Re: Window Function "Run Conditions"

On Tue, 5 Apr 2022 at 19:38, Andy Fan <zhihui.fan1213@gmail.com> wrote:
> 1. We can do more on PASSTHROUGH, we just bypass the window function
> currently,  but IIUC we can ignore all of the following tuples in current partition
> once we go into this mode.  patch 0001 shows what I mean.

Yeah, there is more performance to be had than even what you've done
there.  There's no reason really for spool_tuples() to do
tuplestore_puttupleslot() when we're not in run mode.

The attached should give slightly more performance.  I'm unsure if
there's more that can be done for window aggregates, i.e.
eval_windowaggregates()

I'll consider the idea about doing all the filtering in
nodeWindowAgg.c. For now I made find_window_run_conditions() keep the
qual so that it's still filtered in the subquery level when there is a
PARTITION BY clause. Probably the best way would be to make
nodeWindowAgg.c just loop with a for(;;) loop. I'll need to give it
more thought. I'll do that in the morning.

David