Horton

Re: Correction of RowMark Removal During Sel-Join Elimination

Alexander Korotkov <aekorotkov@gmail.com>

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From: Alexander Korotkov <aekorotkov@gmail.com>
To: Andrei Lepikhov <lepihov@gmail.com>
Cc: Greg Sabino Mullane <htamfids@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2025-08-24T00:44:38Z
Lists: pgsql-hackers

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Hi, Andrei!

On Tue, Aug 12, 2025 at 12:40 PM Andrei Lepikhov <lepihov@gmail.com> wrote:
> On 11/8/2025 20:15, Greg Sabino Mullane wrote:
> > I'm not convinced this is an improvement from someone just coming in to
> > this part of the code, especially given (for example) the comment right
> > above it:
> >
> >   * Determine if the inner table can duplicate outer rows.  We must
> >   * bypass the unique rel cache here since we're possibly using aThanks for your feedback.
> I made some minor adjustments to the comments to make the code more
> consistent. Sure, rrel and krel don't seem like the best solution - I
> guess natives could find less wordy synonyms than just dumb
> 'keeping_rel' and 'removing_rel'. But it is simpler to track which
> relation and RowMark should be removed.

Thank you for catching this.  And thank you for the fix.  I think it
worth separating fix and refactoring.  This helps to understand what
exactly the fix is by looking at the patch.  I also edited commit
message.  I'm going to push this if no objections.

------
Regards,
Alexander Korotkov
Supabase

Commits

  1. Improve RowMark handling during Self-Join Elimination

  2. Refactor variable names in remove_self_joins_one_group()

  3. Reduce "Var IS [NOT] NULL" quals during constant folding

  4. Reimplement parsing and storage of default expressions and constraint