Date: Tue, 13 Feb 2024 15:05:14 -0600
From: Justin Pryzby <pryzby@telsasoft.com>
To: Amit Kapila <amit.kapila16@gmail.com>
Cc: vignesh C <vignesh21@gmail.com>,
	Masahiko Sawada <sawada.mshk@gmail.com>,
	Michael Paquier <michael@paquier.xyz>,
	Peter Smith <smithpb2250@gmail.com>,
	"Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>,
	Julien Rouhaud <rjuju123@gmail.com>,
	pgsql-hackers@lists.postgresql.org
Subject: Re: pg_upgrade and logical replication
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On Tue, Jan 02, 2024 at 03:58:25PM +0530, Amit Kapila wrote:
> Pushed.

pg_upgrade/t/004_subscription.pl says

|my $mode = $ENV{PG_TEST_PG_UPGRADE_MODE} || '--copy';

..but I think maybe it should not.

When you try to use --link, it fails:
https://cirrus-ci.com/task/4669494061170688

|Adding ".old" suffix to old global/pg_control                 ok
|
|If you want to start the old cluster, you will need to remove
|the ".old" suffix from /tmp/cirrus-ci-build/build/testrun/pg_upgrade/004_subscription/data/t_004_subscription_old_sub_data/pgdata/global/pg_control.old.
|Because "link" mode was used, the old cluster cannot be safely
|started once the new cluster has been started.
|...
|
|postgres: could not find the database system
|Expected to find it in the directory "/tmp/cirrus-ci-build/build/testrun/pg_upgrade/004_subscription/data/t_004_subscription_old_sub_data/pgdata",
|but could not open file "/tmp/cirrus-ci-build/build/testrun/pg_upgrade/004_subscription/data/t_004_subscription_old_sub_data/pgdata/global/pg_control": No such file or directory
|# No postmaster PID for node "old_sub"
|[19:36:01.396](0.250s) Bail out!  pg_ctl start failed

You could rename pg_control.old to avoid that immediate error, but that doesn't
address the essential issue that "the old cluster cannot be safely started once
the new cluster has been started."

-- 
Justin