[jira] [Created] (HIVE-7859) Tune zlib compression in ORC to account for the encoding strategy

["Gopal V (JIRA)" <ji...@apache.org>]

Gopal V created HIVE-7859:
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             Summary: Tune zlib compression in ORC to account for the encoding strategy
                 Key: HIVE-7859
                 URL: https://issues.apache.org/jira/browse/HIVE-7859
             Project: Hive
          Issue Type: Bug
          Components: File Formats
            Reporter: Gopal V


Currently ORC Zlib is slow because several compression strategies ZLib uses is already done by ORC in itself (dictionary, RLE, bit-packing).

We need to pick between Z_FILTERED, Z_HUFFMAN_ONLY, Z_RLE, Z_FIXED and Z_DEFAULT_STRATEGY according to column stream type.

For instance an RLE_V2 stream could a use Z_FILTERED compression without invoking the rest of the strategies.

The string streams can use Z_FIXED compression strategies and so on.

The core limitation to stick to retain compatibility with the default decompressor, so that these are automatically backward compatible.



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