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https://issues.apache.org/jira/browse/SPARK-16207?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15900162#comment-15900162
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Sean Owen commented on SPARK-16207:
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[~rcrogers] where would you document this? we could add a document in a place
that would have helped you. However as I say, lots of things don't preserve
order, so I don't know if it's sensible to write that everywhere.
> 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
> Priority: Minor
>
> 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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