[postgis-users] Parallel spatial indexing for GiST?

Darafei "Komяpa" Praliaskouski me at komzpa.net
Mon Sep 21 00:40:09 PDT 2020


Hello Marco,

Scope for PG13 was fixed half a year ago. This is up for PG14, and needs
your care and help to happen - there is a possibility to get it in
parallel, since this sorting build is still single thread.

On Thu, Sep 17, 2020 at 12:24 AM Marco Boeringa <marco at boeringa.demon.nl>
wrote:

> Thanks Peter,
>
> That certainly looks promising, and it is heartening to see real work
> already being done, although there appears to be no mention of Polygon
> type data being tested as well, but I don't know if geometry type is
> actually relevant to developing a faster GiST (spatial) index build.
> Probably not.
>
> 10x improvement would be great... love to see that land in PostgreSQL 13!
>
> Marco
>
> Op 16-9-2020 om 22:13 schreef Peter Geoghegan:
> > On Wed, Sep 16, 2020 at 12:54 PM Marco Boeringa <marco at boeringa.demon.nl>
> wrote:
> >> Appreciate your insights. Good to hear there appear to be opportunities
> >> for improvements to GiST index build speed in the future, even if no
> >> active work is being done right now. Yes, I do think a lot of people,
> >> and an increasing number, could benefit from such work. I personally
> >> would certainly applaud any improvements being made, as it is especially
> >> clear that disk speed is not an issue in most of the processing
> >> involved, and disk speed therefor unlikely to become limiting with any
> >> improvements in index creation, meaning there is likely a good
> >> opportunity for improving GiST index build speed.
> > Actually, there is ongoing work to speed up GiST index builds by using
> > Z-order + sorting:
> >
> > https://postgr.es/m/123F5F32-9A85-4D0B-9C7A-1686E6BBE15D@yandex-team.ru
> >
> > It reportedly can be as much as 10x faster. Building the index through
> > sorting rather than using retail inserts is inherently much faster.
> > And, we've put a lot of effort into speeding up B-Tree index
> > builds/sorting over several releases, to the point where a B-Tree
> > index build can be very I/O bound even on high end hardware. It seems
> > possible that GiST could get much of the benefit of that work by
> > adopting index builds to use Z-order.
> >
> > The tricky part may be getting that benefit without significantly
> > impacting the final index structure. The idea of teaching GiST to
> > build indexes in a way that's a lot closer to B-Tree seems very
> > promising, though.
> >
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