Re: Buffers from parallel workers not accumulated to upper nodes with gather merge

On Thu, 23 Jul 2020 15:44:16 +0530
Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:

> On Tue, Jul 21, 2020 at 9:05 PM Jehan-Guillaume de Rorthais
> <jgdr(at)dalibo(dot)com> wrote:
> >
> > On Mon, 20 Jul 2020 15:29:00 +0530
> > Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> >
> >
> > > BTW, can you please test if the problem exist in back-branches, and does
> > > your change fix it there as well?
> >
> > Gather Merge appears in v10, but I haven't been able to produce a plan
> > using it.
>
> I am able to do it for v10. I think you can try by "set
> enable_hashagg = off;" and following all other steps mentioned in your
> email?

Indeed. I confirm it produces the same result. I've been able to successfully
test to proposed fix.

> Attached, please find the patch for v10 with a modified commit
> message. I will do it for other versions as well if you are fine with
> it?

I'm not an english-native writer, but I would rephrase this:

We can do a similar thing for Gather Merge as well but it seems the better
to account for stats during nodes shutdown after completing the execution.

Thanks!

Regards,