[jira] [Created] (SPARK-27134) array_distinct function does not work correctly with columns containing array of array

["Mike Trenaman (JIRA)" <ji...@apache.org>]

Mike Trenaman created SPARK-27134:
-------------------------------------

             Summary: array_distinct function does not work correctly with columns containing array of array
                 Key: SPARK-27134
                 URL: https://issues.apache.org/jira/browse/SPARK-27134
             Project: Spark
          Issue Type: Bug
          Components: SQL
    Affects Versions: 2.4.0
         Environment: Spark 2.4, scala 2.11.11
            Reporter: Mike Trenaman


The array_distinct function introduced in spark 2.4 is producing strange results when used on an array column which contains a nested array. The resulting output can still contain duplicate values, and furthermore, previously distinct values may be removed.

This is easily repeatable, e.g. with this code:

val df = Seq(
 Seq(Seq(1, 2), Seq(1, 2), Seq(1, 2), Seq(3, 4), Seq(4, 5))
 ).toDF("Number_Combinations")

val dfWithDistinct = df.withColumn("distinct_combinations",
 array_distinct(col("Number_Combinations")))

 

The initial 'df' DataFrame contains one row, where column 'Number_Combinations' contains the following values:

[[1, 2], [1, 2], [1, 2], [3, 4], [4, 5]]

 

The array_distinct function run on this column produces a new column containing the following values:

[[1, 2], [1, 2], [1, 2]]

 

As you can see, this contains three occurrences of the same value (1, 2), and furthermore, the distinct values (3, 4), (4, 5) have been removed.

 

 



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