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Posted to issues@arrow.apache.org by "Ji Xu (JIRA)" <ji...@apache.org> on 2018/12/06 07:30:00 UTC

[jira] [Created] (ARROW-3947) query distinct values of a given partition from a ParquetDataset

Ji Xu created ARROW-3947:
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             Summary: query distinct values of a given partition from a ParquetDataset
                 Key: ARROW-3947
                 URL: https://issues.apache.org/jira/browse/ARROW-3947
             Project: Apache Arrow
          Issue Type: New Feature
          Components: Python
    Affects Versions: 0.10.0
         Environment: MacOSX, Python 3.6, 
            Reporter: Ji Xu


Right now the values of a given partition from a `ParquetDataset` is buried inside `ParquetDataset.pieces`, a bit inconvenient for the user to dig out this information. A helper function/method to perform this task in `ParquetDataset` class would be very helpful for the users.

A pure personal opinion on the name of this method: `ParquetDataset.select_distinct()` with partition_name as the positional arg, to resemble SQL `SELECT DISTINCT column FROM table`.

I'm not sure how to contribute here on Jira, so I created this [GitHub Gist |https://gist.github.com/xujiboy/c3fcc47f720ed9adf2260c5d0ba8aed2]as an possible solution for this problem.



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