title: Garbage collection when using Zend_Session_Handler_DbTable
body: <p>I am trying to use Zend_Session_Handler_DbTable to save my session data to the db but as far as i can see, the expired sessions are never deleted from the database. </p>
  
  <p>I can see a cron job running (ubuntu) which deletes the file based sessions but I couldn't find how gc works on sessions which are saving in db.</p>