Feedback-ID: ie3de48e3:Fastmail
Date: Fri, 18 Sep 2026 13:54:46 +0200
From: =?utf-8?Q?=C3=81lvaro?= Herrera <alvherre@kurilemu.de>
To: Dmitry Dolgov <9erthalion6@gmail.com>
Cc: Mihail Nikalayeu <mihailnikalayeu@gmail.com>,
	Michael Paquier <michael@paquier.xyz>,
 Zsolt Parragi <zsolt.parragi@percona.com>,
	pgsql-hackers@lists.postgresql.org
Subject: Re: Routed ON CONFLICT inserts broken by partition-local deferrable
 unique constraints in 19 and master
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On 2026-Sep-16, Dmitry Dolgov wrote:

> +	/* number of key attributes must match */
> +	if (indexForm1->indnkeyatts != indexForm2->indnkeyatts)
> +		return false;
> 
> I see that it was like this in the original commit, but isn't it too
> restrictive regarding the goal stated in the function comment? If say
> there are two unique indexes on columns (a), and (a, b), they have the
> same understanding of what tuples will conflict, but the latter one will
> not be used as an arbiter index. To be fair, I don't see how this may
> become problem in practice, but still.

I'm not sure I understand this concern.  Do you want to elaborate?

This functionality is there to support having two copies of "the same"
index during REINDEX CONCURRENTLY, and of course the second copy is
going to be identical in definition to the first one.

Maybe you want to propose a different name or a different comment for
this new function?

-- 
Álvaro Herrera         PostgreSQL Developer  —  https://www.EnterpriseDB.com/