activerecord - CodeIgniter Update Batch with Multiple Index -

i'm having problem active record update batch on codeigniter.

on documentation,

$this->db->update_batch('mytable', $data, 'title'); 

where 'title' index update process. possible have 2 or more index active record? tried

$this->db->update_batch('mytable', $data, 'title, title_2'); $this->db->update_batch('mytable', $data, array('title', 'title_2'); 

and it's not working.