Re: Minor performance improvement in transition to external sort

On Thu, Apr 10, 2014 at 06:03:15PM +0100, Simon Riggs wrote:
> On 6 February 2014 18:21, Jeff Janes <jeff(dot)janes(at)gmail(dot)com> wrote:
> > On Tue, Feb 4, 2014 at 2:22 PM, Jeremy Harris <jgh(at)wizmail(dot)org> wrote:
> >>
> >> The attached patch replaces the existing siftup method for heapify with
> >> a siftdown method. Tested with random integers it does 18% fewer
> >> compares and takes 10% less time for the heapify, over the work_mem
> >> range 1024 to 1048576.
> >
> >
> > Thanks for working on this.
>
> +1
>
> Your patch isn't linked properly from the CF manager though.
>
> If you like patches like this then there's a long(er) list of
> optimizations already proposed previously around sorting. It would be
> good to have someone work through them for external sorts. I believe
> Noah is working on parallel internal sort (as an aside).
>
> There's also an optimization possible for merge joins where we use the
> output of the first sort as an additional filter on the second sort.
> That can help when we're going to join two disjoint tables.

Where should this be recorded? TODO? Commitfest manager?

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

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