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Posted to dev@parquet.apache.org by "ASF GitHub Bot (Jira)" <ji...@apache.org> on 2020/07/16 20:29:00 UTC
[jira] [Updated] (PARQUET-1878) [C++] lz4 codec is not compatible
with Hadoop Lz4Codec
[ https://issues.apache.org/jira/browse/PARQUET-1878?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
ASF GitHub Bot updated PARQUET-1878:
------------------------------------
Labels: pull-request-available (was: )
> [C++] lz4 codec is not compatible with Hadoop Lz4Codec
> ------------------------------------------------------
>
> Key: PARQUET-1878
> URL: https://issues.apache.org/jira/browse/PARQUET-1878
> Project: Parquet
> Issue Type: Improvement
> Components: parquet-cpp
> Reporter: Steve M. Kim
> Priority: Major
> Labels: pull-request-available
> Time Spent: 10m
> Remaining Estimate: 0h
>
> As described in HADOOP-12990, the Hadoop {{Lz4Codec}} uses the lz4 block format, and it prepends 8 extra bytes before the compressed data. I believe that lz4 implementation in parquet-cpp also uses the lz4 block format, but it does not prepend these 8 extra bytes.
>
> Using Java parquet-mr, I wrote a Parquet file with lz4 compression:
> {code:java}
> $ parquet-tools meta /tmp/f4a1c7f57cb1c98c2b9da3b25b16d027df5d2f1cf55adb79374c154fbd79011f
> file: file:/tmp/f4a1c7f57cb1c98c2b9da3b25b16d027df5d2f1cf55adb79374c154fbd79011f
> creator: parquet-mr version 1.10.1 (build a89df8f9932b6ef6633d06069e50c9b7970bebd1)file schema:
> --------------------------------------------------------------------------------
> c1: REQUIRED INT64 R:0 D:0
> c0: REQUIRED BINARY R:0 D:0
> v0: REQUIRED INT64 R:0 D:0row group 1: RC:5007 TS:28028 OFFSET:4
> --------------------------------------------------------------------------------
> c1: INT64 LZ4 DO:0 FPO:4 SZ:24797/25694/1.04 VC:5007 ENC:DELTA_BINARY_PACKED ST:[min: 1566330126476659000, max: 1571211622650188000, num_nulls: 0]
> c0: BINARY LZ4 DO:0 FPO:24801 SZ:279/260/0.93 VC:5007 ENC:PLAIN,RLE_DICTIONARY ST:[min: 0x7471732F62656566616C6F2F746F6D6163636F2D66782D6D6B74646174612D6C69766573747265616D, max: 0x7471732F62656566616C6F2F746F6D6163636F2D66782D6D6B74646174612D6C69766573747265616D, num_nulls: 0]
> v0: INT64 LZ4 DO:0 FPO:25080 SZ:1348/2074/1.54 VC:5007 ENC:PLAIN,RLE_DICTIONARY ST:[min: 0, max: 9, num_nulls: 0] {code}
> When I attempted to read this file with parquet-cpp, I got the following error:
> {code:java}
> >>> import pyarrow.parquet as pq
> >>> pq.read_table('/tmp/f4a1c7f57cb1c98c2b9da3b25b16d027df5d2f1cf55adb79374c154fbd79011f')
> Traceback (most recent call last):
> File "<stdin>", line 1, in <module>
> File "/home/skim/miniconda3/envs/arrow/lib/python3.8/site-packages/pyarrow/parquet.py", line 1536, in read_table
> return pf.read(columns=columns, use_threads=use_threads,
> File "/home/skim/miniconda3/envs/arrow/lib/python3.8/site-packages/pyarrow/parquet.py", line 1260, in read
> table = piece.read(columns=columns, use_threads=use_threads,
> File "/home/skim/miniconda3/envs/arrow/lib/python3.8/site-packages/pyarrow/parquet.py", line 707, in read
> table = reader.read(**options)
> File "/home/skim/miniconda3/envs/arrow/lib/python3.8/site-packages/pyarrow/parquet.py", line 336, in read
> return self.reader.read_all(column_indices=column_indices,
> File "pyarrow/_parquet.pyx", line 1130, in pyarrow._parquet.ParquetReader.read_all
> File "pyarrow/error.pxi", line 100, in pyarrow.lib.check_status
> OSError: IOError: Corrupt Lz4 compressed data. {code}
>
> [https://github.com/apache/arrow/issues/3491] reported incompatibility in the other direction, using Spark (which uses the Hadoop lz4 codec) to read a parquet file that was written with parquet-cpp.
>
> Given that the Hadoop lz4 codec has long been in use, and users have accumulated Parquet files that were written with this implementation, I propose changing parquet-cpp to match the Hadoop implementation.
>
> See also:
> * https://issues.apache.org/jira/browse/PARQUET-1241?focusedCommentId=16574328#comment-16574328
> * https://issues.apache.org/jira/browse/PARQUET-1241?focusedCommentId=16585288#comment-16585288
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