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  1. Hive
  2. HIVE-12492

MapJoin: 4 million unique integers seems to be a probe plateau

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    Details

    • Type: Improvement
    • Status: Closed
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: 1.2.1, 1.3.0, 2.0.0
    • Fix Version/s: 2.2.0
    • Component/s: Query Planning
    • Labels:
    • Target Version/s:

      Description

      After 4 million keys, the map-join implementation seems to suffer from a performance degradation.

      The hashtable build & probe time makes this very inefficient, even if the data is very compact (i.e 2 ints).

      Falling back onto the shuffle join or bucket map-join is useful after 2^22 items.

      (Note: this fixes a statsutil issue - due to the extra clone() in the column stats path)

        Attachments

        1. HIVE-12492.01.patch
          77 kB
          Jesus Camacho Rodriguez
        2. HIVE-12492.02.patch
          39 kB
          Jesus Camacho Rodriguez
        3. HIVE-12492.patch
          32 kB
          Jesus Camacho Rodriguez

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              • Assignee:
                jcamachorodriguez Jesus Camacho Rodriguez
                Reporter:
                gopalv Gopal Vijayaraghavan
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                • Created:
                  Updated:
                  Resolved: