title: Difference between idempotence and exactly-once in Kafka Stream
body: <p>I was going through document what I understood we can achieve exactly-once transaction with enabling <code>idempotence=true</code></p>
  
  <blockquote>
    <p>idempotence: The Idempotent producer enables exactly once for a
    producer against a single topic. Basically each single message send
    has stonger guarantees and will not be duplicated in case there's an
    error</p>
  </blockquote>
  
  <p>So if already we have idempotence then why we need another property exactly-once in Kafka Stream? What exactly different between idempotence vs exactly-once</p>
  
  <p>Why exactly-once property not available in normal Kafka Producer?</p>