Re: A recent message added to pg_upgade

On Fri, Nov 10, 2023 at 7:50 AM Michael Paquier <michael@paquier.xyz> wrote:
>
> On Thu, Nov 09, 2023 at 04:52:32PM +0900, Michael Paquier wrote:
> > Thanks!
>
> Also, please see also a patch about switching the logirep launcher to
> rely on IsBinaryUpgrade to prevent its startup.  Any thoughts about
> that?
>

Preventing these
+ * processes from starting while upgrading avoids any activity on the new
+ * cluster before the physical files are put in place, which could cause
+ * corruption on the new cluster upgrading to.

I don't think this comment is correct because there won't be any apply
activity on the new cluster as after restoration subscriptions should
be disabled. On the old cluster, I think one problem is that the
origins may move forward after we copy them which can cause data
inconsistency issues. The other is that we may not prefer to generate
additional data and WAL during the upgrade. Also, I am not completely
sure about using the word 'corruption' in this context.

--
With Regards,
Amit Kapila.