Swift & Firebase - Cloud firestore scalable?

Question

I'm really new on Cloud Firestore, so it's a bit strange for me to structure the database.

I would like to save my workouts. If I were on RealtimeDatabase I would do something like that:

 WorkoutResults | +--AutoID | | | +--date | +--userID | +--result 

AND

 UserWorkoutResult | +--UserID | | | +--WodResultGeneratedID | 

In that way, I can only fetch one node to a specific user. But if I understand well on Cloud Firestore, it's not possible to query on subcollections.

So my question is, do you think this structure is good enough to scale?

 WorkoutResults | +--AutoID | | | +--date | +--userID | +--result 

By doing something like:

.whereField("userID", isEqualTo: "userIDString").whereField("date", isEqualTo: theDateIWant) ?

Answer 1

Your query looks fine to me. And as Firestore promises, its performance is only related to the number of matching WorkoutResults , not to the size of that collection.

But you could get the exact same result by querying collection("Users").doc("userIDString").collection("WorkoutResults").whereField("date", isEqualTo: theDateIWant) in your first data structure. The only thing that isn't possible there is to query across the WorkoutResults for multiple users, since querying across multiple collections isn't possible.