Github user mgaido91 commented on a diff in the pull request:
https://github.com/apache/spark/pull/21024#discussion_r180414332
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/collectionOperations.scala
---
@@ -287,3 +287,61 @@ case class ArrayContains(left: Expression, right:
Expression)
override def prettyName: String = "array_contains"
}
+
+
+/**
+ * Returns the maximum value in the array.
+ */
+@ExpressionDescription(
+usage = "_FUNC_(array) - Returns the maximum value in the array.",
+examples = """
+ Examples:
+ > SELECT _FUNC_(array(1, 20, null, 3));
+ 20
+ """, since = "2.4.0")
+case class ArrayMax(child: Expression) extends UnaryExpression with
ImplicitCastInputTypes {
+
+ override def nullable: Boolean =
+ child.nullable || child.dataType.asInstanceOf[ArrayType].containsNull
+
+ override def foldable: Boolean = child.foldable
+
+ override def inputTypes: Seq[AbstractDataType] = Seq(ArrayType)
+
+ private lazy val ordering = TypeUtils.getInterpretedOrdering(dataType)
+
+ override protected def doGenCode(ctx: CodegenContext, ev: ExprCode):
ExprCode = {
+ val childGen = child.genCode(ctx)
+ val javaType = CodeGenerator.javaType(dataType)
+ val i = ctx.freshName("i")
+ val item = ExprCode("",
+ isNull = StatementValue(s"${childGen.value}.isNullAt($i)",
"boolean"),
+ value = StatementValue(CodeGenerator.getValue(childGen.value,
dataType, i), javaType))
+ ev.copy(code =
+ s"""
+ |${childGen.code}
+ |boolean ${ev.isNull} = true;
+ |$javaType ${ev.value} = ${CodeGenerator.defaultValue(dataType)};
+ |if (!${childGen.isNull}) {
+ | for (int $i = 0; $i < ${childGen.value}.numElements(); $i ++) {
+ | ${ctx.reassignIfGreater(dataType, ev, item)}
+ | }
+ |}
+ """.stripMargin)
+ }
+
+ override protected def nullSafeEval(input: Any): Any = {
+ var max: Any = null
+ input.asInstanceOf[ArrayData].foreach(dataType, (_, item) =>
+ if (item != null && (max == null || ordering.gt(item, max))) {
+ max = item
+ }
+ )
+ max
+ }
+
+ override def dataType: DataType = child.dataType match {
+ case ArrayType(dt, _) => dt
--- End diff --
I added the check in the `checkInputDataTypes` method, thanks.
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