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

On Wed, Aug 04, 2010 at 06:19:49PM -0400, Tom Lane wrote:
> I wrote:
> > Hm? I don't think that an initdb here would have any impact on whether
> > we can call the next drop RC1 or not. We're talking about removing a
> > single built-in entry in pg_proc --- it's one of the safest changes we
> > could possibly make.
>
> Well, I forgot that an aggregate involves more than one catalog row ;-).
> So it's a bit bigger patch than that, but still pretty small and safe.
> See attached.
>
> What we are doing here, IMO, is not just changing string_agg() but
> instituting a project policy that we are not going to offer built-in
> aggregates with the same names and different numbers of arguments ---
> otherwise the problem will come right back. Therefore, the attached
> patch adds an opr_sanity regression test that will complain if anyone
> tries to add such. Of course, this isn't preventing users from creating
> such aggregates, but it's on their own heads to not get confused if they
> do.
>
> This policy also implies that we are never going to allow default
> arguments for aggregates, or at least never have any built-in ones
> that use such a feature.
>
> By my count the following people had offered an opinion on making
> this change:
> for: tgl, josh, badalex, mmoncure
> against: rhaas, thom
> Anybody else want to vote, or change their vote after seeing the patch?

+1 for removing the single-argument version.

Cheers,
David.
--
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