What is the difference between firestore database and realtime database in firebase ?

Overview

Firebase offers two cloud database options: Cloud Firestore and the Realtime Database. Both are NoSQL databases that sync data in real-time, but they differ significantly in structure, performance, and capabilities.

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Quick Comparison

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Cloud Firestore

Firestore stores data as documents inside collections. Documents can contain subcollections, allowing hierarchical data.

Data Structure

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users (collection)
  └── user_001 (document)
        ├── name: "Alice"
        ├── email: "alice@example.com"
        └── orders (subcollection)
              └── order_01
                    ├── item: "Book"
                    └── price: 300

Flutter Usage

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import 'package:cloud_firestore/cloud_firestore.dart';

final db = FirebaseFirestore.instance;

// Add a document
await db.collection('users').doc('user_001').set({
  'name': 'Alice',
  'email': 'alice@example.com',
  'createdAt': FieldValue.serverTimestamp(),
});

// Rich query with filters and ordering
final snapshot = await db
    .collection('users')
    .where('age', isGreaterThan: 18)
    .orderBy('name')
    .limit(10)
    .get();

// Real-time stream
db.collection('users').snapshots().listen((snapshot) {
  for (var doc in snapshot.docs) {
    print(doc.data());
  }
});

Firestore Pros

• ✅ Rich query capabilities (filters, ordering, pagination)
• ✅ Scales to very large data sets
• ✅ Multi-region availability
• ✅ Better security rules (field-level)
• ✅ Strong offline support

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Realtime Database

Realtime Database stores data as a single, large JSON tree. All data exists in one flat structure.

Data Structure

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{
  "users": {
    "user_001": {
      "name": "Alice",
      "email": "alice@example.com"
    }
  },
  "messages": {
    "msg_001": {
      "text": "Hello!",
      "userId": "user_001"
    }
  }
}

Flutter Usage

dartCopy
import 'package:firebase_database/firebase_database.dart';

final db = FirebaseDatabase.instance;

// Write data
await db.ref('users/user_001').set({
  'name': 'Alice',
  'email': 'alice@example.com',
});

// Read data once
final snapshot = await db.ref('users/user_001').get();
print(snapshot.value);

// Real-time listener
db.ref('messages').onValue.listen((event) {
  print(event.snapshot.value);
});

Realtime Database Pros

• ✅ Lower latency for simple data
• ✅ Simpler structure for basic use cases
• ✅ Better for frequent, small data updates (e.g., live cursor positions)
• ✅ Cheaper for high-volume small reads

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When to Use Which?

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Pricing Difference

Recommendation: For any new Flutter project, use Cloud Firestore. It is more powerful, scalable, and officially recommended by Google. Use Realtime Database only if you have a specific use case like very low-latency live collaboration features.

Learn more: Firebase - Choose a Database