Please allow update_batch with multiple keys

Example:
I have a MySQL table order_details (order_id, product_id, price).
Keys are: order_id and product_id.

Codeigniter should allow update batch with multiple keys like this:

PHP Code:

$data = array(
array(
'order_id' => 1,
'product_id' => 1,
'price' => 99
),
array(
'order_id' => 1,
'product_id' => 2,
'price' => 80
)
);
$this->db->update_batch('order_details', $data, array('order_id', 'product_id') ); 


Please add this feature.