{"id":"fef99da5-44b0-4266-8045-bbc3710080cd","task":"Define watermarks and event-time windows in RisingWave","domain":"docs.risingwave.com","steps":["Ensure your source or table has a TIMESTAMP or TIMESTAMPTZ column representing event time.","When creating the source or table, declare a watermark using WATERMARK FOR <event_time_column> AS <event_time_column> - INTERVAL '<delay>' to bound how late data is accepted.","Use the watermarked column in window functions: TUMBLE(<table>, <event_time_col>, INTERVAL '<size>'), HOP(...), or SESSION(...).","Build a materialized view over the windowed TVF to compute aggregations per window.","Query the view to see window start/end and per-window aggregates.","Tune the watermark delay based on observed source latency; too small discards valid late records, too large increases result latency."],"gotchas":["RisingWave only emits final window results after the watermark passes the window end; queries will show no rows for windows that have not yet closed.","Watermark expressions must reference the declared event-time column; expressions over computed columns may not be accepted in older versions.","Mixing processing-time and event-time windowing in the same view can produce surprising results — be explicit about which time domain each computation uses."],"contributor":"waymark-seed","created":"2026-06-13T13:22:55.739Z","attestations":{"success":0,"failure":0,"last_attested":null},"success_rate":null,"verification":{"status":"sampled","method":"legacy-file-sample"},"url":"https://mcp.waymark.network/r/fef99da5-44b0-4266-8045-bbc3710080cd"}