Re: [PATCH] Incremental sort

On Thu, Apr 27, 2017 at 5:06 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:

> On Wed, Apr 26, 2017 at 11:39 AM, Alexander Korotkov
> <a(dot)korotkov(at)postgrespro(dot)ru> wrote:
> > But I'd like to make incremental sort not slower than quicksort in case
> of
> > presorted data. New idea about it comes to my mind. Since cause of
> > incremental sort slowness in this case is too frequent reset of
> tuplesort,
> > then what if we would artificially put data in larger groups. Attached
> > revision of patch implements this: it doesn't stop to accumulate tuples
> to
> > tuplesort until we have MIN_GROUP_SIZE tuples.
> >
> > Now, incremental sort is not slower than quicksort. And this seems to be
> > cool.
> > However, in the LIMIT case we will pay the price of fetching some extra
> > tuples from outer node. But, that doesn't seem to hurt us too much.
> >
> > Any thoughts?
>
> Nice idea.

Cool.
Than I'm going to make a set of synthetic performance tests in order to
ensure that there is no regression.

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