[GitHub] storm pull request #2233: Storm 2258: Streams api - support CoGroupByKey

[arunmahadevan <gi...@git.apache.org>]

Github user arunmahadevan commented on a diff in the pull request:

    https://github.com/apache/storm/pull/2233#discussion_r131690416
  
    --- Diff: storm-client/src/jvm/org/apache/storm/streams/PairStream.java ---
    @@ -380,6 +383,22 @@
             return partitionBy(KEY).updateStateByKeyPartition(stateUpdater);
         }
     
    +    /**
    +     * group the values of this stream with the values having the same key from the other stream.
    --- End diff --
    
    May be here and in the Streams API doc add a snippet to make it clear:
    
    ```
    If stream1 has values - (k1, v1), (k2, v2), (k2, v3) 
    and stream2 has values - (k1, x1), (k1, x2), (k3, x3)
    
    The the co-grouped stream would contain -
    (k1, ([v1], [x1, x2]), (k2, ([v2, v3], [])), (k3, ([], [x3]))
    ```


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