[jira] [Created] (SPARK-30941) PySpark Row can be instantiated with duplicate field names

["David Roher (Jira)" <ji...@apache.org>]

David Roher created SPARK-30941:
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             Summary: PySpark Row can be instantiated with duplicate field names
                 Key: SPARK-30941
                 URL: https://issues.apache.org/jira/browse/SPARK-30941
             Project: Spark
          Issue Type: Bug
          Components: PySpark
    Affects Versions: 2.4.4
         Environment: Ubuntu 18.04

Python 3.6.8

Spark 2.4.4 (installed via binary from website)

 
            Reporter: David Roher


It is possible to create a Row that has fields with the same name when calling `collect()` after a join. Given that the Row constructor itself doesn't allow this, this seems to be undesired behavior.

This can possibly cause correctness issues because different ways of getting values produce different results: {{__getitem__}} will return the leftmost value, while {{asDict()}} will return the rightmost value (because the former uses an index search and the latter uses a dictionary generator).

{{>>> manual_output_row = Row(a=1, b=1, b=2)}}
{{ File "<stdin>", line 1}}
{{SyntaxError: keyword argument repeated}}

{{>>> input_rows = Row(a=1, b=1), Row(a=1, b=2)}}
{{>>> df1, df2 = (spark.createDataFrame([r]) for r in input_rows)}}
{{>>> df3 = df1.join(df2, "a")}}
{{>>> output_row = df3.collect()[0]}}
{{>>> output_row}}
{{Row(a=1, b=1, b=2)}}
{{>>> output_row["b"]}}
{{1}}
{{>>> output_row.asDict()["b"]}}
{{2}} 



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