Actually, BoundedOutOfOrderWatermarkGenerator is only used in tests, the real WatermarkGenerator is code generated in WatermarkGeneratorCodeGenerator
lec ssmi <shicheng31...@gmail.com> 于2020年4月17日周五 下午5:19写道： > I think you are all right. I have I checked the source code of > WatermarkAssignerOperator, and I have found the WatermarkGenerator passed > in WatermarkAssignerOperator is the interface WatermarkGenerator. And > BoundedOutOfOrderWatermarkGenerator is the only implementation class of > WatermarkGenerator. By the way , the interval is based processing time . > > Benchao Li <libenc...@gmail.com> 于2020年4月17日周五 下午5:06写道： > >> WatermarkAssignerOperator is an inner mechanism for generating watermarks. >> >> The "Bounded Out of Orderness" is just one kind of the watermark >> expressions, which >> is most commonly used. >> >> The main logic of WatermarkAssignerOperator is: >> - keep currentWatermark and lastWatermark >> - when each element comes in >> - get watermark from this element, using the *watermark expression* >> - if the watermark > currentWatermark, then currentWatermark is updated >> - if currentWatermark - lastWatermark > watermarkInterval >> - emit watermark to downstream, and update lastWatermark >> >> lec ssmi <shicheng31...@gmail.com> 于2020年4月17日周五 下午4:50写道： >> >>> Maybe you are all right. I was more confused . >>> As the cwiki said, flink could use BoundedOutOfOrderTimestamps , >>> [image: image.png] >>> >>> but I have heard about WatermarkAssignerOperator from Blink developers. >>> >>> Benchao Li <libenc...@gmail.com> 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 <shicheng31...@gmail.com> 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:+86-15650713730 >>>> Email: libenc...@gmail.com; libenc...@pku.edu.cn >>>> >>>> >> >> -- >> >> Benchao Li >> School of Electronics Engineering and Computer Science, Peking University >> Tel:+86-15650713730 >> Email: libenc...@gmail.com; libenc...@pku.edu.cn >> >> -- Benchao Li School of Electronics Engineering and Computer Science, Peking University Tel:+86-15650713730 Email: libenc...@gmail.com; libenc...@pku.edu.cn
