Re: Document aggregate functions better w.r.t. ORDER BY

On Wed, Oct 25, 2023 at 10:34:10PM -0700, David G. Johnston wrote:
> I would reword the existing note to be something like:
>
> The SQL Standard defines specific aggregates and their properties, including
> which of DISTINCT and/or ORDER BY is allowed.  Due to the extensible nature of
> PostgreSQL it accepts either or both clauses for any aggregate.

Uh, is this something in my patch or somewhere else?  I don't think
PostgreSQL extensible is an example of syntax flexibility.

> We get enough complaints regarding "apparent ordering" that I would like to
> add:
>
> As a reminder, while some DISTINCT processing algorithms produce sorted output
> as a side-effect, only by specifying ORDER BY is the output order guaranteed.

Well, we need to create a new email thread for this and look at all the
areas is applies to since this is a much larger issue.