Distributed Transactions and Sagas

A checkout can reserve stock and charge payment in separate services. A local database transaction cannot automatically make both owners commit together. If one step succeeds and the next fails, the product needs a truthful state and a recovery path.

First ask whether the operation can stay inside one transactional boundary. When separate ownership is justified, compare coordination and compensating workflows explicitly.

Two-phase commit coordinates participating resource managers through prepare and commit decisions. It requires compatible participants and recovery of the coordinator’s decision; failures can leave participants waiting and holding resources. It is not available for every external API.

A saga is a sequence of local transactions with defined actions to compensate earlier work when required. Other observers can see intermediate states unless the application designs around them. Prefer an explicit pending order to claiming an unfinished checkout already succeeded.

If stock was reserved but payment was rejected, release the reservation under its identity. If payment succeeded and a later step failed, the refund contract determines what can be reversed and when. Fees, external notifications and shipped goods may not be perfectly reversible.

Compensation can fail and need retry or human review. Persist each step’s state, use stable operation keys and make repeated commands safe. Keep a reconciliation process for uncertain payment results; a timeout alone is not evidence of rejection.

Evaluate consequences across the owners rather than hiding partial success.

With orchestration, a coordinator records workflow progress and issues commands. With choreography, services react to events under a shared contract. Orchestration centralizes visibility; choreography can decouple participants but make global progress harder to inspect. Neither makes duplicates or lost communication disappear.

AWS Step Functions and Temporal are workflow options with different hosting and execution semantics. Durable outboxes can connect local commits to message publication. Read AWS’s saga orchestration guidance and your workflow engine’s actual recovery contract.

Monitor pending-age, compensations and unresolved outcomes. Set deadlines for reservations and an explicit human-review path. See event-driven architecture for publication safety.

Use the Saga pattern exercise to inspect compensation and uncertainty. Outbox can protect each participant’s publication intent; Retry still needs a stable operation identity.

Keep a simple transaction boundary when it fits. When work spans owners, record progress, define compensation and resolve uncertainty before repeating effects.