Horton

Re: pg_upgrade and logical replication

vignesh C <vignesh21@gmail.com>

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From: vignesh C <vignesh21@gmail.com>
To: Michael Paquier <michael@paquier.xyz>
Cc: "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>, Julien Rouhaud <rjuju123@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Amit Kapila <amit.kapila16@gmail.com>
Date: 2023-09-19T13:44:49Z
Lists: pgsql-hackers

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On Tue, 19 Sept 2023 at 11:49, Michael Paquier <michael@paquier.xyz> wrote:
>
> On Fri, Sep 15, 2023 at 04:51:57PM +0530, vignesh C wrote:
> > Another approach to solve this as suggested by one of my colleague
> > Hou-san would be to set max_logical_replication_workers = 0 while
> > upgrading. I will evaluate this and update the next version of patch
> > accordingly.
>
> In the context of an upgrade, any node started is isolated with its
> own port and a custom unix domain directory with connections allowed
> only through this one.
>
> Saying that, I don't see why forcing max_logical_replication_workers
> to be 0 would be necessarily a bad thing to prevent unnecessary
> activity on the backend.  This should be a separate patch built on
> top of the main one, IMO.

Here is a patch to set max_logical_replication_workers as 0 while the
server is started to prevent the launcher from being started. Since
this configuration is present from v10, no need for any version check.
I have done upgrade tests for v10-master, v11-master, ... v16-master
and found it to be working fine.

Regards,
Vignesh

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