On Wed, Aug 28, 2024 at 9:01 PM Robert Haas <robertmhaas@gmail.com> wrote: > On Tue, Aug 27, 2024 at 11:57 PM Tender Wang <tndrwang@gmail.com> wrote: > > I haven't look all of them. I just pick few simple plan test(e.g. 19.sql, 45.sql). > > For example, 19.sql, eager agg pushdown doesn't get large gain, but a little > > performance regress. > > Yeah, this is one of the things I was worried about in my previous > reply to Richard. It would be worth Richard, or someone, probing into > exactly why that's happening. My fear is that we just don't have good > enough estimates to make good decisions, but there might well be > another explanation.
It's great that we have a query to probe into. Your guess is likely correct: it may be caused by poor estimates.
Tender, would you please help provide the outputs of
EXPLAIN (COSTS ON, ANALYZE)
on 19.sql with and without eager aggregation?
I upload EXPLAIN(COSTS ON, ANALYZE) test to [1].
I ran the same query three times, and I chose the third time result.
You can check 19_off_explain.out and 19_on_explain.out.
