private function runShardCollectionCommand($documentName)
{
$class = $this->dm->getClassMetadata($documentName);
$dbName = $this->dm->getDocumentDatabase($documentName)->getName();
$shardKey = $class->getShardKey();
$adminDb = $this->dm->getConnection()->selectDatabase('admin');
$result = $adminDb->command(array('shardCollection' => $dbName . '.' . $class->getCollection(), 'key' => $shardKey['keys']));
return $result;
}