Re: Eager aggregation, take 3 - Mailing list pgsql-hackers

On Tue, Nov 12, 2024 at 1:30 AM Robert Haas <robertmhaas@gmail.com> wrote:
> On Sun, Nov 10, 2024 at 7:52 PM Richard Guo <guofenglinux@gmail.com> wrote:
> > Hmm, currently we only consider grouped aggregation for eager
> > aggregation.  For grouped aggregation, the window function's
> > arguments, as well as the PARTITION BY expressions, must appear in the
> > GROUP BY clause.  That is to say, the depname column in the first
> > query, or the n column in the second query, will not be aggregated
> > into the partial groups.  Instead, they will remain as they are as
> > input for the WindowAgg nodes.  It seems to me that this ensures
> > that we're good with window functions.  But maybe I'm wrong.
>
> Unfortunately, I don't know what you mean by grouped aggregation. I
> think of grouping and aggregation as synonyms, pretty much.

Ah, sorry for the confusion.  By "grouped aggregation", I mean
aggregation with a GROUP BY clause, where we produce a result row for
each group.  This contrasts with plain aggregation, where there is a
single result row for the whole query.

Thanks
Richard