MongoDB Multi-Document Transactions

Guarantee consistency with ACID transactions across multiple operations.

Quick Start

Basic Transaction

const session = client.startSession()

try {
  await session.withTransaction(async () => {
    // All operations here are atomic
    await users.insertOne({ name: 'John' }, { session })
    await accounts.insertOne({ userId: 'xxx', balance: 100 }, { session })

    // If any fails, ALL roll back
  })
} catch (error) {
  console.error('Transaction failed:', error)
} finally {
  await session.endSession()
}

Real-World: Money Transfer

async function transferMoney(fromId, toId, amount) {
  const session = client.startSession()

  try {
    await session.withTransaction(async () => {
      // Deduct from account A
      await accounts.updateOne(
        { _id: fromId },
        { $inc: { balance: -amount } },
        { session }
      )

      // Add to account B
      await accounts.updateOne(
        { _id: toId },
        { $inc: { balance: amount } },
        { session }
      )

      // Both succeed, or both rollback - NO PARTIAL TRANSFERS!
    })
  } catch (error) {
    // Transaction failed, money not transferred
    console.error('Transfer failed:', error)
  } finally {
    await session.endSession()
  }
}

Transaction Requirements

MongoDB Version

• MongoDB 4.0+: Single-document transactions (all versions)
• MongoDB 4.0: Multi-document transactions (replica sets)
• MongoDB 4.2+: Multi-document transactions (sharded clusters)

Deployment Type

• Replica Set: Required for transactions
• Sharded Cluster: MongoDB 4.2+
• Standalone: Single-document transactions only
• Atlas Free: No transactions (shared clusters)

Session Management

Create Session

const session = client.startSession()

// Configure session
const session = client.startSession({
  defaultTransactionOptions: {
    readConcern: { level: 'snapshot' },
    w...