Hi, There's a Flink SQL Cookbook recipe on CURRENT_WATERMARK, I think this would cover your questions [1].
Best regards, Martijn [1] https://github.com/ververica/flink-sql-cookbook/blob/main/other-builtin-functions/03_current_watermark/03_current_watermark.md On Fri, 11 Feb 2022 at 16:45, M Singh <mans2si...@yahoo.com> wrote: > 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 > > > >
