Feedback-ID: i0fe9450f:Fastmail
Date: Thu, 9 Oct 2025 13:37:16 +0900
From: Michael Paquier <michael@paquier.xyz>
To: "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>
Cc: 'Peter Smith' <smithpb2250@gmail.com>,
	"Aya Iwata (Fujitsu)" <iwata.aya@fujitsu.com>,
	pgsql-hackers <pgsql-hackers@postgresql.org>
Subject: Re: [PROPOSAL] Termination of Background Workers for ALTER/DROP
 DATABASE
Message-ID: <aOc7_JGErxvqBLMP@paquier.xyz>
References: 
 <OS7PR01MB119648846BA926C096CE016B6EAE3A@OS7PR01MB11964.jpnprd01.prod.outlook.com>
 <CAHut+Pt4Tn1bQYCsYeUt_gtcSB-KOTtRB70SLghkpsjfKGsm7w@mail.gmail.com>
 <OS7PR01MB119642CFE4F4DCF7FBBD040BBEAE0A@OS7PR01MB11964.jpnprd01.prod.outlook.com>
 <CAHut+Pu-nxNice547eGEW2O3hdRcFbPYWF4HiqktZO19X3Ah-g@mail.gmail.com>
 <OS7PR01MB11964628A74081DFCA442CBADEAE1A@OS7PR01MB11964.jpnprd01.prod.outlook.com>
 <CAHut+PuuOKKW2oDT0Z8q+UXsiteS67j6G6075FC3aAxeR0cxHQ@mail.gmail.com>
 <OSCPR01MB14966FC50CFB457938763AE09F5EEA@OSCPR01MB14966.jpnprd01.prod.outlook.com>
 <OSCPR01MB14966B98E5119EBB261024ED2F5EEA@OSCPR01MB14966.jpnprd01.prod.outlook.com>
 <aOctHMnSZcREh0BR@paquier.xyz>
 <OSCPR01MB1496614832F8014EC16FB78D2F5EEA@OSCPR01MB14966.jpnprd01.prod.outlook.com>
MIME-Version: 1.0
Content-Type: multipart/signed; micalg=pgp-sha512;
	protocol="application/pgp-signature"; boundary="w6TqxXLXMwrsGCUT"
Content-Disposition: inline
In-Reply-To: 
 <OSCPR01MB1496614832F8014EC16FB78D2F5EEA@OSCPR01MB14966.jpnprd01.prod.outlook.com>
Archived-At: 
 <https://www.postgresql.org/message-id/aOc7_JGErxvqBLMP%40paquier.xyz>
Precedence: bulk


--w6TqxXLXMwrsGCUT
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline

On Thu, Oct 09, 2025 at 04:00:24AM +0000, Hayato Kuroda (Fujitsu) wrote:
> Based on that, I imagined that we could launch a bgworker and create
> another database by using template. Or is it already handled?

Oh, I was not following you here.  Yes, we should have something with
a bgworker connected to a source and make sure that it disconnects
when create a new database with this source as template.

However, could there be more to consider here?  Contrary to DROP
DATABASE, where we require the drop to be done by the owner of the
database (or a superuser), CREATE DATABASE has less requirements: it
is fine for a role to create a database if they have the CREATEDB
rights.  If we allow bgworkers to be cancelled when the database they
are connected to is used as a source, that may be disruptive, so we
had better document precisely the behavior of the flag and what users
should expect from it when set.  We are already killing autovacuum
workers when they are connected to a database used as a source anyway
(since 4abd7b49f1e9 from 2008), so I am worrying for nothing and it is
actually better to apply the same rule across the board.  Let's just
document very clearly how the bgworker will react when the cancel flag
is set in all these cases.
--
Michael

--w6TqxXLXMwrsGCUT
Content-Type: application/pgp-signature; name="signature.asc"

-----BEGIN PGP SIGNATURE-----
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=IqSc
-----END PGP SIGNATURE-----

--w6TqxXLXMwrsGCUT--