Re: Eager aggregation, take 3

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.

Returning to this point now that I understand what you meant by
grouped aggregation:

I still don't understand how you expect to be able to evaluate
functions like LEAD() and LAG() if any form of partial aggregation has
been done.

--
Robert Haas
EDB: http://www.enterprisedb.com