function get_results_key() {
    global $user;

    if (!isset($this->_results_key)) {
      $key_data = array(
        'build_info' => $this->view->build_info,
        'roles' => array_keys($user->roles),
        'super-user' => $user->uid == 1, // special caching for super user.
        'language' => $GLOBALS['language'],
      );
      foreach (array('exposed_info', 'page', 'sort', 'order') as $key) {
        if (isset($_GET[$key])) {
          $key_data[$key] = $_GET[$key];
        }
      }

      $this->_results_key = $this->view->name . ':' . $this->display->id . ':results:' . md5(serialize($key_data));
    }

    return $this->_results_key;
  }