Dropping a role has the effect of removing the role from the database
dictionary. This means that no session user can henceforth set that role (see
SET ROLE statement), and any existing sessions
that have that role as the current role (see
CURRENT_ROLE function) will now have a NULL
CURRENT_ROLE. Dropping a role also has the effect of revoking that role from any
user and role it has been granted to. See
REVOKE statement for information on how
revoking a role may impact any dependent objects.