[Firebase founder] To offer better querying, improve the data model, and increase scalability we had to build an entirely new database. The original technical choices we made as a startup weren't able to support the featureset Cloud Firestore has. Even if we tried to improve upon the existing Realtime Database product, we would have had to make breaking changes that would have required you to rewrite your code (and likely shipped a worse product).
Regarding deprecation: you can be comfortable continuing to build on the Realtime Database. We don't intend to deprecate either database, since both are useful in different situations, depending on what you're building. We recommend using the Realtime Database for a number of usecases[1]
We're not posting a "Realtime Database will be supported for X years" statement because many may interpret this as "the Realtime Database is deprecating in X years", which isn't the case.
Thanks for the clarification. I certainly feel better with the confirmation. I hope it will give some certainty to thousands of developers out there who decided to make Firebase Realtime Database a critical component of their product architecture.
Regarding deprecation: you can be comfortable continuing to build on the Realtime Database. We don't intend to deprecate either database, since both are useful in different situations, depending on what you're building. We recommend using the Realtime Database for a number of usecases[1]
We're not posting a "Realtime Database will be supported for X years" statement because many may interpret this as "the Realtime Database is deprecating in X years", which isn't the case.
[1] https://firebase.googleblog.com/2017/10/cloud-firestore-for-...