Idempotent Request

Overview

An Idempotent Request is a request that can be retried without creating an additional logical operation or unintended side effect. It is not the same as a duplicate request because a duplicate describes what happened, while idempotency describes the safety and result rules applied to repetitions.

The main risks include duplicate creation, inconsistent replayed results, simultaneous requests with the same key, and unsafe retry of uncertain operations. The property may come from the HTTP method itself or from an application mechanism such as an idempotency key.

In production, teams should define ownership and apply stable operation key, request fingerprint comparison, durable result record, concurrency control, bounded retention, and documented conflict behavior. Configuration changes to Idempotent Request should be versioned and tested under burst, timeout, dependency failure, and restart conditions.

Useful measures include idempotency hit rate, key conflict rate, duplicate operation count, and retry completion rate. Idempotent Request is closely connected to Idempotency Header, Idempotency Record, and Idempotent Processing. A Idempotent Request decision should use documented method semantics and provider error classes rather than message text alone.

The Idempotent Request implementation should bound attempts, preserve the original operation identity, and stop before retries amplify a dependency failure. Operational review of Idempotent Request should separate successful recovery from repeated attempts that only increase latency or load. Metrics for Idempotent Request should separate first-attempt success, recovered operations, exhausted attempts, duplicate prevention, and added latency.

Manual intervention for Idempotent Request should begin only after automated status checks cannot determine a safe final outcome. The Idempotent Request policy should define which failures are retryable, how long the decision remains valid, and how duplicate effects are prevented.