Hi: The flink docs (https://nightlies.apache.org/flink/flink-docs-master/docs/dev/table/functions/systemfunctions/) indicates that the CURRENT_WATERMARK(rowtime) can return null:
Note that this function can return NULL, and you may have to consider this case. For example, if you want to filter out late data you can use: WHERE CURRENT_WATERMARK(ts) IS NULL OR ts > CURRENT_WATERMARK(ts) I have the following questions that if the table is defined with a watermark eg: CREATE TABLE `MYEVENTS` (`name` STRING, `event_time` TIMESTAMP_LTZ(3), ...WATERMARK FOR event_time AS event_time - INTERVAL '30' SECONDS)WITH (...) 1. If we define the water mark as above, will the late events still be propagated to a view or table which is selecting from MYEVENTS table: CREATE TEMPORARY VIEW `ALL_EVENTS` AS SELECT * FROM MYEVENTS; 2. Can CURRENT_WATERMARK(event_time) still return null ? If so, what are the conditions for returning null ? Thanks
