The view usage_privileges is meant to identify
   USAGE privileges granted on various kinds of
   objects to a currently enabled role or by a currently enabled role.
   In PostgreSQL, this currently only
   applies to domains, and since domains do not have real privileges
   in PostgreSQL, this view shows implicit
   USAGE privileges granted to
   PUBLIC for all domains.  In the future, this
   view may contain more useful information.
  
Table 32-41. usage_privileges Columns
| Name | Data Type | Description | 
|---|
| grantor | sql_identifier | Currently set to the name of the owner of the object | 
| grantee | sql_identifier | Currently always PUBLIC | 
| object_catalog | sql_identifier | Name of the database containing the object (always the current database) | 
| object_schema | sql_identifier | Name of the schema containing the object | 
| object_name | sql_identifier | Name of the object | 
| object_type | character_data | Currently always DOMAIN | 
| privilege_type | character_data | Always USAGE | 
| is_grantable | character_data | Currently always NO |