title: POSTGRES - superuser can't access pg_authid table
body: <p>Have RDS postgres instance and checked user access like this:</p>
  
  <pre><code>SELECT 
        r.rolname, 
        ARRAY(SELECT b.rolname
              FROM pg_catalog.pg_auth_members m
              JOIN pg_catalog.pg_roles b ON (m.roleid = b.oid)
              WHERE m.member = r.oid) as memberof
  FROM pg_catalog.pg_roles r
  WHERE r.rolname NOT IN ('pg_signal_backend','rds_iam',
                          'rds_replication','rds_superuser',
                          'rdsadmin','rdsrepladmin')
  ORDER BY 1; 
  </code></pre>
  
  <p>and user X is in <strong>{rds_superuser}</strong> yet when I run</p>
  
  <pre><code>SELECT * FROM pg_authid;
  </code></pre>
  
  <p>getting</p>
  
  <pre><code>ERROR: permission denied for relation pg_authid
  </code></pre>
  
  <p>Tried <code>GRANT ALL PRIVILEGES ON TABLE pg_authid TO vanare;</code></p>
  
  <p>Any ideas what I am missing here? Thank you.</p>