Resolved ( How to set a session in codeigniter 3 database? )

First of all CI3 session table and CI2 session table( Saving Session Data to a Database)structure is different

New session table structure

 CREATE TABLE IF NOT EXISTS `ci_sessions` (      `id` varchar(40) NOT NULL,      `ip_address` varchar(45) NOT NULL,      `timestamp` int(10) unsigned DEFAULT 0 NOT NULL,      `data` blob NOT NULL,      PRIMARY KEY (id),      KEY `ci_sessions_timestamp` (`timestamp`)  );

Second They support old configuration variables with new configuration but it is better to use new configuration

$config['sess_driver'] = 'database';  $config['sess_cookie_name'] = 'ci_sessions';  $config['sess_expiration'] = 7200;  $config['sess_save_path'] = 'ci_sessions';//its your table name name  $config['sess_match_ip'] = FALSE;  $config['sess_time_to_update'] = 300;

See more details at their docs

Few new feature(function) available for session library.

Remember Don't forget it to load via autoload.php or loading $this->load->library('session');before use it.