RE: [PoC] pg_upgrade: allow to upgrade publisher node

Dear Sawada-san,

Thank you for reviewing! New patch set can be available in [1].

> 
> 0001:
> 
> Do we need regression tests to make sure that the slot's
> confirmed_flush_lsn matches the LSN of the latest shutdown_checkpoint
> record?

Added. I wondered the location of the test, but put on
test_decoding/t/002_always_persist.pl.

> 0002:
> 
> +   <step>
> +    <title>Prepare for publisher upgrades</title>
> +
> 
> Should this step be done before "8. Stop both servers" as it might
> require to disable subscriptions and to drop 'lost' replication slots?

Right, moved.

> Why is there no explanation about the slots' confirmed_flush_lsn check
> as prerequisites?

Added.

[1]:
https://www.postgresql.org/message-id/TYCPR01MB5870B5C0FE0C61CD04CBD719F51EA%40TYCPR01MB5870.jpnprd01.prod.outlook.com

Best Regards,
Hayato Kuroda
FUJITSU LIMITED