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From aljoscha <...@git.apache.org>
Subject [GitHub] flink pull request: [FLINK-3336] Add Semi-Rebalance Data Shipping ...
Date Thu, 04 Feb 2016 19:59:03 GMT
Github user aljoscha commented on a diff in the pull request:

    https://github.com/apache/flink/pull/1589#discussion_r51929032
  
    --- Diff: flink-streaming-java/src/main/java/org/apache/flink/streaming/api/datastream/DataStream.java
---
    @@ -443,6 +443,35 @@ public ExecutionConfig getExecutionConfig() {
     	}
     
     	/**
    +	 * Sets the partitioning of the {@link DataStream} so that the output elements
    +	 * are distributed evenly to a subset of instances of the next operation in a round-robin
    +	 * fashion.
    +	 *
    +	 * <p>The subset of downstream operations to which the upstream operation sends
    +	 * elements depends on the degree of parallelism of both the upstream and downstream
operation.
    +	 * For example, if the upstream operation has parallelism 2 and the downstream operation
    +	 * has parallelism 4, then one upstream operation would distribute elements to two
    +	 * downstream operations while the other upstream operation would distribute to the
other
    +	 * two downstream operations. If, on the other hand, the downstream operation has parallelism
    +	 * 2 while the upstream operation has parallelism 4 then two upstream operations will
    +	 * distribute to one downstream operation while the other two upstream operations will
    +	 * distribute to the other downstream operations.
    +	 *
    +	 * <p>In cases where the different parallelisms are not multiples of each other
one or several
    +	 * downstream operations will have a differing number of inputs from upstream operations.
    +	 *
    +	 * <p>
    --- End diff --
    
    Ah, I just copied it. It's like this in all the data shipping methods. I think we could
also just get rid of this sentence, it does not really add explanation.


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