My app requires an online DB sync'ed with a local DB. Will Firestore be prohibitively expensive, by either $ or battery, in the following scenario?
The app is free, and intended to store a time series over a period of months to years. These writes will be frequent and low-data (think temperature/acceleration readings, at a rate of 2 mins or less). I have previously implemented a SQLite <-> Datastore sync, but am considering moving to Firestore to take advantage of it's automatic syncing. However: I don't want the user to be pinging the server ever 3 minutes (battery power) and I'm worried that Firestore may prove prohibitively expensive if each individual write is counted as a write vs being able to batch each 30 mins or so.
The app also needs immediate access to the data (for display), and I'd rather fetch all data from the same place. In other words, if I do use the batch commands in Firestore, will that data be available immediately or will it wait until I close the batch?