Transactions — MongoDB Tutorial

Multi-Document Transactions

Transactions let you execute multiple operations atomically — either all succeed or all fail. This is essential for operations that must be consistent across documents.

Example

const session = await mongoose.startSession();

try {
  session.startTransaction();

  // Transfer money between accounts
  await Account.updateOne(
    { _id: senderId },
    { $inc: { balance: -amount } },
    { session }
  );

  await Account.updateOne(
    { _id: receiverId },
    { $inc: { balance: amount } },
    { session }
  );

  // Record the transfer
  await Transfer.create([{
    from: senderId,
    to: receiverId,
    amount,
    date: new Date()
  }], { session });

  await session.commitTransaction();
  console.log('Transfer successful');
} catch (error) {
  await session.abortTransaction();
  console.error('Transfer failed:', error);
} finally {
  session.endSession();
}

When to Use Transactions

Transactions add overhead, so use them only when atomicity across documents is required.

Financial operations (transfers, payments)
Inventory management (order + stock update)
User registration (create user + profile + settings)
Any operation where partial completion would leave data inconsistent