Popular Idempotency Articles

An idempotency key is a unique value attached to a request so a server can recognize repeated attempts to perform the same logical operation and avoid executing it more than once.

Idempotency allows the same logical operation to be executed multiple times without producing additional side effects. Deduplication identifies repeated requests, commands, or events and prevents them from being processed as new work.

Message deduplication is the process of detecting repeated deliveries of the same logical message and preventing them from producing duplicate business effects. It is a core reliability technique in message queues, event-driven systems, and distributed applications that use at-least-once delivery.

Kafka preserves record order inside a partition, not across an entire multi-partition topic. That distinction affects partition-key design, consumer concurrency, retries, scaling, and every workflow where events must be applied in a predictable sequence.

A payment request times out. The customer sees an error and presses Pay again. The first request may have failed, or it may have successfully charged the card while only the response was lost.