ueshin commented on a change in pull request #25728: [SPARK-29020][WIP][SQL]
Improving array_sort behaviour
URL: https://github.com/apache/spark/pull/25728#discussion_r336981686
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/higherOrderFunctions.scala
##########
@@ -285,6 +287,112 @@ case class ArrayTransform(
override def prettyName: String = "transform"
}
+/**
+ * Sorts elements in an array using a comparator function.
+ */
+@ExpressionDescription(
+ usage = "_FUNC_(expr, func) - Sorts the input array in ascending order. The
elements of the " +
+ "input array must be orderable. Null elements will be placed at the end of
the returned " +
+ "array. Since 3.0.0 also sorts and returns the array based on the given " +
+ "comparator function. The comparator will take two nullable arguments " +
+ "representing two nullable elements of the array." +
+ "It returns -1, 0, or 1 as the first nullable element is less than, equal
to, or greater " +
+ "than the second nullable element. If the comparator function returns
other " +
+ "values (including NULL), the query will fail and raise an error.",
+ examples = """
+ Examples:
+ > SELECT _FUNC_(array(5, 6, 1), (x, y) -> f(x, y));
+ [1,5,6]
+ > SELECT _FUNC_(array('bc', 'ab', 'dc'), (x, y) -> f(x, y));
+ ["dc", "bc", "ab"]
+ > SELECT _FUNC_(array('b', 'd', null, 'c', 'a'));
+ | ["d", "c", "b", "a", null]
+ """,
+ since = "2.4.0")
+case class ArraySort(
+ argument: Expression,
+ function: Expression)
+ extends ArrayBasedSimpleHigherOrderFunction with ArraySortLike with
CodegenFallback {
+
+ def this(argument: Expression) = this(argument, Literal(true))
+
+ @transient lazy val argumentsType: DataType =
+ argument.dataType.asInstanceOf[ArrayType].elementType
+
+ override protected def arrayExpression: Expression = argument
+
+ override protected def nullOrder: NullOrder = NullOrder.Greatest
+
+ override def dataType: ArrayType = argument.dataType.asInstanceOf[ArrayType]
+
+ override def checkInputDataTypes(): TypeCheckResult = {
+
+ if (function.dataType == BooleanType) {
+ argument.dataType match {
+ case ArrayType(dt, _) if RowOrdering.isOrderable(dt) =>
+ TypeCheckResult.TypeCheckSuccess
+ case ArrayType(dt, _) =>
+ val dtSimple = dt.catalogString
+ TypeCheckResult.TypeCheckFailure(
+ s"$prettyName does not support sorting array of type $dtSimple
which is not orderable")
+ case _ =>
+ TypeCheckResult.TypeCheckFailure(s"$prettyName only supports array
input.")
+ }
+ } else {
+ checkArgumentDataTypes() match {
+ case TypeCheckResult.TypeCheckSuccess =>
+ val LambdaFunction(_, arguments, _) = function
+ if (arguments.size == 2 && function.dataType == IntegerType) {
+ TypeCheckResult.TypeCheckSuccess
+ } else {
+ TypeCheckResult.TypeCheckFailure("Return type of the given
function has to be " +
+ "IntegerType")
+ }
+
+ case failure => failure
+ }
+ }
+ }
+
+ override def bind(f: (Expression, Seq[(DataType, Boolean)]) =>
LambdaFunction): ArraySort = {
+ val ArrayType(elementType, containsNull) = argument.dataType
+ copy(function =
+ f(function, (elementType, containsNull) :: (elementType,
containsNull) :: Nil))
+ }
+
+ @transient lazy val (firstParam, secondParam) = {
+ val LambdaFunction(_, (firstParam: NamedLambdaVariable) +: tail, _) =
function
+ val secondParam = tail.head.asInstanceOf[NamedLambdaVariable]
+ (firstParam, secondParam)
+ }
+
+ def comparator(inputRow: InternalRow): Comparator[Any] = {
+ val f = functionForEval
+ (o1: Any, o2: Any) => {
+ if (o1 == null && o2 == null) {
Review comment:
I think the comparator function should be responsible the null order as
well. (the same comment as
https://github.com/apache/spark/pull/25728#discussion_r325822500)
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