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  1. IMPALA
  2. IMPALA-4787

Optimize APPX_MEDIAN() mem usage in case of many grouping keys

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    • Improvement
    • Status: Resolved
    • Critical
    • Resolution: Fixed
    • Impala 2.8.0
    • Impala 2.9.0
    • Backend

    Description

      APPX_MEDIAN uses a lot of memory per grouping key. It allocates space for 20,000 samples per grouping key to estimate the median. The current implementation targeted towards non-grouping aggregations or aggregations with relatively few distinct grouping keys.

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              tarasbob Taras Bobrovytsky
              szama_impala_6295 Marcell Szabo
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                Updated:
                Resolved: