| From: | Tender Wang <tndrwang(at)gmail(dot)com> |
|---|---|
| To: | SATYANARAYANA NARLAPURAM <satyanarlapuram(at)gmail(dot)com> |
| Cc: | PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, Richard Guo <guofenglinux(at)gmail(dot)com> |
| Subject: | Re: Bug: var_is_nonnullable() gives wrong results for old/new in RETURNING |
| Date: | 2026-04-10 01:29:48 |
| Message-ID: | CAHewXN=9mf6NCeHE=7jUVhM_Ur=oW8R7hgfQwcvyWCSLC8VERw@mail.gmail.com |
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| Lists: | pgsql-hackers |
SATYANARAYANA NARLAPURAM <satyanarlapuram(at)gmail(dot)com> 于2026年4月10日周五 02:43写道：
>
> Hi hackers,
>
> It appears the optimizer incorrectly simplifies old.<col> IS NULL to FALSE in RETURNING clauses when the underlying column has a NOT NULL constraint.
>
> The issue is that var_is_nonnullable() in clauses.c doesn't check Var.varreturningtype. It sees a NOT NULL column and concludes the Var can never be NULL.
> But this assumption is wrong for old.* and new.* references. Because the old tuple doesn't exist on INSERT, and the new tuple doesn't exist on DELETE
> I am not super familiar with this area, so I attempted to fix this as in the patch attached.
Yes, the current var_is_nonnullable() ignores this case. The
attached patch seems ok to me.
Add Richard to the cc list. He may know more about this.
--
Thanks,
Tender Wang
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