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  1. Spark
  2. SPARK-6026

Eliminate the bypassMergeThreshold parameter and associated hash-ish shuffle within the Sort shuffle code

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    Details

    • Type: Bug
    • Status: Resolved
    • Priority: Major
    • Resolution: Incomplete
    • Affects Version/s: 1.3.0
    • Fix Version/s: None
    • Component/s: Shuffle, Spark Core
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      Description

      The bypassMergeThreshold parameter (and associated use of a hash-ish shuffle when the number of partitions is less than this) is basically a workaround for SparkSQL, because the fact that the sort-based shuffle stores non-serialized objects is a deal-breaker for SparkSQL, which re-uses objects. Once the sort-based shuffle is changed to store serialized objects, we should never be secretly doing hash-ish shuffle even when the user has specified to use sort-based shuffle (because of its otherwise worse performance).

      Reynold XinAaron Davidson, masters of shuffle, it would be helpful to get agreement from you on this proposal (and also a sanity check that I've correctly characterized the issue).

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              • Assignee:
                Unassigned
                Reporter:
                kayousterhout Kay Ousterhout
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                • Created:
                  Updated:
                  Resolved: