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  1. Hive
  2. HIVE-16274

Support tuning of NDV of columns using lower/upper bounds

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    Details

    • Type: Bug
    • Status: Resolved
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: 2.1.0
    • Fix Version/s: 2.3.0
    • Component/s: None
    • Labels:

      Description

      For partitioned tables, the distinct value (nDV) estimate for a column is by default set to the largest nDV value in any of the partitions being considered, which is a lower bound on the nDV estimate.
      This provides a config setting to allow the estimate to a specified fraction (0.0 - 1.0) of the higher bound on the nDV estimate (the sum of all the nDVs in all partitions).

        Attachments

        1. HIVE-16274.01.patch
          29 kB
          Pengcheng Xiong
        2. HIVE-16274.02.patch
          31 kB
          Pengcheng Xiong

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              • Assignee:
                pxiong Pengcheng Xiong
                Reporter:
                pxiong Pengcheng Xiong
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                  Updated:
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