Horton

Re: Removing unneeded self joins

Andrei Lepikhov <a.lepikhov@postgrespro.ru>

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From: Andrey Lepikhov <a.lepikhov@postgrespro.ru>
To: Hywel Carver <hywel@skillerwhale.com>
Cc: Konstantin Knizhnik <knizhnik@garret.ru>, Heikki Linnakangas <hlinnaka@iki.fi>, David Rowley <dgrowleyml@gmail.com>, Masahiko Sawada <sawada.mshk@gmail.com>, pgsql-hackers@lists.postgresql.org
Date: 2021-05-07T07:23:00Z
Lists: pgsql-hackers

Commits

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  1. Remove GUC_NOT_IN_SAMPLE from enable_self_join_elimination

  2. Put enable_self_join_elimination into postgresql.conf.sample

  3. Get rid of ojrelid local variable in remove_rel_from_query()

  4. Implement Self-Join Elimination

  5. Revert: Remove useless self-joins

  6. Replace lateral references to removed rels in subqueries

  7. Replace relids in lateral subquery parse tree during SJE

  8. Forbid SJE with result relation

  9. Fix misuse of RelOptInfo.unique_for_rels cache by SJE

  10. Replace the relid in some missing fields during SJE

  11. Revert 56-bit relfilenode change and follow-up commits.

  12. Stabilize timetz test across DST transitions.

  13. Speed up finding EquivalenceClasses for a given set of rels

  14. Fix mark-and-restore-skipping test case to not be a self-join.

Attachments

On 12/3/21 14:05, Hywel Carver wrote:
> I've built and tested this, and it seems to function correctly to me. One question I have is whether the added "IS NOT NULL" filters can be omitted when they're unnecessary. Some of the resulting plans included an "IS NOT NULL" filter on a non-nullable column. To be clear, this is still an improvement (to me) without that.

New version of the feature. Deeply refactored with main goal - to reduce 
the code size) and rebased on current master.

Here I didn't work on 'unnecessary IS NOT NULL filter'.

-- 
regards,
Andrey Lepikhov
Postgres Professional