Yii2 clone作用 [ 2.0 版本 ]

use yii\data\Pagination;
$query = Article::find()->where(['status' => 1]);
$countQuery = clone $query;
$pages = new Pagination(['totalCount' => $countQuery->count()]);
$models = $query->offset($pages->offset)
  ->limit($pages->limit)
  ->all();
return $this->render('index', [
  'models' => $models,
  'pages' => $pages,
]);

分页的时候代码网上都要加$countQuery = clone $query;这句 ，具体作用是什么，我去掉也不影响.有什么特别作用吗？？