;exactly-once semantics&rdquo;, what we mean is that each incoming event affects the final results exactly once. Even in case of a machine or software failure, there&rsquo;s no duplicate data and no data that goes unprocessed.</p>
<p>Flink has long provided exactly-once semantics <em>within</em> a Flink application. Over the past few years, we&rsquo;ve <a href="https://data-artisans.com/blog/high-throughput-low-latency-and-exactly-once-stream-processing-with-apache-flink">written in depth about Flink&rsquo;