Thread: Fwd: Adding more detail to pg_upgrade documentation

Hi Nikhil,

From the pgupgrade docs:

> 9. Prepare for standby server upgrades
> 
> If you are upgrading standby servers using methods outlined in section
> Step 11, verify that the old standby servers are caught up by running
> pg_controldata against the old primary and standby clusters. Verify
> that the “Latest checkpoint location” values match in all clusters.
> (There will be a mismatch if old standby servers were shut down before
> the old primary or if the old standby servers are still running.)
> Also, make sure wal_level is not set to minimal in the postgresql.conf
> file on the new primary cluster.

(source: https://www.postgresql.org/docs/devel/pgupgrade.html)

I'm a new contributor so please forgive me if I'm on the wrong track,
but if you follow this step, won't you also be ensuring that replication
slots do not need to be migrated, since you've just ensured that standby
clusters are in sync with the primary cluster? Please let me know if I'm
missing anything!

Thank You,
Jack DeVries

On Sat, Jun  4, 2022 at 03:08:58PM +0530, Nikhil Shetty wrote:
> Hi Jack,
> 
> I followed the same steps multiple times but each time, slot had to be
> recreated.
> 
> The slots under directory pg_replslot are not created in the new cluster during
> pg_upgrade.
> 
> Thanks and Regards,
> Nikhil
> 
> On Sat, 4 Jun 2022 at 1:48 AM, Jack DeVries <jdevries3133@gmail.com> wrote:
> 
>     Hi Nikhil,
> 
>     >From the pgupgrade docs:
> 
>     > 9. Prepare for standby server upgrades
>     >
>     > If you are upgrading standby servers using methods outlined in section
>     > Step 11, verify that the old standby servers are caught up by running
>     > pg_controldata against the old primary and standby clusters. Verify
>     > that the “Latest checkpoint location” values match in all clusters.
>     > (There will be a mismatch if old standby servers were shut down before
>     > the old primary or if the old standby servers are still running.)
>     > Also, make sure wal_level is not set to minimal in the postgresql.conf
>     > file on the new primary cluster.
> 
>     (source: https://www.postgresql.org/docs/devel/pgupgrade.html)
> 
>     I'm a new contributor so please forgive me if I'm on the wrong track,
>     but if you follow this step, won't you also be ensuring that replication
>     slots do not need to be migrated, since you've just ensured that standby
>     clusters are in sync with the primary cluster? Please let me know if I'm
>     missing anything!

I have written the attached patch to document this.

-- 
  Bruce Momjian  <bruce@momjian.us>        https://momjian.us
  EDB                                      https://enterprisedb.com

  Indecision is a decision.  Inaction is an action.  Mark Batterson

On Sat, Jul  9, 2022 at 10:38:30PM -0400, Bruce Momjian wrote:
> >     (source: https://www.postgresql.org/docs/devel/pgupgrade.html)
> > 
> >     I'm a new contributor so please forgive me if I'm on the wrong track,
> >     but if you follow this step, won't you also be ensuring that replication
> >     slots do not need to be migrated, since you've just ensured that standby
> >     clusters are in sync with the primary cluster? Please let me know if I'm
> >     missing anything!
> 
> I have written the attached patch to document this.

Patch applied to all supported versions.

-- 
  Bruce Momjian  <bruce@momjian.us>        https://momjian.us
  EDB                                      https://enterprisedb.com

  Indecision is a decision.  Inaction is an action.  Mark Batterson