[jira] [Created] (FLINK-2143) Add an overload to reduceWindow which takes the inverse of the reduceFunction as a second parameter

[Shang Yuanchun (Jira)]

Gabor Gevay created FLINK-2143:
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             Summary: Add an overload to reduceWindow which takes the inverse of the reduceFunction as a second parameter
                 Key: FLINK-2143
                 URL: https://issues.apache.org/jira/browse/FLINK-2143
             Project: Flink
          Issue Type: Sub-task
            Reporter: Gabor Gevay
            Assignee: Gabor Gevay


If the inverse of the reduceFunction is also available (for example subtraction when summing numbers), then a PreReducer can maintain the aggregate in O(1) memory and O(1) time for evict, store, and emitWindow.



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