MongoDB Change Streams: Real-Time Updates Made Easy

📌 1) Introduction

In today’s real-time world, users expect instant updates — whether it's live chats, dashboards, or collaborative apps.
MongoDB Change Streams allow you to listen to real-time changes in your database without using complex polling or cron jobs.

This feature is available only for replica sets and enables you to react instantly to changes like insert, update, delete operations on documents.

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🧠 2) What are MongoDB Change Streams?

Change Streams are a MongoDB feature that lets applications subscribe to changes in collections. You can listen to:

• Insertions

• Updates

• Deletions

• Replace operations

It is commonly used in:

• Real-time analytics

• Activity logs

• Notifications

• Chat/messaging apps

⚠️ Note: Change Streams require MongoDB to run in replica set mode.

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⚙️ 3) Step-by-Step Procedure

✅ Step 1: Start MongoDB with Replica Set

Start mongod with replication enabled:

mongod --dbpath "C:\data\replica" --replSet rs0

✅ Step 2: Open Mongo Shell and Initiate Replica

Open new terminal and run:

mongosh

rs.initiate()

✅ Step 3: Create Sample Database and Collection

use shopDB

db.orders.insertOne({ item: "Mobile", price: 15000 })

✅ Step 4: Open a Change Stream Cursor

var changeStream = db.orders.watch()

✅ Step 5: Monitor Real-Time Changes

changeStream.next()

✅ Step 6: Insert Another Document from Another Shell

In another mongosh window:

use shopDB
db.orders.insertOne({ item: "Laptop", price: 52000 })

Your first terminal will now immediately detect the change.

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🔮 4) Future Scope

Change Streams are powerful and can be integrated with:

• Kafka, RabbitMQ, or WebSockets for message broadcasting

• Real-time notification systems

• Microservices and event-driven architectures

• Dashboards that update live without refresh

As MongoDB continues to grow, Change Streams are a key feature for real-time applications.

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Sumit Sonwane

University: Sri Balaji University, Pune

School: School of Computer Studies

Course: BCA (Bachelor of Computer Applications)

Interests: NoSQL, MongoDB, and related technologies

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