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From xccui <...@git.apache.org>
Subject [GitHub] flink issue #5094: [FLINK-8158] [table] Fix rowtime window inner join emits ...
Date Wed, 29 Nov 2017 04:27:05 GMT
Github user xccui commented on the issue:

    https://github.com/apache/flink/pull/5094
  
    Hi @hequn8128, let me try to explain this.
    
    1. In current implementation,  the join process just relies on the cached rows instead
of the watermarks. Specifically, when receiving a record, the join function will only check
whether there exist qualified rows of the opposite cache in spite of the lateness. Thus if
the cache ***is not cleaned up in time***, the outdated results will be emitted.
    
    2. Strictly speaking, the value for holding back watermarks should be dynamically reported
by the join function in runtime. The current implementation temporarily uses a static value
(`MaxOutputDelay`) for that. In other words, the holding back value should be decided by the
cached rows, rather than, the cache size should be decided by `MaxOutputDelay`.
    
    Hope that helps.
    
    Best, Xingcan


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