Horton

Re: POC: GROUP BY optimization

Dmitry Dolgov <9erthalion6@gmail.com>

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From: Dmitry Dolgov <9erthalion6@gmail.com>
To: Teodor Sigaev <teodor@sigaev.ru>
Cc: GavinFlower@archidevsys.co.nz, Michael Paquier <michael@paquier.xyz>, PostgreSQL Developers <pgsql-hackers@lists.postgresql.org>, Tomas Vondra <tomas.vondra@2ndquadrant.com>
Date: 2018-11-29T16:56:53Z
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 Tue, Oct 2, 2018 at 4:16 AM Michael Paquier <michael@paquier.xyz> wrote:
>
> On Sat, Jun 30, 2018 at 09:19:13AM +1200, Gavin Flower wrote:
> > Additionally put an upper limit threshold on the number of combinations to
> > check, fairly large by default?
> >
> > If first threshold is exceeded, could consider checking out a few more
> > selected at random from paths not yet checked, to avoid any bias caused by
> > stopping a systematic search.  This might prove important when N! is fairly
> > large.
>
> Please note that the latest patch available does not apply, so this has
> been moved to next CF 2018-11, waiting for input from its author.

Unfortunately, patch still has some conflicts, could you please rebase it?