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From: Amul Sul <sulamul@gmail.com>
Date: Mon, 20 Jan 2025 12:11:18 +0530
Message-ID: <CAAJ_b96gbP0CU+VaXC_cPOB0zDXd+ygOac_9r8PVPej8gA+cYA@mail.gmail.com>
Subject: Re: Bug in detaching a partition with a foreign key.
To: Sami Imseih <samimseih@gmail.com>
Cc: PostgreSQL-development <pgsql-hackers@postgresql.org>
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On Sat, Jan 18, 2025 at 2:14=E2=80=AFAM Sami Imseih <samimseih@gmail.com> w=
rote:
>
> This is a bug indeed. I tried your patch, but it ends up in a seg fault.
>
> [...]
> If the relation on the parent and child constraint match, that
> tells us we don't have inheritance.
> So, I am thinking we should add another condition for checking
> if a foreign key is inherited by checking if the parent constraint
> relation is different from the child constraint relation.
>
> I am attaching an unpolished patch ( we need test coverage as well ) that
> implements  the above. All tests pass with this patch.

Thanks for confirming the bug. TBH, I haven't had a chance to look into the
issue in detail yet, but my understanding of the detach operation is that i=
t
should cut the link between the parent constraint and the constraint on
the partition being detached. The trial patch I posted was meant to prevent
cutting the link between the partition's constraint and the constraint that
inherits it.  Your patch seems to achieve the same, AFAIUC, but I'm not sur=
e I
like the way it's doing, nor the trial patch I posted. A crash is certainly
possible with that patch, but it would be helpful if you could provide more
context -- such as crash detail and/or a test case.

Regards,
Amul