REASSIGN OWNED instructs the system to change the ownership of database objects owned by any of the old_roles to new_role.
The name of a role. The ownership of all the objects within the current database, and of all shared objects (databases, tablespaces), owned by this role will be reassigned to new_role.
The name of the role that will be made the new owner of the affected objects.
REASSIGN OWNED is often used to prepare for the removal of one or more roles. Because REASSIGN OWNED does not affect objects within other databases, it is usually necessary to execute this command in each database that contains objects owned by a role that is to be removed.
REASSIGN OWNED requires privileges on both the source role(s) and the target role.
The DROP OWNED command is an alternative that simply drops all the database objects owned by one or more roles.
The REASSIGN OWNED command does not affect any privileges granted to the old_roles on objects that are not owned by them. Likewise, it does not affect default privileges created with ALTER DEFAULT PRIVILEGES. Use DROP OWNED to revoke such privileges.
See Section 20.4 for more discussion.