Re: Is watermark used by joining two streams

Posted by Fabian Hueske-2 on
URL: http://deprecated-apache-flink-user-mailing-list-archive.369.s1.nabble.com/Is-watermark-used-by-joining-two-streams-tp14513p14530.html

Periodic and punctuated watermarks only differ in the way that they are generated. Afterwards they are treated the same.

An operator with two input streams will always sync its own watermarks to the watermarks of both input streams, i.e., to the "slower" watermark of both inputs.

So if the left input says it is 12:14 and the right says it is 11:53, the operator will have a internal time of 11:53 and emit watermarks according to that time.

Hope that helps,

Fabian

2017-07-28 15:00 GMT+02:00 xie wei <[hidden email]>:

Hello,

i want to join two streams based on event time window, every stream has its own watermark, one has priodic watermark and the other has punctuated watermark.

are the watermarks used to trigger the join? if yes, which one and how is it used?

Thank you and best regards

Wei