Find schema-qualified table name given unqualified name

Aron Widforss <pgsql-general@antarkt.is> writes:

I'm interested in finding a (any) unique identifier for a table given an unqualified name of the table. Is that feasible in SQL or a C function?

Something like this might help you:

select relnamespace::regnamespace from pg_class
where oid = 'mytablename'::regclass;

This will fail (not just return an empty set) if 'mytablename' isn't
resolvable, so you might need some hackery to cope with that. Also,
if you need it to work pre-9.5, you'll need to write an explicit
join to pg_namespace instead of relying on regnamespace.

regards, tom lane