Can someone confirm something for me? It seems that pg_dump with the -o option preserves OIDS for user objects, but does not preserve the OIDs for objects in system tables. Is that correct?
[...]
The app has a table that associates a user (role) with a "department" by inserting a row into a table with the values 'usesysid' from pg_user and a department
"pg_dump" doesn't dump roles. They are global and handled via "pg_dumpall".