I wondering if enabling offline support in the clients for the Firebase Realtime Database saves you any bandwidth? I wonder if the Firebase client when starting loads the database from storage and then continue on and only syncs the stuff that has been added later? Or does it sync everything and if that doesn't work fallbacks to the offline data that he has stored before.
I talked to a Googler today at Google Next Amsterdam and he confirmed the theory that I have. If you have offline support enabled in your app and you are going from offline to online state, Firebase will sync your database in the smartest way possible. So that means that if it's possible it will only send over the changed values. So, enabling offline support does save you bandwidth.