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  1. IMPALA
  2. IMPALA-6178

Heuristic for selecting the left-most table should consider parallelism.

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    Details

    • Type: Improvement
    • Status: Resolved
    • Priority: Major
    • Resolution: Later
    • Affects Version/s: Impala 2.10.0, Impala 2.11.0
    • Fix Version/s: None
    • Component/s: Frontend

      Description

      For each query block, Impala uses the estimated materialized size of tables as a heuristic for choosing the left-most table in a series of joins. Unfortunately, that heuristic does not factor in the number of hosts that tables will execute on. The number of hosts of the left-most table dictates the degree of inter-node parallelism.

      To handle this tradeoff between parallelism and size we should use a heuristic like the one in IMPALA-5612.

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            • Assignee:
              Unassigned
              Reporter:
              alex.behm Alexander Behm
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              • Created:
                Updated:
                Resolved: