Intermediate LevelMongoDB & Mongoose
How do MongoDB Change Streams enable real-time database event notifications?
❓ Interview Prompt: Explain Change Streams, tailing replica set Oplog, change stream events (insert, update, replace, delete), resume tokens, and real-time triggers.
Change Streams allow Node.js applications to access real-time data changes without polling by opening a tailing cursor over the replica set Oplog:
Event Notifications:
Emits event objects containing modified document IDs, operation types ('insert', 'update', 'delete'), and full document snapshots.
Code Implementation Example
typescript
import { OrderModel } from './models/Order';
function listenToRealtimeOrders() {
const changeStream = OrderModel.watch([
{ $match: { 'fullDocument.status': 'COMPLETED' } }
]);
changeStream.on('change', (change) => {
console.log('New Completed Order Event:', change.documentKey._id);
});
}💡Listening to real-time database change events using Mongoose watch().
🎯 Interview Key Takeaway
Use Change Streams over Oplog tailing to trigger real-time microservice events without expensive database polling.
#Change Streams#watch()#Real-Time#Oplog#Intermediate
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