How to Prevent Duplicate Messages in Kafka and Pulsar: A Practical Guide

This article explains the three message delivery semantics, the common causes of duplicate messages in queue systems, and presents concrete producer‑side, broker‑side, and consumer‑side deduplication techniques for Kafka and Pulsar, including code samples and best‑practice recommendations.

BackendIdempotenceKafka

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How to Prevent Duplicate Messages in Kafka and Pulsar: A Practical Guide

Java Tech Enthusiast

Mar 9, 2025 · Backend Development

Handling Duplicate Messages in Message Queues

Message queues can deliver duplicates under at‑least‑once semantics, so to protect idempotent business logic such as orders and payments you should combine producer‑side idempotence (e.g., Kafka’s enable.idempotence), broker‑side deduplication (e.g., Pulsar), and a consumer‑side guard using unique IDs stored in a database or Redis.

IdempotenceKafkaMessage Queue

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Handling Duplicate Messages in Message Queues