Re: CREATE SUBSCRIPTION ... SERVER vs. pg_dump, etc.

On Wed, 2026-07-29 at 14:30 -0700, Jeff Davis wrote:
> Proposal:
>
>  * Form a conninfo if and only if a connection is immediately
>    required. That is, it's one of the DDL commands above, or a
>    logical worker.
>
>  * Check USAGE on the server when a connection is formed or when
>    ALTER sets the server or when the subscription owner changes
>    (unless superuser changes the owner, in which case it may be part
>    of a multi-command DDL sequence during restore).
>
>  * Check that the server's FDW supports a connection function when
>    DDL sets the subscription's server.
>
>  * Check that a user mapping exists during DDL when the server or
>    owner changes, but demote the message to a WARNING, because it
>    may be part of a multi-command DDL sequence during restore.
>    - CREATE SUBSCRIPTION already issues WARNINGS during restore.
>
>  * Ensure that none of the commands during restore need a connection.
>    - check_pub_rdt should happen at connection time, and only
>      opportunistically at DDL time if already forming a connection
>
>  * Check walrcv_check_conninfo() before connecting, or during
>    CREATE/ALTER SUBSCRIPTION ... CONNECTION.
>    - If a connection is not needed for DDL, and it's a server-based
>      subscription, walrcv_check_conninfo() will be called only by
>      the logical worker when a connection is needed.
>    - That loses some convenience for interactive DDL, but avoids
>      false positive failures during restore.

Here's a consolidated series of commits.

Fujii, note that this includes a revert of your commit 1c9c358904.
Doing too much validation can cause problems for restore.

Amit, this series does not include the check_pub_rdt change to move it
to the worker.

Shlok Kyal, the change to detect when a refresh is happening is in my
patch 0006, the ACL check fix is in my patch 0007.

Hayato Kuroda, Amit already pushed the --no-subscriptions fix
(02decf9a9a). I didn't change the dump/restore order in this series,
because reducing the errors seems right for v19. We can reconsider it
for v20.

Regards,
Jeff Davis