I am storing an Entity A during my datastore on appengine. A comes with an id of type Lengthy. Let me keep past all changes designed to A's fields. Do you know the guidelines to doing this kind of version ing on organizations? I'd should you prefer a solution that work well with subclasses of the and it is as automatic as you possibly can.

Thanks!

We're doing such like for our AppEngine applications. The only real efficient approach we take to found was, come with an Entity B which are your versions, and Entity A keeps a listing of secrets.

Then we use ETags within our Relaxation services to recognize which version our client will get a duplicate of.

You can produce a linked listing of organizations, where each entity has two references: someone to its previous version and something to another version. You need to maintain individuals references yourself, obviously. The newest version of the entity would be the one with no mention of the a next version (or perhaps an empty/null reference).

Based on your use situation you could also want to check out methods to only keep variations between two version of the entity (if changes are small , organizations are large).