How do you ensure the integrity of transactions in MongoDB?

Official answer

State the invariant explicitly, such as reserving stock only when enough remains and creating exactly one matching order. A transaction groups database changes atomically, but it does not decide whether the application logic is correct.

Use a supported replica-set or sharded deployment and a driver session. Pass the same session to each participating operation, check conditional-update results, and abort on a failed business precondition. A swallowed exception or unchecked zero-row update can otherwise let invalid work commit.

Choose appropriate transaction read concern and commit write concern. Snapshot reads provide a consistent snapshot under their documented conditions; they should not be described as universal serializable isolation. Enforce uniqueness and conflicting business decisions with suitable constraints and conditional writes.

Use documented retry handling for transient transaction errors and unknown commit outcomes. Callbacks may repeat, so external payments/emails need idempotent delivery and reconciliation outside the transaction. Keep transactions short and avoid unsupported parallel operations within one session.

Test concurrent reservations, duplicates, aborts, conflicts and lost commit acknowledgments. Track completion latency, conflict/retry rates and invariant violations; user engagement counts do not verify transaction integrity.

MongoDB transaction APIs, transactions