viirya commented on a change in pull request #24073: [SPARK-27134][SQL]
array_distinct function does not work correctly with columns containing array
of array
URL: https://github.com/apache/spark/pull/24073#discussion_r265064221
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/collectionOperations.scala
##########
@@ -3112,29 +3112,30 @@ case class ArrayDistinct(child: Expression)
(data: Array[AnyRef]) => new
GenericArrayData(data.distinct.asInstanceOf[Array[Any]])
} else {
(data: Array[AnyRef]) => {
- var foundNullElement = false
- var pos = 0
+ val arrayBuffer = new scala.collection.mutable.ArrayBuffer[Any]
+ var alreadyStoredNull = false
+ var found = false
for (i <- 0 until data.length) {
- if (data(i) == null) {
- if (!foundNullElement) {
- foundNullElement = true
- pos = pos + 1
+ if (data(i) != null) {
+ found = false
+ var j = 0;
+ while (!found && j < arrayBuffer.size) {
+ val va = arrayBuffer(j)
+ found = (va != null) && ordering.equiv(va, data(i))
+ j += 1
}
- } else {
- var j = 0
- var done = false
- while (j <= i && !done) {
- if (data(j) != null && ordering.equiv(data(j), data(i))) {
- done = true
- }
- j = j + 1
+ if (!found) {
+ arrayBuffer += data(i)
}
- if (i == j - 1) {
- pos = pos + 1
+ } else {
+ // De-duplicate the null values.
+ if (!alreadyStoredNull) {
+ arrayBuffer += data(i)
+ alreadyStoredNull = true
}
}
}
- new GenericArrayData(data.slice(0, pos))
Review comment:
Looks like original implementation assumes the duplicate items are placed at
the end of `data`? I think it not only affects array of array, but also other
element type like `BinaryType`.
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