The problem I'm dealing with is performance issues when needing to perform multiple Firestore queries in order to reach a result similar to to joins in SQL.
In my Flutter app, which uses Firebase and Firestore, I use Cloud Functions for serving my REST API. My API is the only thing that actually interacts with the Firestore database, not the Flutter app itself. I was always taught to design apps like this (not allowing the client to interact directly with the database) and so continued with that approach.
A potential solution I've seen are the official Firestore plugins for Flutter and have seen people designing their clients to interact directly with Firebase, however I haven't found any official documentation explicitly saying this design is preferred or even ok, and since it goes against when have been taught I haven't tried it yet. Can anyone confirm this or point me to documentation confirming this?
Edit Perhaps it's worth noting that the reasons I've been told not to have the client connect directly to the database are 1. Security and 2. It would require business logic for managing data to be in the client and that should be handled server-side.