Mike Trenaman created SPARK-27134:
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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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