PostgreSQL warnings if "ORDER BY" clause contains a field not mentioned in SELECT

The following line causes warnings if Drupal use PostgreSQL:
$result = db_query(db_rewrite_sql("SELECT n.nid, n.type, n.title FROM {node} n LEFT JOIN {node_revisions} r ON n.nid = r.nid WHERE LOWER(r.title) = LOWER('%s') ORDER BY n.vid DESC"), $page_name);

For correct work this query on PostgreSQL the SELECT part should contain all fields mentioned in ORDER BY.