From an RDB perspective, saving an Auditable results in the creation of a new row in some table in the database, rather than updating a pre-existing row (I think JoeG said this was a pretty common pattern, but I’m not a persistence wonk so I’m not sure).

In theory, since clients interact with high-level repository APIs rather than RDB-centric APIs (like JDBC), if a persistence mechanism came along that provided native versioning support, and still provided adequate concurrency and query capabilities, we could switch to that native mechanism without clients noticing. But I don’t expect this to happen anytime soon. Also, it’s a stretch to claim that “the RDB is an implementation detail” when it’s the only implementation; I’m sure the law of leaky abstractions would rear its ugly head if/when we tried to plug in the second implementation.

I don’t follow what you’re saying about “Content”. To me “Content” means “A dataset whose structure is opaque to the Repository”. I.e. from the server’s perspective it’s just a sequence of bytes (though it might have some structure which the server simply doesn’t understand). We have such a notion in Jazz, and it’s straightforward to use the same Auditable versioning mechanism. Simply wrap a Content object in an Auditable. E.g. define a new Auditable type called “File” which has a single attribute “content” referencing a content object (obviously you’d want more attributes for a file). I don’t know if what I’ve just described has anything to do with what you were talking about but I’d be interested to hear if what I said raised or settled any issues.

True. IBM Rational Jazz does version data in its Repository implementation. But I believe, like most systems that version its data, it is solved at the application layer rather than the persistence layer. Generally not true when the data is called ‘content’.

To most, data is synonymous with SQL. As such, is there a relational database that versions data transparent to the application, yet provide hooks for the application to retrieve versions?

So, perhaps it may be relevant to ask whether all data is so called ‘content’?