Dear Takahashi-san,
Thanks for giving feedbacks!
> > I don't know if it requires the kind of code you are thinking but I
> > agree that it is worth considering implementing it as an extension.
>
> I think the other advantage to implement as an extension is that users could
> install the extension to older Postgres.
>
> As mentioned in previous email, the one use case of n-way replication is migration
> from older Postgres to newer Postgres.
>
> If we implement as an extension, users could use n-way replication for migration
> from PG10 to PG16.
>
I think even if LRG is implemented as contrib modules or any extensions,
it will deeply depend on the subscription option "origin" proposed in [1].
So LRG cannot be used for older version, only PG16 or later.
[1]: https://www.postgresql.org/message-id/CALDaNm3Pt1CpEb3y9pE7ff91gZVpNXr91y4ZtWiw6h+GAyG4Gg@mail.gmail.com
Best Regards,
Hayato Kuroda
FUJITSU LIMITED
