Re: Proposal: Conflict log history table for Logical Replication

On Wed, May 6, 2026 at 3:06 PM shveta malik <shveta(dot)malik(at)gmail(dot)com> wrote:
>
> As a non super-user which does not have 'pg_create_subscription' privelege:
> postgres=> alter table pg_conflict.pg_conflict_16487 add column i int;
> ERROR: permission denied for schema pg_conflict
> <seems correct, as access is denied at schema level itself>
>
> As a non super-user which has 'pg_create_subscription' privelege, but
> does not own the respective sub:
> postgres=> alter table pg_conflict.pg_conflict_16487 add column i int;
> ERROR: must be owner of table pg_conflict_16487
> <Due to 'pg_create_subscription', it seems schema access is provided,
> so it goes to check table access now and gives above error. Not sure
> about this error, even if the user were the owner, they still wouldn't
> be able to perform this operation>
>
> As a non super-user which has 'pg_create_subscription' privilege and
> also owns the respective sub:
> postgres=> alter table pg_conflict.pg_conflict_16498 add column i int;
> ERROR: permission denied: "pg_conflict_16498" is a system catalog
> <okay>
>
> As a super-user, the error is same irrespective of fact whether it
> actually owns that table or not:
> postgres=# alter table pg_conflict.pg_conflict_16487 add column i int;
> ERROR: permission denied: "pg_conflict_16487" is a system catalog
> <okay>
>
> For second case, not a strong opinion, but can the better error be:
> ERROR: permission denied: "pg_conflict_16487" is a system catalog?
>
> I have not analyzed code myself for this yet.
>

I analyzed this case and think that the current behavior is okay. As
per RangeVarCallbackForAlterRelation(), we first ensure that the
current user is either a table owner or superuser and then check
actual permissions to perform the operations on the table. The same is
true for the DROP case. I don't see the need to change it.

Few cosmetic changes are attached in top-up patches. Dilip can include
these in the next version, if he is okay with them.

--
With Regards,
Amit Kapila.