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  1. IMPALA
  2. IMPALA-5004

Switch to sorting node for large TopN queries

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Details

    • Improvement
    • Status: Resolved
    • Major
    • Resolution: Fixed
    • Impala 2.9.0
    • Impala 3.1.0
    • Frontend
    • None

    Description

      As explained by Tim Armstrong in IMPALA-4995:

      We should also consider switching to the sort operator for large limits. This allows it to spill. The memory requirements for TopN also are problematic for large limits, since it would allocate large vectors that are untracked and also require a large amount of contiguous memory.

      There's already logic to select TopN vs. Sort: planner/SingleNodePlanner.java#L289

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            stakiar Sahil Takiar
            lv Lars Volker
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