Feedback-ID: i0fe9450f:Fastmail
Date: Wed, 12 Apr 2023 09:31:51 +0900
From: Michael Paquier <michael@paquier.xyz>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Richard Guo <guofenglinux@gmail.com>,
	Alvaro Herrera <alvherre@alvh.no-ip.org>,
	PostgreSQL mailing lists <pgsql-bugs@lists.postgresql.org>
Subject: Re: ERROR: no NOT NULL constraint found to drop
Message-ID: <ZDX79xxrpmbDo5vx@paquier.xyz>
References: 
 <CAMbWs48astPDb3K+L89wb8Yju0jM_Czm8svmU=Uzd+WM61Cr6Q@mail.gmail.com>
 <ZDPA8BJ4YgZymdoY@paquier.xyz>
 <4031605.1681134419@sss.pgh.pa.us>
MIME-Version: 1.0
Content-Type: multipart/signed; micalg=pgp-sha512;
	protocol="application/pgp-signature"; boundary="6pUwFNPFCi1SLC68"
Content-Disposition: inline
In-Reply-To: <4031605.1681134419@sss.pgh.pa.us>
Archived-At: 
 <https://www.postgresql.org/message-id/ZDX79xxrpmbDo5vx%40paquier.xyz>
Precedence: bulk


--6pUwFNPFCi1SLC68
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline

On Mon, Apr 10, 2023 at 09:46:59AM -0400, Tom Lane wrote:
> It's still good to know about it for next time.  The issue I guess is
> that LIKE with no options propagates column attnotnull bits, but not
> constraints, so we now have an inconsistency: t2.c has attnotnull set
> but there is nothing in pg_constraint to justify it.  It seems to me
> we're going to have to think about what we want to happen in this
> case.  In a green field we'd probably not propagate NOT NULL unless
> told to copy constraints ... but is it okay to break functional
> compatibility with the old behavior?

I am not sure about that, TBH, though I would tend to not break
compatibility just for the sake of breaking it.  Anyway, shouldn't we
have a test that does a DROP NOT NULL after a LIKE copies it?  At
least, we'll be able to track that.
--
Michael

--6pUwFNPFCi1SLC68
Content-Type: application/pgp-signature; name="signature.asc"

-----BEGIN PGP SIGNATURE-----
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=FI/n
-----END PGP SIGNATURE-----

--6pUwFNPFCi1SLC68--