Wang Yangjun created FLINK-3109:
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             Summary: Join two streams with two different cache time
                 Key: FLINK-3109
                 URL: https://issues.apache.org/jira/browse/FLINK-3109
             Project: Flink
          Issue Type: Improvement
          Components: Streaming
    Affects Versions: 0.10.1
            Reporter: Wang Yangjun
             Fix For: 0.10.2


Current Flink streaming only supports join two streams on the same window. How 
to solve this problem?
For example, there are two streams. One is advertisements showed to users. The 
tuple in which could be described as (id, showed timestamp). The other one is 
click stream -- (id, clicked timestamp). We want get a joined stream, which 
includes all the advertisement that is clicked by user in 20 minutes after 
showed.
It is possible that after an advertisement is shown, some user click it 
immediately. The "click" message could arrive to server earlier than "show" 
message because of Internet delay. We assume that the maximum delay is one 
minute.

Then the need is that we should alway keep a buffer(20 mins) of "show" stream 
and another buffer(1 min) of "click" stream.

It would be grate that there is such an API like.
showStream.join(clickStream)
            .where(keySelector)
            .buffer(Time.of(20, TimeUnit.MINUTES))
            .equalTo(keySelector)
            .buffer(Time.of(1, TimeUnit.MINUTES))
            .apply(JoinFunction)

http://stackoverflow.com/questions/33849462/how-to-avoid-repeated-tuples-in-flink-slide-window-join/34024149#34024149



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