Horton

Re: BUG #19435: Error: "No relation entry for relid 2" Triggered by Complex Join with Self-Referencing Tables

Alexander Korotkov <aekorotkov@gmail.com>

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From: Alexander Korotkov <aekorotkov@gmail.com>
To: Andrei Lepikhov <lepihov@gmail.com>
Cc: Tender Wang <tndrwang@gmail.com>, Kirill Reshke <reshkekirill@gmail.com>, Fujii Masao <masao.fujii@gmail.com>, ammmkilo@163.com, pgsql-bugs@lists.postgresql.org
Date: 2026-03-18T12:21:34Z
Lists: pgsql-bugs 
On Wed, Mar 18, 2026 at 2:18 PM Andrei Lepikhov <lepihov@gmail.com> wrote:
>
> On 18/3/26 09:40, Alexander Korotkov wrote:
> > What about being more generic and call ChangeVarNodes_walker() for the
> > node in ChangeVarNodesWalkExpression()?  It also works with out case
> > and avoids code duplication.
> I’ve reached the same conclusion. We lost a possible case when the
> RestrictInfo→clause contains a bare Var that isn’t pushed into either
> the left or right subtree.
> I think we can fix this by replacing the expression walker with
> ChangeVarNodes_walker().

I see.  This is even better.

> What is the reason for the second change? Tender, can you show us how to
> reproduce the issue so we can support your update to
> restrict_infos_logically_equal? If we include it, we should add a test.

I think Tender already shown this in [1].  The same qual is present
twice in the plan.

Links.
1. https://www.postgresql.org/message-id/CAHewXN%3D7kDJjUcgEm%2B6qhaKOXuqzvhRqAAKdafNCRgn0yH7BGg%40mail.gmail.com

------
Regards,
Alexander Korotkov
Supabase

Commits

  1. Further improve commentary about ChangeVarNodesWalkExpression()

  2. Improve commentary about ChangeVarNodesWalkExpression().

  3. Fix self-join removal to update bare Var references in join clauses

  4. Implement Self-Join Elimination