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  1. Kudu
  2. KUDU-2888

Better encoding for dictionary code-words

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    Details

    • Type: Bug
    • Status: Open
    • Priority: Major
    • Resolution: Unresolved
    • Affects Version/s: None
    • Fix Version/s: None
    • Component/s: cfile, perf
    • Labels:
      None

      Description

      Currently we use bitshuffle for all ints, including dictionary codewords. For dictionary codewords, we know the maximum possible value up-front, and we also know that the ints will be non-negative and small. This set of constraints makes it much better to use a specialized bitpacking algorithm rather than a more generic compression like bitshuffle+lz4. Based on some quick experiments I ran, we can probably get a several-fold decoding speedup with no loss of compression by switching to a codec like simdbitpacking for these codewords.

        Attachments

        1. codec-test.py
          1 kB
          Todd Lipcon

          Activity

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            • Assignee:
              Unassigned
              Reporter:
              tlipcon Todd Lipcon
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              Dates

              • Created:
                Updated: