MIME-Version: 1.0
References: <19435-3cc1a87f291129f1@postgresql.org> <CAHGQGwEEHFnH8DsZbwxdZeiHozm2LCRTLSgL8Qn=5MoN4450ZA@mail.gmail.com>
 <CAPpHfdsDQhDqvqi+-UxvyYRP72ASkdWzCn43e2Hj6WsY15opvA@mail.gmail.com>
 <CAHewXNmU3E0oXLgvoOtXw7kfTiAZsKu8La_hQ=pyScgxvP45iw@mail.gmail.com>
 <CAHewXN=LjuWz3PcyhjdbJAyo+Zs9MisPDRYnSZBUy4PMeKi+zA@mail.gmail.com>
 <CALdSSPj1kTTQvmV3H3HMf5P3um8ybxoH3DaTPm+XgdYAur1Q4A@mail.gmail.com>
 <CAHewXNndByMu3S+_h4LLDkXA5qrO1s=s-CE8HqUtc9vTA9yrjg@mail.gmail.com>
 <CAPpHfdv6gzSTXHJxYSgB8sULadXM4wvhgoQODaOxYCJfagKNPw@mail.gmail.com>
 <CAHewXN=7kDJjUcgEm+6qhaKOXuqzvhRqAAKdafNCRgn0yH7BGg@mail.gmail.com> <CAHewXNm5OOREJ8wZ1cLJdQz7O1aQ0E1RBB55S6O138K8vBdc9g@mail.gmail.com>
In-Reply-To: <CAHewXNm5OOREJ8wZ1cLJdQz7O1aQ0E1RBB55S6O138K8vBdc9g@mail.gmail.com>
From: Kirill Reshke <reshkekirill@gmail.com>
Date: Wed, 18 Mar 2026 10:56:55 +0500
Message-ID: <CALdSSPiL5pFNvvh9HyDQ7syzF6jOvQirC5nQWaC_n1_NQy5-PQ@mail.gmail.com>
Subject: Re: BUG #19435: Error: "No relation entry for relid 2" Triggered by
 Complex Join with Self-Referencing Tables
To: Tender Wang <tndrwang@gmail.com>
Cc: Alexander Korotkov <aekorotkov@gmail.com>, Fujii Masao <masao.fujii@gmail.com>, ammmkilo@163.com, 
	pgsql-bugs@lists.postgresql.org
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Archived-At: <https://www.postgresql.org/message-id/CALdSSPiL5pFNvvh9HyDQ7syzF6jOvQirC5nQWaC_n1_NQy5-PQ%40mail.gmail.com>
Precedence: bulk

On Wed, 18 Mar 2026 at 10:44, Tender Wang <tndrwang@gmail.com> wrote:
>
> Tender Wang <tndrwang@gmail.com> =E4=BA=8E2026=E5=B9=B43=E6=9C=8818=E6=97=
=A5=E5=91=A8=E4=B8=89 09:12=E5=86=99=E9=81=93=EF=BC=9A
> >
> > Alexander Korotkov <aekorotkov@gmail.com> =E4=BA=8E2026=E5=B9=B43=E6=9C=
=8818=E6=97=A5=E5=91=A8=E4=B8=89 01:46=E5=86=99=E9=81=93=EF=BC=9A
> > >
> > > On Tue, Mar 17, 2026 at 3:30=E2=80=AFPM Tender Wang <tndrwang@gmail.c=
om> wrote:
> > > > Kirill Reshke <reshkekirill@gmail.com> =E4=BA=8E2026=E5=B9=B43=E6=
=9C=8817=E6=97=A5=E5=91=A8=E4=BA=8C 21:24=E5=86=99=E9=81=93=EF=BC=9A
> > > > >
> > > > > On Tue, 17 Mar 2026 at 18:20, Tender Wang <tndrwang@gmail.com> wr=
ote:
> > > > > 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=3D0.00..115164616.71 rows=3D7458350250 wi=
dth=3D4)
> >    ->  Seq Scan on pg_table_a tom3  (cost=3D0.00..34.70 rows=3D2470 wid=
th=3D0)
> >    ->  Materialize  (cost=3D0.00..99509.82 rows=3D3019575 width=3D0)
> >          ->  Nested Loop Left Join  (cost=3D0.00..75564.95 rows=3D30195=
75 width=3D0)
> >                Join Filter: tom2.col_bool
> >                ->  Seq Scan on pg_table_a tom2  (cost=3D0.00..34.70
> > rows=3D2445 width=3D5)
> >                      Filter: ((col_bool IS NOT NULL) AND (col_bool IS N=
OT NULL))
> >                ->  Materialize  (cost=3D0.00..47.05 rows=3D2470 width=
=3D0)
> >                      ->  Seq Scan on pg_table_a tom0
> > (cost=3D0.00..34.70 rows=3D2470 width=3D0)
> > (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=3D0.00..115776846.35 rows=3D7498006100 widt=
h=3D4)
>    ->  Seq Scan on pg_table_a tom3  (cost=3D0.00..34.70 rows=3D2470 width=
=3D0)
>    ->  Materialize  (cost=3D0.00..100038.47 rows=3D3035630 width=3D0)
>          ->  Nested Loop Left Join  (cost=3D0.00..75966.32 rows=3D3035630=
 width=3D0)
>                Join Filter: tom2.col_bool
>                ->  Seq Scan on pg_table_a tom2  (cost=3D0.00..34.70
> rows=3D2458 width=3D5)
>                      Filter: (col_bool IS NOT NULL)
>                ->  Materialize  (cost=3D0.00..47.05 rows=3D2470 width=3D0=
)
>                      ->  Seq Scan on pg_table_a tom0
> (cost=3D0.00..34.70 rows=3D2470 width=3D0)
> (9 rows)
>
> No redundant filter anymore.
>
> Please see the attached patch.
>
> --
> Thanks,
> Tender Wang

Hi!
Your patch looks solid. ChangeVarNodesWalkExpression looks like a
generic rewriter utility function, so I was wondering why we never got
complaints about bugs related it. But this functions is reachable only
when SJE optimisation is allowed, so looks like this explains the
issue.


--=20
Best regards,
Kirill Reshke