Re: Wrong results from an antijoin

From: Richard Guo <guofenglinux(at)gmail(dot)com>
To: Pg Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: Wrong results from an antijoin
Date: 2026-10-11 12:41:03
Message-ID: CAMbWs4-nAQAyGeEKtcePaC8PPE3-Jfwr5T-9HmDEQseUfrsKSQ@mail.gmail.com
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On Fri, Oct 9, 2026 at 12:21 PM Richard Guo <guofenglinux(at)gmail(dot)com> wrote:
> So I think a more principled way is to give the antijoin a relid, just
> like an antijoin reduced from a left join has, so that we can leverage
> the well-established outer-join relid machinery to keep quals above
> it.

> I'm writing a patch along these lines, but I'd like to hear what
> others think before going too far.

Here is the patch I end up with.

Of the join types that IS_OUTER_JOIN() covers, ANTI was the only one
that could lack a relid, and only when it came from a sublink. Now
every outer join has one, so we no longer need the "if (j->rtindex !=
0)" checks in the code.

Any thoughts?

- Richard

Attachment Content-Type Size
v1-0001-Give-antijoins-made-from-sublinks-a-relid.patch application/octet-stream 12.0 KB

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