Horton

Re: POC: GROUP BY optimization

Dmitry Dolgov <9erthalion6@gmail.com>

View thread
From: Dmitry Dolgov <9erthalion6@gmail.com>
To: Pavel Borisov <pashkin.elfe@gmail.com>
Cc: Tomas Vondra <tomas.vondra@2ndquadrant.com>, Teodor Sigaev <teodor@sigaev.ru>, Gavin Flower <GavinFlower@archidevsys.co.nz>, Andres Freund <andres@anarazel.de>, Michael Paquier <michael@paquier.xyz>, PostgreSQL Developers <pgsql-hackers@lists.postgresql.org>
Date: 2020-10-26T08:57:21Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Restore preprocess_groupclause()

  2. Rename PathKeyInfo to GroupByOrdering

  3. Add invariants check to get_useful_group_keys_orderings()

  4. Fix asymmetry in setting EquivalenceClass.ec_sortref

  5. Multiple revisions to the GROUP BY reordering tests

  6. Get rid of pg_class usage in SJE regression tests

  7. Rename index "abc" in aggregates.sql

  8. Explore alternative orderings of group-by pathkeys during optimization.

  9. Generalize the common code of adding sort before processing of grouping

  10. Fix out-dated comment in preprocess_groupclause()

  11. Force parallelism in partition_aggregate

  12. Optimize order of GROUP BY keys

> On Mon, Oct 26, 2020 at 12:44:58PM +0400, Pavel Borisov wrote:
> >
> >
> > I wonder if anyone has plans to try again with this optimization in v14
> > cycle? The patches no longer apply thanks to the incremental sort patch,
> > but I suppose fixing that should not be extremely hard.
> >
> > I found this feature interesting and I'd like to join.
> PFA the updated version of the patch made fully compatible with changes in
> v13 and I suppose it is ready to be reviewed for v14.
>
> Main things changed:
> 1. Patch is made compatible with new lists representation ( 1cff1b95ab6d )
> 2. Patch is made compatible with the incremental sort ( d2d8a229bc58 and
> ba3e76cc571e )
> 3. Tests are changed to represent changes in keys numbering and
> naming convention in the plan ( 55a1954da16 and 6ef77cf46e8 )
>
> As always your ideas are very much welcome!

Hi,

Thanks for your interest! FYI there is a new thread about this topic [1]
with the next version of the patch and more commentaries (I've created
it for visibility purposes, but probably it also created some confusion,
sorry for that).

[1]: https://www.postgresql.org/message-id/flat/CA%2Bq6zcW_4o2NC0zutLkOJPsFt80megSpX_dVRo6GK9PC-Jx_Ag%40mail.gmail.com