Re: POC: GROUP BY optimization

Pavel Borisov <pashkin.elfe@gmail.com>

From: Pavel Borisov <pashkin.elfe@gmail.com>

To: Tomas Vondra <tomas.vondra@2ndquadrant.com>

Cc: Dmitry Dolgov <9erthalion6@gmail.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: 2020-10-26T08:44:58Z

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 →

Restore preprocess_groupclause()
- 505c008ca37c 17.0 landed
Rename PathKeyInfo to GroupByOrdering
- 0c1af2c35c7b 17.0 landed
Add invariants check to get_useful_group_keys_orderings()
- 91143c03d4ca 17.0 landed
Fix asymmetry in setting EquivalenceClass.ec_sortref
- 199012a3d844 17.0 landed
Multiple revisions to the GROUP BY reordering tests
- 874d817baa16 17.0 landed
Get rid of pg_class usage in SJE regression tests
- e1b7fde418f2 17.0 landed
Rename index "abc" in aggregates.sql
- b91f91870828 17.0 landed
Explore alternative orderings of group-by pathkeys during optimization.
- 0452b461bc40 17.0 landed
Generalize the common code of adding sort before processing of grouping
- 7ab80ac1caf9 17.0 landed
Fix out-dated comment in preprocess_groupclause()
- f6c70b81802a 15.0 landed
- 78a9af1a2764 16.0 landed
Force parallelism in partition_aggregate
- 2fe6b2a806f2 16.0 landed
- 01474f56981a 15.0 landed
Optimize order of GROUP BY keys
- db0d67db2401 15.0 landed

Attachments

v11-0001-GROUP-BY-optimization-made-compatible-with-chang.patch (application/octet-stream) patch v11-0001

>
>
> 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!

-- 
Best regards,
Pavel Borisov

Postgres Professional: http://postgrespro.com <http://www.postgrespro.com>