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
  

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