Re: Removing unneeded self joins

Andrei Lepikhov <a.lepikhov@postgrespro.ru>

From: Andrey Lepikhov <a.lepikhov@postgrespro.ru>

To: Andres Freund <andres@anarazel.de>

Cc: Zhihong Yu <zyu@yugabyte.com>, Ronan Dunklau <ronan.dunklau@aiven.io>, Greg Stark <stark@mit.edu>, Laurenz Albe <laurenz.albe@cybertec.at>, Hywel Carver <hywel@skillerwhale.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>

Date: 2022-12-16T06:45:30Z

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 →

Remove GUC_NOT_IN_SAMPLE from enable_self_join_elimination
- 717d0e8dd945 18.0 landed
Put enable_self_join_elimination into postgresql.conf.sample
- c2d329260cd8 18.0 landed
Get rid of ojrelid local variable in remove_rel_from_query()
- e167191dc146 18.0 landed
Implement Self-Join Elimination
- fc069a3a6319 18.0 cited
Revert: Remove useless self-joins
- d1d286d83c0e 17.0 landed
Replace lateral references to removed rels in subqueries
- 466979ef031a 17.0 landed
Replace relids in lateral subquery parse tree during SJE
- 489072ab7a9e 17.0 landed
Forbid SJE with result relation
- 8c441c082797 17.0 landed
Fix misuse of RelOptInfo.unique_for_rels cache by SJE
- 30b4955a4668 17.0 landed
Replace the relid in some missing fields during SJE
- a7928a57b9f0 17.0 landed
Revert 56-bit relfilenode change and follow-up commits.
- a448e49bcbe4 16.0 cited
Stabilize timetz test across DST transitions.
- 4a071afbd056 14.0 cited
Speed up finding EquivalenceClasses for a given set of rels
- 3373c7155350 13.0 cited
Fix mark-and-restore-skipping test case to not be a self-join.
- 24d08f3c0a1f 12.0 landed

Attachments

v39-0001-Remove-self-joins.patch (text/x-patch) patch v39-0001

On 12/6/22 23:46, Andres Freund wrote:
> This doesn't pass the main regression tests due to a plan difference.
> https://cirrus-ci.com/task/5537518245380096
> https://api.cirrus-ci.com/v1/artifact/task/5537518245380096/testrun/build/testrun/regress/regress/regression.diffs
> 
> diff -U3 /tmp/cirrus-ci-build/src/test/regress/expected/join.out /tmp/cirrus-ci-build/build/testrun/regress/regress/results/join.out
> --- /tmp/cirrus-ci-build/src/test/regress/expected/join.out	2022-12-05 19:11:52.453920838 +0000
> +++ /tmp/cirrus-ci-build/build/testrun/regress/regress/results/join.out	2022-12-05 19:15:21.864183651 +0000
> @@ -5806,7 +5806,7 @@
>    Nested Loop
>      Join Filter: (sj_t3.id = sj_t1.id)
>      ->  Nested Loop
> -         Join Filter: (sj_t3.id = sj_t2.id)
> +         Join Filter: (sj_t2.id = sj_t3.id)
>            ->  Nested Loop Semi Join
>                  ->  Nested Loop
>                        ->  HashAggregate
This change in the test behaviour is induced by the a5fc4641
"Avoid making commutatively-duplicate clauses in EquivalenceClasses."
Nothing special, as I see. Attached patch fixes this.

-- 
Regards
Andrey Lepikhov
Postgres Professional