Firebase offline capabilities as cache

Question

I am wondering whether it is a sound strategy to use the firebase offline capabilities as a "free" cache.

Let's assume that I am in activity A, I fetch some data from firebase, and then I move to activity B, which needs the same data. If the app is configured with setPersistenceEnabled(true) and, if necessary, also with keepSynced(true), can I just re-query the same data in activity B, rather that passing it around?

I understand that there is a difference between the two approaches regarding reading-from-memory and reading-from-disk (firebase offline cache). But do I really get rid of all the network overhead by using firebase offline?

Relevant links:
Firebase Offline Capabilities and addListenerForSingleValueEvent https://groups.google.com/forum/#!msg/firebase-talk/ptTtEyBDKls/XbNKD_K8CQAJ

Answer 1

Yes, you can easily re-query your Firebase Database in each activity instead of passing data around. If you enable disk persistence, this will be a local read operation. But since you attach a listener (or keep it attached through keepSynced()), it will cause network traffic.

But don't use Firebase as an offline-only database. It is really designed as an online database that can work for short to intermediate periods of being disconnected. While offline it will keep queue of write operations. As this queue grows, local operations and app startup will slow down. Nothing major, but over time these may add up.