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https://issues.apache.org/jira/browse/SPARK-29748?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Bryan Cutler resolved SPARK-29748.
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Fix Version/s: 3.0.0
Resolution: Fixed
Issue resolved by pull request 26496
[https://github.com/apache/spark/pull/26496]
> Remove sorting of fields in PySpark SQL Row creation
> ----------------------------------------------------
>
> Key: SPARK-29748
> URL: https://issues.apache.org/jira/browse/SPARK-29748
> Project: Spark
> Issue Type: Bug
> Components: PySpark, SQL
> Affects Versions: 3.0.0
> Reporter: Bryan Cutler
> Assignee: Bryan Cutler
> Priority: Major
> Fix For: 3.0.0
>
>
> Currently, when a PySpark Row is created with keyword arguments, the fields
> are sorted alphabetically. This has created a lot of confusion with users
> because it is not obvious (although it is stated in the pydocs) that they
> will be sorted alphabetically, and then an error can occur later when
> applying a schema and the field order does not match.
> The original reason for sorting fields is because kwargs in python < 3.6 are
> not guaranteed to be in the same order that they were entered. Sorting
> alphabetically would ensure a consistent order. Matters are further
> complicated with the flag {{__from_dict__}} that allows the {{Row}} fields to
> to be referenced by name when made by kwargs, but this flag is not serialized
> with the Row and leads to inconsistent behavior.
> This JIRA proposes that any sorting of the Fields is removed. Users with
> Python 3.6+ creating Rows with kwargs can continue to do so since Python will
> ensure the order is the same as entered. Users with Python < 3.6 will have to
> create Rows with an OrderedDict or by using the Row class as a factory
> (explained in the pydoc). If kwargs are used, an error will be raised or
> based on a conf setting it can fall back to a LegacyRow that will sort the
> fields as before. This LegacyRow will be immediately deprecated and removed
> once support for Python < 3.6 is dropped.
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