Change StreamsAdvanced
1Question 1 of 1
javascriptWhat are MongoDB Change Streams and how do they enable real-time reactive architectures?
Explanation & Concept
Change Streams allow applications to access real-time data changes across a collection, database, or entire deployment without polling. They leverage the MongoDB replica set `oplog` and stream notifications with low latency.
Applications can filter change events by operation type (`insert`, `update`, `replace`, `delete`).
Code Example
javascript
const collection = db.collection("orders");
const changeStream = collection.watch([
{ $match: { "operationType": "insert", "fullDocument.total": { $gte: 500 } } }
]);
changeStream.on("change", (next) => {
console.log("High-value order placed!", next.fullDocument);
// Trigger real-time notifications or inventory alerts
});How It Works & Key Takeaways
Change streams provide resume tokens. If a microservice disconnects temporarily, it can reconnect using its last resume token without missing intermediate events.
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