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[Table API/SQL] Finding missing spots to resolve why 'no watermark' is presented in Flink UI


Hi Flink users,

I'm new to Flink and trying to evaluate couple of streaming frameworks via implementing same apps.

While implementing apps with both Table API and SQL, I found there's 'no watermark' presented in Flink UI, whereas I had been struggling to apply row time attribute.

For example, below is one of TableSource implementation which wraps DataStream reading from Kafka.

https://github.com/HeartSaVioR/iot-trucking-app-flink/blob/master/src/main/scala/net/heartsavior/flink/datasource/TruckSpeedSource.scala

(Actually I ended up implementing TableSource to address adding rowtime attribute as well as reading and parsing JSON. I'd be really happy if someone can guide a way to get rid of needed of custom implementation of TableSource.)

and below is one of app I implemented:

https://github.com/HeartSaVioR/iot-trucking-app-flink/blob/master/src/main/scala/net/heartsavior/flink/app/sql/IotTruckingAppMovingAggregationsOnSpeedSql.scala

Btw, I'm about to experiment side-output with late events, but is it possible to leverage side-output with Table API / SQL? Looks like DataStream exposes late events only when it's converted to AllWindowedStream.

Thanks in advance!

Best Regards,
Jungtaek Lim (HeartSaVioR)