How to store session in DB

I added connectionID as db but still it is taking path for sqlite file.

Below are config

‘session’ => array(

'class' => 'CDbHttpSession',


'autoStart' => true,


'connectionID' => 'db_master',


'sessionTableName' => 'cc_session',


'autoCreateSessionTable' => true 

),

While creating session I am doing :

$session = new CDbHttpSession();

My site has dynamic sub domains functionality as soon as some one registers.