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help / color / mirror / Atom feedFrom: Alexander Korotkov <aekorotkov@gmail.com>
To: Tender Wang <tndrwang@gmail.com>
Cc: Kirill Reshke <reshkekirill@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: Wed, 18 Mar 2026 10:40:17 +0200
Message-ID: <CAPpHfducqLJ=o3LkoPKGfZJVQuuei+P=2oUF6hX6rzHTZSxoyA@mail.gmail.com> (raw)
In-Reply-To: <CAHewXNm5OOREJ8wZ1cLJdQz7O1aQ0E1RBB55S6O138K8vBdc9g@mail.gmail.com>
References: <19435-3cc1a87f291129f1@postgresql.org>
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Hi, Tender!
On Wed, Mar 18, 2026 at 7:44 AM Tender Wang <tndrwang@gmail.com> wrote:
>
> Tender Wang <tndrwang@gmail.com> 于2026年3月18日周三 09:12写道：
> >
> > Alexander Korotkov <aekorotkov@gmail.com> 于2026年3月18日周三 01:46写道：
> > >
> > > On Tue, Mar 17, 2026 at 3:30 PM Tender Wang <tndrwang@gmail.com> wrote:
> > > > Kirill Reshke <reshkekirill@gmail.com> 于2026年3月17日周二 21:24写道：
> > > > >
> > > > > On Tue, 17 Mar 2026 at 18:20, Tender Wang <tndrwang@gmail.com> wrote:
> > > > > Yes, it looks like your analysis is valid. Will you share a patch for
> > > > > updating `clause` ?
> > > > >
> > > > Sorry, it's already the middle of the night here, so I'm afraid I
> > > > don't have much time to work on this right now.
> > >
> > > Thank you for your research. I've written a simple draft patch. It
> > > fixes the reported case, but I doubt it is correct in general. I'll
> > > continue the investigation.
> > I tried the above fix, no error again. But I got a plan like this:
> > QUERY PLAN
> > -------------------------------------------------------------------------------------------
> > Nested Loop Left Join (cost=0.00..115164616.71 rows=7458350250 width=4)
> > -> Seq Scan on pg_table_a tom3 (cost=0.00..34.70 rows=2470 width=0)
> > -> Materialize (cost=0.00..99509.82 rows=3019575 width=0)
> > -> Nested Loop Left Join (cost=0.00..75564.95 rows=3019575 width=0)
> > Join Filter: tom2.col_bool
> > -> Seq Scan on pg_table_a tom2 (cost=0.00..34.70
> > rows=2445 width=5)
> > Filter: ((col_bool IS NOT NULL) AND (col_bool IS NOT NULL))
> > -> Materialize (cost=0.00..47.05 rows=2470 width=0)
> > -> Seq Scan on pg_table_a tom0
> > (cost=0.00..34.70 rows=2470 width=0)
> > (9 rows)
> >
> > Filter: ((col_bool IS NOT NULL) AND (col_bool IS NOT NULL))
> > This makes me unhappy.
> > Your patch gets the same plan.
> >
> In replace_relid_callback(), we add NullTest to rinfo, but it is not a
> logical equal check by restrict_infos_logically_equal().
> I think for baserestrictinfo, we can just use rinfo->clause, no need
> to check the equality of RestrictInfo.
>
> I tried this way, the plan looks as follows:
> QUERY PLAN
> -------------------------------------------------------------------------------------------
> Nested Loop Left Join (cost=0.00..115776846.35 rows=7498006100 width=4)
> -> Seq Scan on pg_table_a tom3 (cost=0.00..34.70 rows=2470 width=0)
> -> Materialize (cost=0.00..100038.47 rows=3035630 width=0)
> -> Nested Loop Left Join (cost=0.00..75966.32 rows=3035630 width=0)
> Join Filter: tom2.col_bool
> -> Seq Scan on pg_table_a tom2 (cost=0.00..34.70
> rows=2458 width=5)
> Filter: (col_bool IS NOT NULL)
> -> Materialize (cost=0.00..47.05 rows=2470 width=0)
> -> Seq Scan on pg_table_a tom0
> (cost=0.00..34.70 rows=2470 width=0)
> (9 rows)
>
> No redundant filter anymore.
>
> Please see the attached patch.
What about being more generic and call ChangeVarNodes_walker() for the
node in ChangeVarNodesWalkExpression()? It also works with out case
and avoids code duplication.
Changes in restrict_infos_logically_equal() makes me a bit uneasy. I
see, restictinfo's are different by their outer_relids. Why
outer_relids doesn't matter when required_relids is singleton? More
general when do outer_relids matter for add_non_redundant_clauses() if
we're putting restictinfo's into a single list anyway?
------
Regards,
Alexander Korotkov
Supabase
Attachments:
[application/octet-stream] 0001-Fix-sje-bug-v2.patch (1.3K, 2-0001-Fix-sje-bug-v2.patch)
download | inline diff:
diff --git a/src/backend/optimizer/plan/analyzejoins.c b/src/backend/optimizer/plan/analyzejoins.c
index 12e9ed0d0c7..4b9b5d563f6 100644
--- a/src/backend/optimizer/plan/analyzejoins.c
+++ b/src/backend/optimizer/plan/analyzejoins.c
@@ -1635,9 +1635,14 @@ restrict_infos_logically_equal(RestrictInfo *a, RestrictInfo *b)
int saved_rinfo_serial = a->rinfo_serial;
bool result;
- a->rinfo_serial = b->rinfo_serial;
- result = equal(a, b);
- a->rinfo_serial = saved_rinfo_serial;
+ if (bms_membership(a->required_relids) == BMS_SINGLETON)
+ result = equal(a->clause, b->clause);
+ else
+ {
+ a->rinfo_serial = b->rinfo_serial;
+ result = equal(a, b);
+ a->rinfo_serial = saved_rinfo_serial;
+ }
return result;
}
diff --git a/src/backend/rewrite/rewriteManip.c b/src/backend/rewrite/rewriteManip.c
index fe89754a73c..2ad663c952a 100644
--- a/src/backend/rewrite/rewriteManip.c
+++ b/src/backend/rewrite/rewriteManip.c
@@ -744,6 +744,12 @@ ChangeVarNodes(Node *node, int rt_index, int new_index, int sublevels_up)
bool
ChangeVarNodesWalkExpression(Node *node, ChangeVarNodes_context *context)
{
+ if (node == NULL)
+ return false;
+
+ if (ChangeVarNodes_walker(node, context))
+ return true;
+
return expression_tree_walker(node,
ChangeVarNodes_walker,
(void *) context);
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To: pgsql-bugs@postgresql.org
Cc: aekorotkov@gmail.com, tndrwang@gmail.com, reshkekirill@gmail.com, masao.fujii@gmail.com, ammmkilo@163.com, pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #19435: Error: "No relation entry for relid 2" Triggered by Complex Join with Self-Referencing Tables
In-Reply-To: <CAPpHfducqLJ=o3LkoPKGfZJVQuuei+P=2oUF6hX6rzHTZSxoyA@mail.gmail.com>
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