Transactions in MongoDB

8 min read

Multi-Document Transactions

MongoDB supports ACID multi-document transactions on replica sets and sharded clusters (version 4.0+). Transactions let you group multiple operations so they either all succeed or all roll back — essential for operations like transferring credits between accounts.

import { MongoClient } from "mongodb";

const client = new MongoClient(process.env.MONGODB_URI);
await client.connect();

const session = client.startSession();

try {
  session.startTransaction();

  const db = client.db("school");
  await db.collection("students").updateOne(
    { name: "Riya Sharma" },
    { $set: { enrolled: true } },
    { session }
  );
  await db.collection("payments").insertOne(
    { studentName: "Riya Sharma", amount: 15000, paidAt: new Date() },
    { session }
  );

  await session.commitTransaction();
} catch (err) {
  await session.abortTransaction();
  throw err;
} finally {
  await session.endSession();
  await client.close();
}

Transactions add latency and resource overhead. Use them only when you genuinely need atomicity across multiple collections. For single-document operations, MongoDB is already atomic without a transaction.

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