Re: Re-read subscription state after lock in AlterSubscription

Hi Kuroda-san,

On Fri, Jul 03, 2026 at 03:13:08AM +0000, Hayato Kuroda (Fujitsu) wrote:
> Dear Bertrand,
>
> > Yeah, but I think they would produce "tuple concurrently updated" error (due to
> > CatalogTupleUpdate) so that invalid information could not be used.
>
> I confirmed with PG14 that tuple concurrently updated ERROR can be raised when
> ALTER SUBSCRIPTION DISABLE happens concurrently:
>
> ```
> postgres=# ALTER SUBSCRIPTION sub DISABLE ;
> ERROR: tuple concurrently updated
> ```

Yeah, reproducible by using a breakpoint just before acquiring the lock for example.

> It might be harmless but I think the correct ERROR should be reported: the patch
> should be backpatched. Thought?

I'm not sure about the back patch part as it would only improve error messages
in a rare race condition (and there is no risk of invalid data being used).

Since a5918fddf10, that's a different story because a table creation is now
involved.

Regards,

--
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com