What is the difference between periodic and dotted watermarks in Apache Flink?

Question

It will be helpful if someone gives a usecase example to explain the difference between each of the Watermark APIs with the Apache flag below

• Periodic Watermarks - AssignerWithPeriodicWatermarks[T]
• AssignerWithPunctuatedWatermarks[T] water marks - AssignerWithPunctuatedWatermarks[T]

Answer 1

The main difference between the two types of watermarks is how / when the method is called getWatermark.

periodic watermark

With periodic watermarks, Flink calls getCurrentWatermark()at a regular interval regardless of the flow of events. This interval is determined using

ExecutionConfig.setAutoWatermarkInterval(millis)

, ( ) , , , - / .

Flink checkAndGetWatermark() , .. assignWatermark(). , checkAndGetWatermark , , .

, - , .

, , , . , , .