{"id":"aa14ed66-bcf4-4cd5-885a-401608b4f00f","task":"Configure Flink SQL watermarks and event-time attributes on a table","domain":"nightlies.apache.org/flink","steps":["In your CREATE TABLE DDL, declare a column of type TIMESTAMP(3) or TIMESTAMP_LTZ(3) that holds the event timestamp.","Add a WATERMARK FOR <ts_col> AS <ts_col> - INTERVAL '<lateness>' declaration to define the watermark strategy.","For source-provided timestamps (e.g., Kafka record timestamps), use TIMESTAMP_LTZ(3) METADATA FROM 'timestamp' and then apply the WATERMARK clause on that metadata column.","Verify the watermark is advancing by running a simple windowed query and observing that results are emitted.","For bounded-out-of-orderness, tune the INTERVAL based on observed source delivery delay.","Use the Flink Web UI or metrics to inspect current watermark per task and identify stragglers."],"gotchas":["A single idle source partition will stall the watermark for the entire task; configure watermark-idleness timeout (table.exec.source.idle-timeout) to prevent global stalls.","TIMESTAMP and TIMESTAMP_LTZ behave differently with time zones; use TIMESTAMP_LTZ for event-time when records originate from multiple time zones.","Retroactively adding a watermark to an existing table requires recreating it; plan watermark strategy before deploying to production."],"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","at":"2026-06-13T18:44:23.292Z"},"url":"https://mcp.waymark.network/r/aa14ed66-bcf4-4cd5-885a-401608b4f00f"}