Adding index without model migration

I have an app that's been in the App Store for a while, using Core Data to save information. In my Core Data model, I have an entity that I haven't ever used till now, and I am planning to add an index on a property in this entiity, and with this update, start to also add data to this entity. This is the only change I plan to make right now, and I believe this will not trigger any automatic lightweight migration (which I want to avoid).


So my question is: without the lightweight migration, will the new index even be created? I'm confused because this could result in two scenarios: either an index is created but existing data isn't indexed (which is just fine by me), or an index isn't created at all till a lightweight migration happens (which is undesirable). Would be great to know what the expected behavior is in this case.