何时使用Firebase实时数据库？如何非主数据源场景下结合Rails、Postgres使用？

Absolutely, your proposed setup is totally valid—and it’s actually a common pattern for teams that want to leverage Firebase’s strengths (like easy auth, real-time sync, and frontend integration) while keeping complex relational data in Postgres. Let’s break this down:

Why Your Current Plan Makes Sense #

Firebase’s Realtime Database/Firestore shines for real-time frontend updates (like chat, live dashboards) and simplifying client-side auth, but it’s not ideal for complex joins, ACID-compliant transactions, or heavy relational queries. By using Rails + Postgres as your system of record, and syncing a denormalized version of that data to Firebase for frontend consumption, you get the best of both worlds:

• Postgres handles your core business logic, complex queries, and data integrity.
• Firebase takes care of pushing real-time updates to the frontend without you having to build and maintain something like ActionCable at scale.

Key Considerations for This Setup #

• Async Sync: Don’t sync data to Firebase during the main request cycle—use Rails ActiveJob (or Sidekiq) to handle this asynchronously. This keeps your Rails responses fast and avoids blocking users if Firebase is temporarily unavailable.
• Data Consistency: Plan for sync failures. Add retry logic to your jobs, and consider a way to reconcile discrepancies (e.g., periodic batch syncs for critical data).
• Firebase as Read-Only: If your frontend only reads from Firebase (all writes go through Rails), you avoid conflicts entirely. This is the simplest way to maintain data integrity.

Alternative Ways to Use Firebase Without Its Database as a Source #

If you want to lean into Firebase’s other services without relying on its database, here are some popular patterns:

1. Firebase Auth Only #

Use Firebase’s Auth SDK to handle user authentication (email/password, social logins, password resets) entirely on the frontend. Then, pass Firebase’s idToken to your Rails backend, where you validate it using the Firebase Admin SDK. Once validated, you can create or link a user record in Postgres, and handle all other data operations there. No need to touch Firebase’s database at all—this is great if you just want to offload auth complexity.

2. Firebase Cloud Messaging (FCM) for Notifications #

Keep all your data in Postgres, but use FCM to send push notifications to users. For example, when an order status updates in Rails, trigger a job that calls the FCM API to send a notification to the user’s device. This lets you leverage Firebase’s reliable notification infrastructure without tying into its database.

3. Firebase Storage for File Hosting #

Store user-uploaded files (images, documents) in Firebase Storage instead of a service like S3. Your Rails backend can use the Firebase Admin SDK to upload files, generate signed download URLs, or delete files as needed—all while keeping file metadata (like file names, upload dates) in Postgres.

4. Firebase Hosting for Frontend Deployment #

Host your static frontend (React, Vue, etc.) on Firebase Hosting, and have it talk to your Rails API backend. This gives you Firebase’s fast CDN hosting and easy deployment workflow, with zero dependency on its database services.

5. Firebase Functions for Lightweight Async Tasks #

Offload small, event-driven tasks to Firebase Functions instead of running them in Rails. For example, if a user uploads a profile picture to Firebase Storage, trigger a Function to resize it, then send the resized image URL back to Rails to update the user’s record in Postgres. This keeps your Rails backend focused on core business logic.

At the end of the day, Firebase is a toolkit—you don’t have to use all its services. Mixing and matching with Rails/Postgres is a smart way to build robust, scalable apps that play to each tool’s strengths.

内容的提问来源于stack exchange，提问作者Strawberry