How to avoid consuming duplicate messages in RocketMQ?

In order to prevent duplicate message consumption in RocketMQ, the following methods can be employed:

1. Set a unique identifier for messages: When a producer sends a message, assign a unique message ID to each message. When consumers receive the message, they can first check if the message ID has already been processed. If it has, the message will not be consumed. This method requires ensuring the uniqueness of message IDs.
2. Persistence of consumption progress: RocketMQ offers the functionality of storing consumer consumption progress, allowing consumers to store their consumption progress in a database or other storage medium. When receiving a message, consumers first check the consumption progress of the message, and if it has already been consumed, no further consumption is carried out. This method ensures that even if the consumer restarts or fails, it can continue consuming from the last consumed position.
3. Idempotent processing: Ensures that repeated consumption of the same message in the consumer’s message processing business logic will not have any impact, achieving idempotence. This can be achieved by adding a unique constraint in the database or using distributed locks.
4. Consumer group model: By grouping multiple consumers into a consumer cluster to consume messages, RocketMQ will automatically perform load balancing. When a consumer processes a message, other consumers will automatically ignore that message, avoiding duplicate consumption.

In practical use, you can choose the appropriate way to avoid duplicate consumption of RocketMQ messages based on the specific business scenario.