Re: [PATCH] Incremental sort

On Mon, Apr 3, 2017 at 10:05 PM, Andres Freund <andres(at)anarazel(dot)de> wrote:

> On April 3, 2017 12:03:56 PM PDT, Alexander Korotkov <
> a(dot)korotkov(at)postgrespro(dot)ru> wrote:
> >On Mon, Apr 3, 2017 at 9:34 PM, Andres Freund <andres(at)anarazel(dot)de>
> >wrote:
> >
> >> On 2017-03-29 00:17:02 +0300, Alexander Korotkov wrote:
> >> > On Tue, Mar 28, 2017 at 5:27 PM, David Steele <david(at)pgmasters(dot)net>
> >> wrote:
> >> > > On 3/20/17 10:19 AM, Heikki Linnakangas wrote:
> >> > >
> >> > >> On 03/20/2017 11:33 AM, Alexander Korotkov wrote:
> >> > >>
> >> > >>> Please, find rebased patch in the attachment.
> >> > >>>
> >> > >>
> >> > >> I had a quick look at this.
> >> > >>
> >> > >
> >> > > <...>
> >> > >
> >> > > According to 'perf', 85% of the CPU time is spent in
> >ExecCopySlot(). To
> >> > >> alleviate that, it might be worthwhile to add a special case for
> >when
> >> > >> the group contains exactly one group, and not put the tuple to
> >the
> >> > >> tuplesort in that case. Or if we cannot ensure that the
> >Incremental
> >> Sort
> >> > >> is actually faster, the cost model should probably be smarter,
> >to
> >> avoid
> >> > >> picking an incremental sort when it's not a win.
> >> > >>
> >> > >
> >> > > This thread has been idle for over a week. Please respond with a
> >new
> >> > > patch by 2017-03-30 00:00 AoE (UTC-12) or this submission will be
> >> marked
> >> > > "Returned with Feedback".
> >>
> >> > Thank you for reminder!
> >>
> >> I've just done so. Please resubmit once updated, it's a cool
> >feature.
> >>
> >
> >Thank you!
> >I already sent version of patch after David's reminder.
> >Please find rebased patch in the attachment.
>
> Cool. I think that's still a bit late for v10?
>

I don't know. ISTM, that I addressed all the issues raised by reviewers.
Also, this patch is pending since late 2013. It would be very nice to
finally get it in...

------
Alexander Korotkov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company