Databases & System Design•Part 3: NoSQL & Document Databases (MongoDB, DynamoDB) (26 - 40)
Write Concerns & Read Concerns:
In Simple Words:
- Write Concern (
w: "majority"): Waits for a majority of replica nodes to commit before acknowledging. - Read Concern (
"majority"): Reads only data committed by a majority of nodes to avoid dirty reads.
javascript
await db.collection('payments').insertOne(
{ transactionId: "txn_789", amount: 1000 },
{ writeConcern: { w: "majority", wtimeout: 5000 } }
);