Drop one-argument string_agg? (was Re: string_agg delimiter having no effect with order by)

Alex Hunsaker <badalex@gmail.com> writes:
> On Wed, Aug 4, 2010 at 11:04, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> If we were a bit earlier in the 9.0 cycle I would suggest that this
>> confusion is a sufficient reason to drop the one-argument form of
>> string_agg. It's too late now though.

> FWIW I think we can still change it.   Isn't this type of issue part
> of what beta is for?  If we were in RC that would be a different story
> :)

Well, it'd take an initdb to get rid of it.  In the past we've avoided
forcing initdb post-beta1 unless it was Really Necessary.  OTOH, we seem
to be in the mode of encouraging beta testers to test pg_upgrade, so
maybe that concern isn't worth much at the moment.

I am right, am I not, in thinking that we invented string_agg out of
whole cloth?  I don't see it in SQL:2008.  If there is a compatibility-
with-other-products reason to support the one-argument form, that would
be a consideration here.  I don't see a whole lot of functionality gain
from having the one-argument form, though.

BTW, as far as I can tell from checking in the system catalogs,
there are no other built-in aggregates that come in
differing-numbers-of-arguments variants.  So string_agg is the only
one presenting this hazard.
        regards, tom lane