Re: #XX000: ERROR: tuple concurrently updated

On Thu, Feb 20, 2025 at 4:27 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> Dominique Devienne <ddevienne(at)gmail(dot)com> writes:
> > Error: DDL Error: GRANT USAGE ON SCHEMA "SCH1", "SCH2" TO "SCH2:RO",
> > "SCH2:RW", "SCH2:SU": #XX000: ERROR: tuple concurrently updated
>
> Since both restores tried to grant some permissions on SCH1, they
> both had to update SCH1's pg_namespace row (specifically nspacl).
> We have no support for concurrent updates in the catalog-manipulation
> code, so if the second run arrives at that step before the first
> one has committed its pg_namespace change, you get this error.
>

Hi Tom, and al.

I have a related question, on role-to-role grants this time.

Above, it was contention on pg_namespace.nspacl in two transactions.

But during those "restore" transactions, I must also make role-to-role
grants,
which AFAIK involve adding rows to pg_auth_members. So they are not subject
to the same "no support for concurrent updates in the catalog-manipulation"
you mentioned, as schema-to-role grants are, right? Because that's an
insert,
not an update? Just want to make sure, as I'm thinking how to change our
code.

Thanks, --DD