How to Create Indexes in MongoDB using Node.js?

MongoDB, a popular NoSQL database, provides powerful indexing capabilities to improve query performance. Indexes in MongoDB help in quickly locating documents and speeding up read operations. In this tutorial, we'll explore how to create indexes in MongoDB using Node.js.

What is an Index in MongoDB?

In MongoDB, an index is a data structure that improves the speed of data retrieval operations on a collection. It works similarly to indexes in traditional relational databases but is adapted to the document-oriented nature of MongoDB. Indexes allow MongoDB to quickly locate documents in a collection without performing a full collection scan.

Steps to Setup a NodeJS App and Installing Module

Step 1: Create a NodeJS app using the following command

mkdir mongodb-indexes-tutorial
cd mongodb-indexes-tutorial
npm init -y

Step 2: Install the required dependencies using the following command

npm install mongodb

Step 3: Create an app.js file inside the project.

Folder Structure:

The updated dependencies in package.json file will look like:

 "dependencies": {
    "mongodb": "6.6.1",
  },

Connecting to MongoDB

Now, let's create a JavaScript file (e.g., app.js) and establish a connection to MongoDB:

const { MongoClient } = require('mongodb');

const uri = 'mongodb://localhost:27017'; // MongoDB connection URI
const client = new MongoClient(uri);

async function connectToMongoDB() {
    try {
        await client.connect();
        console.log('Connected to MongoDB');
    } catch (error) {
        console.error('Error connecting to MongoDB:', error);
    }
}

connectToMongoDB();

Creating Indexes

MongoDB allows creating indexes on single or multiple fields. Indexes can be created using the createIndex() method provided by the MongoDB Node.js driver. Let's see how to create indexes:

,async function createIndexes() {
    const db = client.db('myDatabase'); // Replace 'myDatabase' with your database name
    const collection = db.collection('myCollection'); // Replace 'myCollection' with your collection name

    try {
        // Create index on a single field
        await collection.createIndex({ fieldName: 1 }); // Replace 'fieldName' with your field name

        // Create compound index on multiple fields
        await collection.createIndex({ field1: 1, field2: -1 }); // Replace 'field1', 'field2' with your field names
    } catch (error) {
        console.error('Error creating indexes:', error);
    }
}

createIndexes();

Index Types

MongoDB supports various types of indexes to optimize different types of queries. Some common index types include:

• Single Field Index: Index created on a single field.
• Compound Index: Index created on multiple fields.
• Text Index: Index created on text fields to support text search.
• Geospatial Index: Index created on geospatial data for location-based queries.
• Hashed Index: Index created using a hash of the indexed field's value.

You can specify the type of index while creating it. For example:

// Create a hashed index
await collection.createIndex({ fieldName: 'hashed' });

Example: Below is an example to create indexes in MongoDB using Node.js:

//app.js

const MongoClient = require('mongodb').MongoClient;

const uri = 'mongodb://localhost:27017';
const dbName = 'your_database_name';

// Create a new MongoClient
const client = new MongoClient(uri, 
    { useNewUrlParser: true, useUnifiedTopology: true });

// Connect to the MongoClient
client.connect(err => {
    if (err) {
        console.error('Error connecting to MongoDB:', err);
        return;
    }

    console.log('Connected to MongoDB successfully');

    const db = client.db(dbName);

    // Create index
    db.collection('your_collection_name')
        .createIndex({ your_field_name: 1 }, (err, result) => {
        if (err) {
            console.error('Error creating index:', err);
            return;
        }

        console.log('Index created successfully:', result);
    });

    // Close the connection
    client.close();
});

Output: