I'm currently trying to find a backend solution for my mobile app. I ran into issues in the past with the limited querying power of Cloud Firestore - for instance, you can't return all documents NOT in a sub-collection (inequality-queries).
Ex: Return all users who I have NOT sent a message (not possible in Firestore)
To the best of my knowledge, the only way to accomplish this is to filter locally.
My question is, am I correct that Google's Cloud Functions allows me to write Node.js queries that can perform inequality queries on data stored in Firestore and deploy on Google's cloud environment?