From: Tom Lane <tgl@sss.pgh.pa.us>
To: Alvaro Herrera <alvherre@alvh.no-ip.org>
cc: Jehan-Guillaume de Rorthais <jgdr@dalibo.com>,
        pgsql-hackers <pgsql-hackers@postgresql.org>
Subject: Re: [BUG] parenting a PK constraint to a self-FK one (Was: Self FK
 oddity when attaching a partition)
In-reply-to: <20220823163006.smdpovyl4dhcakvr@alvherre.pgsql>
References: <20220823163006.smdpovyl4dhcakvr@alvherre.pgsql>
Comments: In-reply-to Alvaro Herrera <alvherre@alvh.no-ip.org>
	message dated "Tue, 23 Aug 2022 18:30:06 +0200"
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Date: Tue, 23 Aug 2022 14:00:13 -0400
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Alvaro Herrera <alvherre@alvh.no-ip.org> writes:
> If this is OK, we should make this API quirkiness very explicit in the
> comments, so the patch needs to be a few lines larger in order to be
> committable.  Also, perhaps the check should be that contype equals
> either primary or unique, rather than it doesn't equal foreign.

Yeah.  See lsyscache.c's get_constraint_index(), as well as commit
641f3dffc which fixed a mighty similar-seeming bug.  One question
that precedent raises is whether to also include CONSTRAINT_EXCLUSION.
But in any case a positive test for the constraint types to allow
seems best.

			regards, tom lane