Which data provider are you using in MySQL? I know that InnoDB does not provide optimistic locking? Cache? Nothing like throwing in yet another term. What cache are you thinking about? Are you perhaps thinking of the caching that Hibernate does, since Hibernate is used to implement JPA? The datasource does not do any caching (except for perhaps prepared statements, but that is really being done by the database anyway). JBoss AS does maintain a connection pool of data sources, but that does not involve caching any data. View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4246285#... Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&a...