Horton

Re: pg_upgrade and logical replication

Michael Paquier <michael@paquier.xyz>

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From: Michael Paquier <michael@paquier.xyz>
To: Amit Kapila <amit.kapila16@gmail.com>
Cc: vignesh C <vignesh21@gmail.com>, "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>, Julien Rouhaud <rjuju123@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2023-09-20T23:08:59Z
Lists: pgsql-hackers 
On Wed, Sep 20, 2023 at 04:54:36PM +0530, Amit Kapila wrote:
> Also, the patch seems to be allowing subscription relations from PG
> >=10 to be migrated but how will that work if the corresponding
> publisher is also upgraded without slots? Won't the corresponding
> workers start failing as soon as you restart the upgrade server? Do we
> need to document the steps for users?

Hmm?  How is that related to the upgrade of the subscribers?  And how
is that different from the case where a subscriber tries to connect
back to a publisher where a slot has been dropped?  There is no need
of pg_upgrade to reach such a state:
ERROR:  could not start WAL streaming: ERROR:  replication slot "popo" does not exist
--
Michael

Commits

  1. pg_upgrade: Retrieve subscription count more efficiently.

  2. Fix random failure in 004_subscription.

  3. Fix 004_subscription.pl to allow its usage in --link mode.

  4. Allow upgrades to preserve the full subscription's state.

  5. Prevent startup of logical replication launcher during pg_upgrade