Hi @Kirow, there's definitely value in your modeling approach, but Realm's current inheritance implementation doesn't allow for the polymorphism you're looking for.

Your first goal would be fairly easy to support (avoiding creating unused tables in the db). However, empty tables in Realm are very small so even though this is annoying, it shouldn't have any significant performance or usability impact. If you're keen on filtering which tables are created in Realm, you could patch RLMSchema's +initialize method.

The second goal highlights a more general sore point in Realm's architecture, which is that containers for a class (RLMResults or RLMArray) can't contain instances of its subclass. So for this reason, we can't include subclasses in [RLMObject allObjects] for now.

So for the time being, you'll have to adapt your model to fit with Realm's inheritance approach. Meanwhile, we'll keep an eye on possible modeling improvements for Realm and we'll make sure to update this thread when we have anything to share.

I am having a similar issue to @Kirow's, I have an RLMArray defined to store an abstract class, and storing there subclasses of the abstract class, but of course is giving me back instances of the abstract class.

It will be really awesome if Realm supports this in the future.

realm/realm-java#761 is related issue