Как сортировать leftjoin?

$pdoFetch->getObject('Ticket', $row['id'], array(
			'leftJoin' => array(
				'LastComment' => array('class' => 'TicketComment', 'on' => '`LastComment`.`thread` = '.$row['thread']),
			),
			'select' => array(
				'LastComment' => '`LastComment`.`raw` as `last_comment`',
			),
			'sortby' => array(
				'LastComment' => '`LastComment`.`id`',
			),
			'sortdir' => array(
				'LastComment' => 'ASC',
			),
			'groupby' => $class.'.id'
		));