[jira] [Created] (PARQUET-251) Binary column statistics error when reuse byte[] among rows

["Yijie Shen (JIRA)" <ji...@apache.org>]

Yijie Shen created PARQUET-251:
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             Summary: Binary column statistics error when reuse byte[] among rows
                 Key: PARQUET-251
                 URL: https://issues.apache.org/jira/browse/PARQUET-251
             Project: Parquet
          Issue Type: Bug
          Components: parquet-mr
    Affects Versions: 1.6.0
            Reporter: Yijie Shen


I think it is a common practice when inserting table data as parquet file, one would always reuse the same object among rows, and if a column is byte[] of fixed length, the byte[] would also be reused. 

If I use ByteArrayBackedBinary for my byte[], the bug occurs: All of the row groups created by a single task would have the same max & min binary value, just as the last row's binary content.

The reason is BinaryStatistic just keep max & min as parquet.io.api.Binary references, since I use ByteArrayBackedBinary for byte[], the real content of max & min would always point to the reused byte[], therefore the latest row's content.

Does parquet declare somewhere that the user shouldn't reuse byte[] for Binary type?  If it doesn't, I think it's a bug and can be reproduced by [Spark SQL's RowWriteSupport |https://github.com/apache/spark/blob/master/sql/core/src/main/scala/org/apache/spark/sql/parquet/ParquetTableSupport.scala#L353-354]

The related Spark JIRA ticket: [SPARK-6859|https://issues.apache.org/jira/browse/SPARK-6859]



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