Spend a few days with Grails and you will see the power of Hibernate. The tools do an excellent job of generating an impressive database design from an object model. For 'application' databases, this is all you need. When connecting to an Enterprise database, you probably will need to write your own mapping, but you then have a great deal of power. Heck, you can even use PostgreSQL and see how aggregates & window functions should be implemented in a relational database.