Re: Two issues with version checks in CREATE SUBSCRIPTION

On Mon, Dec 22, 2025 at 10:57 PM Fujii Masao <masao.fujii@gmail.com> wrote:
>
> While looking at subscription-related code, I noticed two issues related to
> version checks.
>
>         if (walrcv_server_version(wrconn) < 19000)
>             ereport(ERROR,
>                 errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
>                 errmsg("cannot enable retain_dead_tuples if the
> publisher is running a version earlier than PostgreSQL 19"));
>
> First, in subscriptioncmds.c this check rejects enabling retain_dead_tuples
> when the publisher is running an older version. However, the comparison uses
> 19000 as v19 value. Since server versions are encoded as 190000 for v19,
> this appears to be a typo and allows the option to be enabled unexpectedly
> on pre-v19 publishers. The attached 0001 patch fixes this by correcting
> the version constant.
>
> Second, CREATE SUBSCRIPTION with copy_data=true and origin='none' currently
> fails when the publisher is running a version earlier than v19, although
> this combination should be supported. The failure occurs because the command
> issues a query calling pg_get_publication_sequences on the publisher,
> which does not exist before v19. The attached 0002 patch fixes this
> by skipping that query when the publisher runs an older version.
>

The changes look good to me though I haven't tested the patches. So,
please feel free to push after the relevant test. Thanks for catching
and fixing these issues.

--
With Regards,
Amit Kapila.