Message Deduplication and Exactly‑Once Semantics in RocketMQ
This article explains why RocketMQ guarantees at‑least‑once delivery, describes the three typical duplicate‑message scenarios, compares transaction‑based and non‑transactional deduplication approaches (including a Redis‑based solution), provides sample SQL and Java code, and discusses the limitations and best‑practice recommendations for achieving idempotent message consumption.