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help / color / mirror / Atom feedFrom: Alexander Korotkov <aekorotkov@gmail.com>
To: Andrei Lepikhov <lepihov@gmail.com>
Cc: Kirill Reshke <reshkekirill@gmail.com>
Cc: Tender Wang <tndrwang@gmail.com>
Cc: Fujii Masao <masao.fujii@gmail.com>
Cc: ammmkilo@163.com
Cc: pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #19435: Error: "No relation entry for relid 2" Triggered by Complex Join with Self-Referencing Tables
Date: Thu, 19 Mar 2026 15:03:17 +0200
Message-ID: <CAPpHfdsyNYEbjjLdsa8i8Ds-5=4pFif1+uCHn3vwzx2Pq5y29A@mail.gmail.com> (raw)
In-Reply-To: <5a039d60-d13b-4cf0-a807-9c7269f06831@gmail.com>
References: <19435-3cc1a87f291129f1@postgresql.org>
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On Thu, Mar 19, 2026 at 9:18 AM Andrei Lepikhov <lepihov@gmail.com> wrote:
> On 18/3/26 18:55, Kirill Reshke wrote:
> > On Wed, 18 Mar 2026 at 18:31, Andrei Lepikhov <lepihov@gmail.com> wrote:
> >>
> >> On 18/3/26 13:21, Alexander Korotkov wrote:
> >>> On Wed, Mar 18, 2026 at 2:18 PM Andrei Lepikhov <lepihov@gmail.com> wrote:
> >>>> 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.
> >> Got it. I suggest making this a separate commit to keep the history
> >> clear. Let me share a draft with a test case for the bug fix first.
> > Hi!
> > Is `cool_bool` a typo of `col_bool` in regression test ?
>
> This is actually a happy coincidence, not a typo. We made this mistake
> during initial development because I didn't realise that a boolean
> operation on a bool variable is never wrapped in an expression
> structure. It's a 'cool' example that shows a rare edge case.
>
> > And the patch seems to have forgotten to add "Reported by".
>
> Yeah, let the committer manage the award part.
I've revised the patch. Renamed cool_bool to cool_col, added
"Reported by", and revised authors list according to my opinion.
------
Regards,
Alexander Korotkov
Supabase
Attachments:
[application/octet-stream] v2-0001-Fix-self-join-removal-to-update-bare-Var-referenc.patch (3.9K, 2-v2-0001-Fix-self-join-removal-to-update-bare-Var-referenc.patch)
download | inline diff:
From 482ecc12363230b96ccf4fa39fd2fcc2b77b486a Mon Sep 17 00:00:00 2001
From: "Andrei V. Lepikhov" <lepihov@gmail.com>
Date: Wed, 18 Mar 2026 14:23:46 +0100
Subject: [PATCH v2] Fix self-join removal to update bare Var references in
join clauses
Self-join removal failed to update Var nodes when the join clause was a
bare Var (e.g., ON t1.bool_col) rather than an expression containing
Vars. ChangeVarNodesWalkExpression() used expression_tree_walker(),
which descends into child nodes but does not process the top-level node
itself. When a bare Var referencing the removed relation appeared as
the clause, its varno was left unchanged, leading to "no relation entry
for relid N" errors.
Fix by calling ChangeVarNodes_walker() directly instead of
expression_tree_walker(), so the top-level node is also processed.
Bug: #19435
Reported-by: Hang Ammmkilo <ammmkilo@163.com>
Author: Andrei Lepikhov <lepihov@gmail.com>
Co-authored-by: Tender Wang <tndrwang@gmail.com>
Co-authored-by: Alexander Korotkov <aekorotkov@gmail.com>
Reviewed-by: Kirill Reshke <reshkekirill@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/19435-3cc1a87f291129f1%40postgresql.org
---
src/backend/rewrite/rewriteManip.c | 4 +---
src/test/regress/expected/join.out | 16 ++++++++++++++++
src/test/regress/sql/join.sql | 6 ++++++
3 files changed, 23 insertions(+), 3 deletions(-)
diff --git a/src/backend/rewrite/rewriteManip.c b/src/backend/rewrite/rewriteManip.c
index 5282f60e531..7249ffbfb36 100644
--- a/src/backend/rewrite/rewriteManip.c
+++ b/src/backend/rewrite/rewriteManip.c
@@ -744,9 +744,7 @@ ChangeVarNodes(Node *node, int rt_index, int new_index, int sublevels_up)
bool
ChangeVarNodesWalkExpression(Node *node, ChangeVarNodes_context *context)
{
- return expression_tree_walker(node,
- ChangeVarNodes_walker,
- (void *) context);
+ return ChangeVarNodes_walker(node, context);
}
/*
diff --git a/src/test/regress/expected/join.out b/src/test/regress/expected/join.out
index ea3dabff77c..dc5b798c336 100644
--- a/src/test/regress/expected/join.out
+++ b/src/test/regress/expected/join.out
@@ -8091,6 +8091,22 @@ WHERE q0.a = 1;
-> Seq Scan on sj n1
(7 rows)
+-- Do not forget to replace relid in bare Var join clause (bug #19435)
+ALTER TABLE sl ADD COLUMN bool_col boolean;
+EXPLAIN (COSTS OFF)
+SELECT 1 AS c1 FROM sl sl1 LEFT JOIN (sl AS sl2 NATURAL JOIN sl AS sl3)
+ ON sl2.bool_col LEFT JOIN sl AS sl4 ON sl2.bool_col;
+ QUERY PLAN
+-------------------------------------------------------------------------------------------------------------------------
+ Nested Loop Left Join
+ -> Seq Scan on sl sl1
+ -> Nested Loop Left Join
+ Join Filter: sl3.bool_col
+ -> Seq Scan on sl sl3
+ Filter: (bool_col AND (a IS NOT NULL) AND (b IS NOT NULL) AND (c IS NOT NULL) AND (bool_col IS NOT NULL))
+ -> Seq Scan on sl sl4
+(7 rows)
+
-- Check optimization disabling if it will violate special join conditions.
-- Two identical joined relations satisfies self join removal conditions but
-- stay in different special join infos.
diff --git a/src/test/regress/sql/join.sql b/src/test/regress/sql/join.sql
index ad90c326c00..f5631bf97ff 100644
--- a/src/test/regress/sql/join.sql
+++ b/src/test/regress/sql/join.sql
@@ -3156,6 +3156,12 @@ SELECT * FROM
(SELECT n2.a FROM sj n1, sj n2 WHERE n1.a <> n2.a) q0, sl
WHERE q0.a = 1;
+-- Do not forget to replace relid in bare Var join clause (bug #19435)
+ALTER TABLE sl ADD COLUMN bool_col boolean;
+EXPLAIN (COSTS OFF)
+SELECT 1 AS c1 FROM sl sl1 LEFT JOIN (sl AS sl2 NATURAL JOIN sl AS sl3)
+ ON sl2.bool_col LEFT JOIN sl AS sl4 ON sl2.bool_col;
+
-- Check optimization disabling if it will violate special join conditions.
-- Two identical joined relations satisfies self join removal conditions but
-- stay in different special join infos.
--
2.39.5 (Apple Git-154)
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Subject: Re: BUG #19435: Error: "No relation entry for relid 2" Triggered by Complex Join with Self-Referencing Tables
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