You can add your own library to use native session in codeigniter.
A CodeIgniter library is simply a class that is loaded by the framework and made available for you to use in your Controller classes. We are going to create a new library that starts a native PHP session and allows us to store and retrieve things from it.
Go to application/libraries
Create a file name Native_session.php
Using your new library in a controller.
load->library( 'Native_session' );
//Read the data from session
$username = $this->Native_session->get( 'your data' );
//Update shopping cart session data
$this->Native_session->set( 'cart', $cart );
You can now use your new Native session library in place of the CI-supplied session library.
Hope this article how to use native PHP session in codeigniter will help you.