Watermark Strategies for Real Pipelines

Production watermarks are more nuanced than the textbook version. Different sources have different lateness profiles. Kafka timestamps behave differently from custom event timestamps. Multi-source pipelines need per-source watermarks merged at the join point. Watermark Strategies by Source Multi-Source Watermarks When joining two streams with different lateness profiles, the system watermark is the MINIMUM of the individual source watermarks. A fast source (Kafka, seconds late) joined with a slow source (mobile, hours late) means the joined stream's watermark is governed by the slow source. Vocabulary That Signals Seniority The Bridge Move