Exactly-Once Delivery: Kafka's Inbox Pattern in Production

Duplicate message processing is a critical production risk that can cause serious data corruption—double stock deductions and duplicate orders. While Kafka transactions guarantee producer-side delivery, they don't prevent duplicate business logic execution on the consumer side. The Inbox pattern solves this by wrapping message deduplication, business logic, and state changes in a single atomic database transaction, making it essential for systems handling critical operations.