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From: Laurenz Albe <[email protected]>
To: Hüseyin Demir <[email protected]>
Cc: [email protected]
Subject: Re: BUG #19393: pg_upgrade fails with duplicate key violation when CHECK constraint named *_not_null exists
Date: Mon, 09 Feb 2026 12:01:27 +0100
Message-ID: <[email protected]> (raw)
In-Reply-To: <CAB5wL7aPZ_GPEZkMtkcnQjmv_uMxjJZmsrCf9onDCJGL_NUtTg@mail.gmail.com>
References: <[email protected]>
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On Mon, 2026-02-09 at 07:24 +0100, Hüseyin Demir wrote:
> Thanks for the patch and LGTM for PostgreSQL 18.

Thanks for checking!

> I tried to create following table on PG18
> 
> benchmark=# CREATE TABLE two_not_null_constraints (
>      col integer NOT NULL,
>      CONSTRAINT two_not_null_constraints_col_not_null CHECK (col IS NOT NULL)
>   );
> ERROR:  duplicate key value violates unique constraint "pg_constraint_conrelid_contypid_conname_index"
> DETAIL:  Key (conrelid, contypid, conname)=(16385, 0, two_not_null_constraints_col_not_null) already exists.
> 
> In PG17 I was able to create the table.

Yes, because what causes your problemm is a new feature in v18.

> One question during the tests should we confirm the output of pg_constraint table ?
> It would make sense during the tests but the current test is also good to proceed.

I would prefer not to, but I don't have a strong opinion about it.
Which name PostgreSQL chooses for the generated NOT NULL constraint
is not important, as long as it doesn't conflict with the existing name.

Yours,
Laurenz Albe

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