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  1. Parquet
  2. PARQUET-407

Incorrect delta-encoding example

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Details

    • Improvement
    • Status: Resolved
    • Trivial
    • Resolution: Fixed
    • None
    • format-2.4.0
    • parquet-format
    • None

    Description

      The minimum and the number of bits are incorrect at delta encoding Example 2 In Encodings.md.

      In the example,

      Example 2
      
      7, 5, 3, 1, 2, 3, 4, 5, the deltas would be
      
      -2, -2, -2, 1, 1, 1, 1
      The minimum is -2, so the relative deltas are:
      
      0, 0, 0, 3, 3, 3, 3
      
      The encoded data is
      
      header: 8 (block size), 1 (miniblock count), 8 (value count), 7 (first value)
      
      block 0 (minimum delta), 2 (bitwidth), 000000111111b (0,0,0,3,3,3 packed on 2 bits)
      

      The minimum is -2 and the relative deltas are 0, 0, 0, 3, 3, 3, 3. So, this should be corrected as below:

      block -2 (minimum delta), 2 (bitwidth), 00000011111111b (0,0,0,3,3,3,3 packed on 2 bits)
      

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            Unassigned Unassigned
            woo cheol choi woo cheol
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              Created:
              Updated:
              Resolved: