Garbage collection when using Zend_Session_Handler_DbTable

Question

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.

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.

Answer 1

The Zend_Session_SaveHandler_DbTable class has a garbage collection method called gc which is given to PHP via session_set_save_handler when you call Zend_Session::setSaveHandler().

The gc function should get called periodically based on the php.ini values session.gc_probability and session.gc_divisor. Make sure those values are set to something that would result in garbage collection running at some point.

Also make sure you specify the modifiedColumn and lifetimeColumn options when creating the DbTable save handler because the default gc function uses those columns to determine which rows in the session table are old and should be deleted.