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  1. Hive
  2. HIVE-7428

OrcSplit fails to account for columnar projections in its size estimates

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Details

    • Bug
    • Status: Resolved
    • Major
    • Resolution: Duplicate
    • 1.2.0, 1.3.0, 2.0.0
    • None
    • None
    • None
    • Estimate columnar projection when generating ORC splits

    Description

      Currently, ORC generates splits based on stripe offset + stripe length.

      This means that the splits for all columnar projections are exactly the same size, despite reading the footer which gives the estimated sizes for each column.

      This is a hold-out from FileSplit which uses getLen() as the I/O cost of reading a file in a map-task.

      RCFile didn't have a footer with column statistics information, but for ORC this would be extremely useful to reduce task overheads when processing extremely wide tables with highly selective column projections.

      Attachments

        1. HIVE-7428.1.patch
          7 kB
          Prasanth Jayachandran
        2. HIVE-7428.2.patch
          8 kB
          Gopal Vijayaraghavan

        Issue Links

          is blocked by

          Improvement - An improvement or enhancement to an existing feature or task. HIVE-10497 Upgrade hive branch to latest Tez

          • Major - Major loss of function.
          • Resolved
          is duplicated by

          Sub-task - The sub-task of the issue HIVE-10397 LLAP: Implement Tez SplitSizeEstimator for Orc

          • Major - Major loss of function.
          • Resolved
          relates to

          Bug - A problem which impairs or prevents the functions of the product. HIVE-11546 Projected columns read size should be scaled to split size for ORC Splits

          • Major - Major loss of function.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. TEZ-1993 Implement a pluggable InputSizeEstimator for grouping fairly

          • Major - Major loss of function.
          • Closed
          supercedes

          Sub-task - The sub-task of the issue HIVE-10397 LLAP: Implement Tez SplitSizeEstimator for Orc

          • Major - Major loss of function.
          • Resolved

          Activity

            People

              gopalv Gopal Vijayaraghavan
              gopalv Gopal Vijayaraghavan
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              Dates

                Created:
                Updated:
                Resolved: