Re: BUG #18988: DROP SUBSCRIPTION locks not-yet-accessed database

On Wed, Aug 13, 2025 at 3:00 PM Dilip Kumar <dilipbalaut@gmail.com> wrote:
>
> I have prepared back branch patches.
>

@@ -1802,11 +1802,7 @@ DropSubscription(DropSubscriptionStmt *stmt,
bool isTopLevel)
...
- /*
- * Lock pg_subscription with AccessExclusiveLock to ensure that the
- * launcher doesn't restart new worker during dropping the subscription
- */
- rel = table_open(SubscriptionRelationId, AccessExclusiveLock);
+ rel = table_open(SubscriptionRelationId, AccessShareLock);

We need to acquire RowExclusiveLock here as we are deleting the
subscription row during this operation. See docs [1] and
AlterSubscription() code for reference. Attached is a top-up patch to
fix this for HEAD. Additionally, I have edited a few comments. If you
agree with these changes then please prepare backbranch patches
accordingly.

[1] - https://www.postgresql.org/docs/devel/explicit-locking.html
--
With Regards,
Amit Kapila.