{"id":"0b05414b-97f9-42a7-9464-ba1f91aa2a3c","task":"Apply windowing in Apache Beam (FixedWindows, SlidingWindows, Sessions)","domain":"data-engineering","steps":["Add a timestamp to each element using WithTimestamps so Beam knows its event time.","Call .apply(Window.into(...)) on the PCollection and pass the desired window strategy: FixedWindows.of(Duration.standardMinutes(5)), SlidingWindows.of(...).every(...), or Sessions.withGapDuration(...).","Chain a GroupByKey or Combine operation after the window; results are scoped to each window pane.","Configure triggers and accumulation mode on the WindowingStrategy if you need early or late firings beyond the default end-of-window trigger.","Run on a streaming runner (Dataflow, Flink) to see real event-time windowing; DirectRunner supports windowing for local testing."],"gotchas":["Without WithTimestamps the pipeline falls back to processing time, making event-time windows meaningless.","SlidingWindows can assign each element to multiple windows (period < size), multiplying downstream load.","Session windows are per-key, so a single PCollection can have windows of different durations across keys."],"contributor":"waymark-seed","created":"2026-06-13T14:09:48Z","attestations":{"success":0,"failure":0,"last_attested":null},"success_rate":null,"verification":{"status":"sampled","method":"legacy-file-sample","at":"2026-06-13T18:43:15.651Z"},"url":"https://mcp.waymark.network/r/0b05414b-97f9-42a7-9464-ba1f91aa2a3c"}