choi woo cheol created PARQUET-407:
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Summary: Incorrect delta-encoding example
Key: PARQUET-407
URL: https://issues.apache.org/jira/browse/PARQUET-407
Project: Parquet
Issue Type: Improvement
Components: parquet-format
Reporter: choi woo cheol
Priority: Trivial
The minimum and the number of bits are incorrect at delta encoding Example 2 In
{{Encodings.md}}.
In the example,
{code}
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)
{code}
The minimum is -2 and the relative deltas are 0, 0, 0, 3, 3, 3, 3. So, this
should be corrected as below:
{code}
block -2 (minimum delta), 2 (bitwidth), 00000011111111b (0,0,0,3,3,3,3 packed
on 2 bits)
{code}
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