Index management in Firebase - Mini Project: Build & Apply

Firebase Firestore Index Management

📖 Scenario: You are building a simple app to store and retrieve user profiles in Firebase Firestore. To make queries faster and more efficient, you need to create and manage indexes.

🎯 Goal: Learn how to create a Firestore collection, add documents, configure a composite index, and query the collection using the index.

📋 What You'll Learn

Create a Firestore collection called users with specific user documents

Add a configuration variable for the index fields

Write a Firestore query that uses the composite index

Complete the Firestore index configuration to enable the query

💡 Why This Matters

🌍 Real World

Managing indexes in Firestore helps apps run faster and handle complex queries efficiently, especially as data grows.

💼 Career

Understanding Firestore index management is essential for backend developers and cloud engineers working with Firebase to optimize database performance.

1

Create the users collection with documents

Create a Firestore collection called users and add three documents with these exact fields and values: { name: 'Alice', age: 30, city: 'New York' }, { name: 'Bob', age: 25, city: 'Los Angeles' }, and { name: 'Charlie', age: 35, city: 'Chicago' }.

Firebase

// Add three user documents to the 'users' collection
// Your code here

Need a hint?

Use firestore.collection('users') to get the collection reference, then add documents with doc().set().

2

Add index configuration for age and city

Create a configuration object called indexConfig with fields collectionGroup set to 'users' and fields set to an array containing { fieldPath: 'age', order: 'ASCENDING' } and { fieldPath: 'city', order: 'ASCENDING' }.

Firebase

const users = firestore.collection('users');

users.doc('user1').set({ name: 'Alice', age: 30, city: 'New York' });
users.doc('user2').set({ name: 'Bob', age: 25, city: 'Los Angeles' });
users.doc('user3').set({ name: 'Charlie', age: 35, city: 'Chicago' });

// Create indexConfig object with collectionGroup and fields
// Your code here

Need a hint?

Define indexConfig as an object with collectionGroup and fields array specifying the index fields and order.

3

Write a Firestore query using the composite index

Write a query called queryUsers on the users collection that filters where age is greater than 25 and orders the results by city ascending.

Firebase

const users = firestore.collection('users');

users.doc('user1').set({ name: 'Alice', age: 30, city: 'New York' });
users.doc('user2').set({ name: 'Bob', age: 25, city: 'Los Angeles' });
users.doc('user3').set({ name: 'Charlie', age: 35, city: 'Chicago' });

const indexConfig = {
  collectionGroup: 'users',
  fields: [
    { fieldPath: 'age', order: 'ASCENDING' },
    { fieldPath: 'city', order: 'ASCENDING' }
  ]
};

// Write a query called queryUsers filtering age > 25 and ordering by city ascending
// Your code here

Need a hint?

Use where('age', '>', 25) and orderBy('city', 'asc') chained on the users collection.

4

Complete the Firestore index configuration

Add a final property queryScope with value 'COLLECTION' to the indexConfig object to complete the composite index configuration.

Firebase

const users = firestore.collection('users');

users.doc('user1').set({ name: 'Alice', age: 30, city: 'New York' });
users.doc('user2').set({ name: 'Bob', age: 25, city: 'Los Angeles' });
users.doc('user3').set({ name: 'Charlie', age: 35, city: 'Chicago' });

const indexConfig = {
  collectionGroup: 'users',
  fields: [
    { fieldPath: 'age', order: 'ASCENDING' },
    { fieldPath: 'city', order: 'ASCENDING' }
  ]
};

const queryUsers = users.where('age', '>', 25).orderBy('city', 'asc');

// Add queryScope: 'COLLECTION' to indexConfig
// Your code here

Need a hint?

Add queryScope: 'COLLECTION' inside the indexConfig object.