Fabrizio Milo created PARQUET-575:
-------------------------------------
Summary: Different RLE Encoding Specification
Key: PARQUET-575
URL: https://issues.apache.org/jira/browse/PARQUET-575
Project: Parquet
Issue Type: Improvement
Reporter: Fabrizio Milo
Priority: Trivial
In the parquet-format specification
https://github.com/Parquet/parquet-format/blob/master/Encodings.md#run-length-encoding--bit-packing-hybrid-rle--3
is written that the RLE encoding starts with
```
rle-bit-packed-hybrid: <length> <encoded-data>
length := length of the <encoded-data> in bytes stored as 4 bytes little endian
```
while in the cpp implementation there is this description
https://github.com/apache/parquet-cpp/blob/master/src/parquet/util/rle-encoding.h#L42
and the implementation seems to follow that specification
which does not include the initial <length> <encoded-data>
https://github.com/apache/parquet-cpp/blob/master/src/parquet/util/rle-encoding.h#L272
So which one is the correct? seems that the parquet-format is the wrong one.
DataPage.definitionLevels uses RLE and none of the example format files seem to
have that initial <length> <encoded-data>
Also the use of both names `literal` and `bit-encoding` is confusing.
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