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  1. IMPALA
  2. IMPALA-4787

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

    Details

    • Type: Improvement
    • Status: Resolved
    • Priority: Critical
    • Resolution: Fixed
    • Affects Version/s: Impala 2.8.0
    • Fix Version/s: Impala 2.9.0
    • Component/s: Backend
    • Labels:

      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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              • Assignee:
                tarasbob Taras Bobrovytsky
                Reporter:
                szama_impala_6295 Marcell Szabo
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                • Created:
                  Updated:
                  Resolved: