Realtime Database vs Firestore: Key Differences and When to Use Each

Firebase offers two main databases: Realtime Database stores data as one big JSON tree and syncs in real-time, while Firestore stores data in documents and collections with more powerful queries and better scalability. Choose Realtime Database for simple, low-latency apps and Firestore for complex, scalable apps with richer querying.

Quick Comparison

Here is a quick side-by-side look at the main differences between Realtime Database and Firestore.

Feature	Realtime Database	Firestore
Data Model	Single large JSON tree	Documents and collections
Querying	Basic queries, limited filtering	Advanced queries with compound filters
Scalability	Good for small to medium apps	Designed for large, complex apps
Offline Support	Basic offline syncing	Robust offline support with automatic sync
Pricing	Charged by bandwidth and storage	Charged by document reads, writes, and storage
Real-time Updates	Instant sync on data changes	Real-time with more control and scalability

Key Differences

The Realtime Database stores all data as one big JSON tree. This makes it simple but can get complicated as your data grows because you have to manage nested data carefully. It offers real-time syncing but limited querying options, mostly simple filters and sorting.

Firestore uses a more structured approach with documents grouped into collections. This lets you organize data better and run complex queries with multiple filters and sorting. Firestore also scales better for large apps and supports offline use more robustly, syncing changes automatically when the device reconnects.

Pricing models differ: Realtime Database charges mainly for bandwidth and storage, while Firestore charges based on the number of document reads, writes, and storage, which can affect cost depending on your app's usage pattern.

Code Comparison

Here is how you write and read data in Realtime Database using JavaScript.

javascript

import { initializeApp } from 'firebase/app';
import { getDatabase, ref, set, onValue } from 'firebase/database';

const firebaseConfig = {
  // your config
};

const app = initializeApp(firebaseConfig);
const db = getDatabase(app);

// Write data
set(ref(db, 'users/user1'), {
  name: 'Alice',
  age: 25
});

// Read data
const userRef = ref(db, 'users/user1');
onValue(userRef, (snapshot) => {
  const data = snapshot.val();
  console.log('User data:', data);
});

Output

User data: { name: 'Alice', age: 25 }

Firestore Equivalent

Here is how you write and read the same data in Firestore using JavaScript.

javascript

import { initializeApp } from 'firebase/app';
import { getFirestore, doc, setDoc, onSnapshot } from 'firebase/firestore';

const firebaseConfig = {
  // your config
};

const app = initializeApp(firebaseConfig);
const db = getFirestore(app);

// Write data
await setDoc(doc(db, 'users', 'user1'), {
  name: 'Alice',
  age: 25
});

// Read data
const userDoc = doc(db, 'users', 'user1');
onSnapshot(userDoc, (docSnap) => {
  if (docSnap.exists()) {
    console.log('User data:', docSnap.data());
  }
});

Output

User data: { name: 'Alice', age: 25 }

When to Use Which

Choose Realtime Database when you need simple, low-latency syncing for small to medium apps with straightforward data and limited querying needs. It is great for quick real-time features like chat or live feeds.

Choose Firestore when your app requires complex queries, better data structuring, offline support, and scalability for large user bases. Firestore is ideal for apps with evolving data models and advanced filtering needs.

Key Takeaways

Realtime Database stores data as one JSON tree and is best for simple, real-time syncing.

Firestore uses documents and collections, supporting complex queries and better scaling.

Firestore offers stronger offline support and automatic syncing when back online.

Choose Realtime Database for simple apps with basic queries and Firestore for complex, scalable apps.

Pricing differs: Firestore charges per document operation, Realtime Database charges bandwidth and storage.