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Posted to dev@parquet.apache.org by "Wes McKinney (JIRA)" <ji...@apache.org> on 2018/08/04 15:36:00 UTC

[jira] [Updated] (PARQUET-1370) [C++] Read consecutive column chunks in a single scan

     [ https://issues.apache.org/jira/browse/PARQUET-1370?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Wes McKinney updated PARQUET-1370:
----------------------------------
    Summary: [C++] Read consecutive column chunks in a single scan  (was: Read consecutive column chunks in a single scan)

> [C++] Read consecutive column chunks in a single scan
> -----------------------------------------------------
>
>                 Key: PARQUET-1370
>                 URL: https://issues.apache.org/jira/browse/PARQUET-1370
>             Project: Parquet
>          Issue Type: Improvement
>          Components: parquet-cpp
>            Reporter: Robert Gruener
>            Priority: Major
>
> Currently parquet-cpp calls for a filesystem scan with every single data page see [https://github.com/apache/parquet-cpp/blob/a0d1669cf67b055cd7b724dea04886a0ded53c8f/src/parquet/column_reader.cc#L181]
> For remote filesystems this can be very inefficient when reading many small columns. The java implementation already does this and will read consecutive column chunks (and the resulting pages) in a single scan see [https://github.com/apache/parquet-mr/blob/master/parquet-hadoop/src/main/java/org/apache/parquet/hadoop/ParquetFileReader.java#L786]
>  
> This might be a bit difficult to do, as it would require changing a lot of the code structure but it would certainly be valuable for workloads concerned with optimal read performance.



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