GcpComparisonBeginner · 4 min read

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

Firestore is a newer, more scalable NoSQL database with richer querying and offline support, while Realtime Database is an older, simpler JSON tree database optimized for low-latency syncing. Choose Firestore for complex queries and large apps, and Realtime Database for simple, real-time syncing needs.

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Quick Comparison

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

Feature	Firestore	Realtime Database
Data Model	Documents and collections	JSON tree
Querying	Rich, indexed queries	Limited, shallow queries
Offline Support	Built-in offline support	Basic offline support
Scalability	Highly scalable	Less scalable
Latency	Low latency, but slightly higher than Realtime Database	Very low latency
Pricing	Pay per document read/write	Pay per bandwidth and storage

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Key Differences

Firestore uses a document-based model where data is stored in documents grouped into collections. This structure allows for complex, indexed queries and hierarchical data organization. It supports offline data access and syncs changes when the device reconnects.

Realtime Database stores data as one large JSON tree. It is optimized for simple, real-time syncing of data with very low latency but has limited querying capabilities and can become complex to manage as data grows.

Firestore scales automatically to handle large amounts of data and users, while Realtime Database can face performance issues at scale. Firestore charges based on operations like reads and writes, whereas Realtime Database pricing is based on bandwidth and storage used.

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Code Comparison

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

javascript

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

const firebaseConfig = {
  // your config
};

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

async function writeUserData(userId, name, email) {
  await setDoc(doc(db, 'users', userId), {
    name: name,
    email: email
  });
}

async function readUserData(userId) {
  const docRef = doc(db, 'users', userId);
  const docSnap = await getDoc(docRef);
  if (docSnap.exists()) {
    console.log('User data:', docSnap.data());
  } else {
    console.log('No such document!');
  }
}

writeUserData('user123', 'Alice', 'alice@example.com');
readUserData('user123');

Output

User data: { name: 'Alice', email: 'alice@example.com' }

↔️

Realtime Database Equivalent

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

javascript

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

const firebaseConfig = {
  // your config
};

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

function writeUserData(userId, name, email) {
  set(ref(db, 'users/' + userId), {
    name: name,
    email: email
  });
}

async function readUserData(userId) {
  const userRef = ref(db, 'users/' + userId);
  const snapshot = await get(userRef);
  if (snapshot.exists()) {
    console.log('User data:', snapshot.val());
  } else {
    console.log('No data available');
  }
}

writeUserData('user123', 'Alice', 'alice@example.com');
readUserData('user123');

Output

User data: { name: 'Alice', email: 'alice@example.com' }

🎯

When to Use Which

Choose Firestore when your app needs complex queries, hierarchical data, offline support, and scalability for many users. It is ideal for apps that grow over time and require flexible data access.

Choose Realtime Database when your app needs very low latency syncing of simple data structures and you want a straightforward setup. It works well for small apps or features like live chat where real-time updates are critical.

✅

Key Takeaways

Firestore offers richer queries and better scalability than Realtime Database.

Realtime Database provides very low latency syncing with a simple JSON tree model.

Use Firestore for complex, large-scale apps with offline needs.

Use Realtime Database for simple, real-time syncing with minimal setup.

Pricing models differ: Firestore charges per operation; Realtime Database charges by bandwidth and storage.