What is the best pattern for storing multiple versions of the same entity? Two tables? One for the entity X and another to store all the versioned data?

I've played around with the <version> mapping, and I don't think this does what I want it to do. I think it's used for something entirely differently.

I guess what I want to do is something like a version control system... where I keep track of every snapshot that ever existed for the entity, and thus have the ability to compare between the various versions.

My best guess is a 2 table solution, or a primary key with the entity_id and the version_id, and then I increment the version every time and also insert rather than update.

Is there something a bit more framework-y for this though? Transparency would be great.

If you have one table, a second archive table might make sense.

If you're looking for a framework-y way hook, there are several ways: JPA-style, Events or Interceptors.

http://docs.jboss.org/hibernate/stable/entitymanager/reference/en/html/listeners.html
http://docs.jboss.org/hibernate/core/3.3/reference/en/html/events.html

HIA describes this in 12.3.2 as well.

I guess a second table looks to be the best option. I can always archive the last version, that way I never have to muck with the current version. It will work like every other table.