title: Deleting expired sessions from mysql
body: <p>I am using perl and mysql for storing user sessions. If an user click logout, i can able to delete the session. But if the session expires, it fills the database like zombies. So i have to delete the session by parsing into every users session data and retrieve session's last access time and then delete it, if it is not accessed for more than an hour. Its moreover an hack. Is there any clean way of doing that?
  If there is anything in mysql like automatic deletion of sessions when it get expired.</p>