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Posted to issues@spark.apache.org by "Max Moroz (JIRA)" <ji...@apache.org> on 2016/06/25 08:28:41 UTC

[jira] [Created] (SPARK-16207) order guarantees for DataFrames

Max Moroz created SPARK-16207:
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             Summary: order guarantees for DataFrames
                 Key: SPARK-16207
                 URL: https://issues.apache.org/jira/browse/SPARK-16207
             Project: Spark
          Issue Type: Documentation
          Components: Spark Core
    Affects Versions: 1.6.1
            Reporter: Max Moroz


There's no clear explanation in the documentation about what guarantees are available for the preservation of order in DataFrames. Different blogs, SO answers, and posts on course websites suggest different things. It would be good to provide clarity on this.

Examples of questions on which I could not find clarification:
1) Does groupby() preserve order?
2) Does take() preserve order?
3) Is DataFrame guaranteed to have the same order of lines as the text file it was read from? (Or as the json file, etc.)




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