[PARQUET-2089] [C++] RowGroupMetaData file_offset set incorrectly

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: cpp-6.0.0
• Component/s: parquet-cpp
• Labels: pull-request-available
• Assignee: Micah Kornfield
• Reporter: Archie Menzies
• Created: 11/Aug/21 15:52
• Updated: 22/Sep/21 07:04
• Resolved: 22/Sep/21 07:04

Description

It appears that the RowGroupMetaData file_offset property is being set to the same value as the first ColumnMetaData file_offset property in https://github.com/apache/arrow/blob/8e43f23dcc6a9e630516228f110c48b64d13cec6/cpp/src/parquet/metadata.cc#L1557-L1565

 

This is not consistent with the definition of these properties given in the Thrift file: https://github.com/apache/arrow/blob/master/cpp/src/parquet/parquet.thrift

struct ColumnChunk {
  ...

  /** Byte offset in file_path to the ColumnMetaData **/
  2: required i64 file_offset
  
  ...
}

...

struct RowGroup {
  ...

  /** Byte offset from beginning of file to first page (data or dictionary)
   * in this row group **/
  5: optional i64 file_offset

  ...
}

This is causing issues when trying to read the file with the parquet-mr libraries, because the RowGroup's file offset is used to determine whether a RowGroup exists within a given file split: https://github.com/apache/parquet-mr/blob/master/parquet-hadoop/src/main/java/org/apache/parquet/format/converter/ParquetMetadataConverter.java#L1226-L1251

 

This issue is therefore resulting in Parquet files which cannot be read as the metadata is incorrect.

Issue Links

• links to: GitHub Pull Request #11149