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  1. Hadoop Common
  2. HADOOP-3226

Run combiner when merging spills from map output

    Details

    • Type: Improvement
    • Status: Closed
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: None
    • Fix Version/s: 0.18.0
    • Component/s: None
    • Labels:
      None
    • Hadoop Flags:
      Incompatible change, Reviewed
    • Release Note:
      Hide
      Changed policy for running combiner. The combiner may be run multiple times as the map's output is sorted and merged. Additionally, it may be run on the reduce side as data is merged. The old semantics are available in Hadoop 0.18 if the user calls:
      job.setCombineOnlyOnce(true);
      Show
      Changed policy for running combiner. The combiner may be run multiple times as the map's output is sorted and merged. Additionally, it may be run on the reduce side as data is merged. The old semantics are available in Hadoop 0.18 if the user calls: job.setCombineOnlyOnce(true);

      Description

      When merging spills from the map, running the combiner should further diminish the volume of data we send to the reduce.

        Attachments

        1. 3226-3.patch
          13 kB
          Chris Douglas
        2. 3226-2.patch
          15 kB
          Chris Douglas
        3. 3226-1.patch
          15 kB
          Chris Douglas
        4. 3226-0.patch
          2 kB
          Chris Douglas

          Activity

            People

            • Assignee:
              chris.douglas Chris Douglas
              Reporter:
              chris.douglas Chris Douglas
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              Dates

              • Created:
                Updated:
                Resolved: