On Thu, Oct 26, 2023 at 2:56 PM Bruce Momjian <br...@momjian.us> wrote:
> 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. > https://www.postgresql.org/docs/current/sql-expressions.html#SYNTAX-AGGREGATES Note The ability to specify both DISTINCT and ORDER BY in an aggregate function is a PostgreSQL extension. I am pointing out that the first sentence of the existing note above seems to be factually incorrect. I tried to make it correct - while explaining why we differ. Though in truth I'd probably rather just remove the note. > 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. > > I was hoping to sneak this one in regardless of the bigger picture issues, since this specific combination is guaranteed to output ordered presently. David J.
