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help / color / mirror / Atom feedFrom: Tender Wang <tndrwang@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Alexander Korotkov <aekorotkov@gmail.com>
Cc: Andrei Lepikhov <lepihov@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: Sun, 22 Mar 2026 13:15:56 +0800
Message-ID: <CAHewXN=Kn-+-3KA=DLoGQyBkgf6JVwLa8cvgLs8yBvdaX7gYFw@mail.gmail.com> (raw)
In-Reply-To: <1777986.1774038373@sss.pgh.pa.us>
References: <19435-3cc1a87f291129f1@postgresql.org>
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<1777986.1774038373@sss.pgh.pa.us>
Hi Tom,
Tom Lane <tgl@sss.pgh.pa.us> 于2026年3月21日周六 04:26写道：
>
> I wrote:
> > At the very least we need to add comments, but I wonder if we
> > don't actually need an Assert that ChangeVarNodesWalkExpression
> > is not invoked directly on a Query. It would have done the
> > right thing before this patch, but now it won't. That's an
> > okay tradeoff for fixing the bare-Var case, but not documenting
> > what you did is not okay.
>
> After further contemplation I've decided that an Assert would be
> wrong, because it's not impossible that a callback would want
> to invoke this on a sub-Query --- for instance, if it wanted to
> short-circuit ChangeVarNodes's processing of a SubLink node,
> it would need to do that. The key point is that if we do see a
> Query node here, we will treat it as a sub-query not a top-level
> query, which also justifies skipping the work that
> ChangeVarNodesExtended does on a top-level Query. So we just
> need a comment explaining that. I'm thinking about the attached.
>
> (BTW, by this reasoning the previous implementation of
> ChangeVarNodesWalkExpression was doubly wrong, since it would
> have done the wrong thing at a Query node as well as a Var node.)
Thanks for pointing this out. The attached looks good to me.
Do you have some advice about that the same qual is present
twice in the plan, see [1].
Should we do something in restrict_infos_logically_equal().
Please take a look.
--
Thanks,
Tender Wang
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Subject: Re: BUG #19435: Error: "No relation entry for relid 2" Triggered by Complex Join with Self-Referencing Tables
In-Reply-To: <CAHewXN=Kn-+-3KA=DLoGQyBkgf6JVwLa8cvgLs8yBvdaX7gYFw@mail.gmail.com>
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