Horton

Re: POC: GROUP BY optimization

Pavel Borisov <pashkin.elfe@gmail.com>

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From: Pavel Borisov <pashkin.elfe@gmail.com>
To: Dmitry Dolgov <9erthalion6@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: 2020-10-29T15:14:50Z
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

>
> In case if I'm missing something and Pavel's proposal is significantly
> different from the original patch (if I understand correctly, at the
> moment the latest patch posted here is a rebase and adjusting the old
> patch to work with the latest changes in master, right?), then indeed
> they could be merged, but please in the newer thread [1].
>

Sure, my patch has the only difference from the previous Theodor's code
for compatibility with v.13, though it is not small, and I appreciate the
changes in paths processing. The only thing that caused my notice, is that
some useful changes which I've mentioned before, are discarded now. But as
long as they are planned to be put in later it is completely fine. I agree
to discuss the thing in any thread, though I don't quite understand the
reason for a switch.

Still I don't see a problem.

-- 
Best regards,
Pavel Borisov

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