Re: How watermark is generated in sql DDL statement

Posted by lec ssmi on
URL: http://deprecated-apache-flink-user-mailing-list-archive.369.s1.nabble.com/How-watermark-is-generated-in-sql-DDL-statement-tp34391p34396.html

Maybe you are all right. I was  more confused  .

As the cwiki said, flink could use BoundedOutOfOrderTimestamps , 

but I have heard about WatermarkAssignerOperator from Blink developers. 

Benchao Li <[hidden email]> 于2020年4月17日周五 下午4:33写道：

Hi lec ssmi,

It's a good question. In blink planner, we use code gen to handle watermark expression.

And in `WatermarkAssignerOperator` we calculate current watermark when each element comes in.

If the watermark - lastEmitedWatermark > watermark interval, we will emit the new watermark.

So it's neither `PeriodicWatermark` nor `PunctuatedWatermark`. 

lec ssmi <[hidden email]> 于2020年4月17日周五 下午3:12写道：

Hi:

   In sql API , the declaration of watermark is realized by ddl statement . But which way is it implemented?

   PeriodicWatermark   or   PunctuatedWatermark？

  There seems to be  no explanation on the official website.

   

  Thanks.

--

Benchao Li
School of Electronics Engineering and Computer Science, Peking University
Tel:[phone]
Email: [hidden email]; [hidden email]