p_hash` char(32) NOT NULL DEFAULT '',
  `created` int(10) unsigned NOT NULL DEFAULT '0',
  `updated` int(10) unsigned NOT NULL DEFAULT '0',
  `payload` longtext NOT NULL,
  PRIMARY KEY (`session_id`),
  UNIQUE KEY `PREVIOUS` (`previous_id`)
) ENGINE=INNODB DEFAULT CHARSET=utf8;
</pre><br />
									Note that the sessions table has a unique index on both the session_id and the previous_id columns. This is both to speed up the query (which is always by id), and to make sure no duplicate id's are inserted.
		