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

Dear Amit,

Thank you for reviewing! 

> 
> I also think referring to the conflicting field would be better not
> only for the purpose of avoiding extra code but also to give accurate
> information about invalidated slots for which we want to give an
> error.

Fixed.

> Additionally, I think we should try to avoid writing a new function
> strtoLSN as that adds a maintainability burden. We can probably send
> the value fetched from pg_controldata in the query for comparison with
> confirmed_flush LSN.

Changed like that. LogicalSlotInfo was also updated to have the Boolean.

Best Regards,
Hayato Kuroda
FUJITSU LIMITED