Firebase

Firebase (Firestore & Realtime Database)

Firebase provides two NoSQL databases:

1. Cloud Firestore: The newer, recommended scalable database.
2. Realtime Database: The original low-latency JSON tree sync.

When to Use

• Mobile Apps: Best-in-class integration with Android/iOS/Flutter.
• Realtime Sync: Chat apps, live dashboards.
• Offline Support: Outstanding offline SDK capabilities.

Quick Start (Firestore)

import { getFirestore, collection, addDoc } from "firebase/firestore";

const db = getFirestore(app);

// Add document
await addDoc(collection(db, "users"), {
  first: "Ada",
  last: "Lovelace",
  born: 1815,
});

Core Concepts

Security Rules

Since you access Firebase from the client, you write JSON-like rules to secure it.

service cloud.firestore {
  match /databases/{database}/documents {
    match /users/{userId} {
      allow read, write: if request.auth.uid == userId;
    }
  }
}

Realtime Updates

Listeners (onSnapshot) keep UI in sync automatically.

Best Practices (2025)

Do:

• Use Firestore Preferentially: It queries and scales better than Realtime DB.
• Use Cloud Functions: For backend logic (sending emails, sanitizing text) triggered by DB events.
• Denormalize: Duplicate data to avoid excessive reads (No joins in Firestore).

Don't:

• Don't use sequential keys: Use auto-generated IDs.
• Don't ignore index limits: Firestore requires composite indexes for sorting/filtering on multiple fields.

References

• Firebase Documentation