work now.
        regards, tom lane