Github user yijieshen commented on a diff in the pull request:
https://github.com/apache/spark/pull/6938#discussion_r34000276
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/math.scala
---
@@ -600,3 +604,146 @@ case class Logarithm(left: Expression, right:
Expression)
"""
}
}
+
+case class Round(child: Expression, scale: Expression) extends Expression
with ExpectsInputTypes {
+
+ def this(child: Expression) = {
+ this(child, Literal(0))
+ }
+
+ override def children: Seq[Expression] = Seq(child, scale)
+
+ override def nullable: Boolean = true
+
+ override def foldable: Boolean = child.foldable
+
+ override lazy val dataType: DataType = child.dataType match {
+ case DecimalType.Fixed(p, s) => DecimalType(p, _scale)
+ case t => t
+ }
+
+ override def inputTypes: Seq[AbstractDataType] = Seq(
+ // rely on precedence to implicit cast String into Double
+ TypeCollection(DecimalType, DoubleType, FloatType, LongType,
IntegerType, ShortType, ByteType),
+ TypeCollection(LongType, IntegerType, ShortType, ByteType))
+
+ override def checkInputDataTypes(): TypeCheckResult = {
+ child.dataType match {
+ case _: NumericType => // satisfy requirement
+ case dt =>
+ return TypeCheckFailure(s"Only numeric type is allowed for ROUND
function, got $dt")
+ }
+ scale match {
+ case Literal(value, LongType) =>
+ if (value.asInstanceOf[Long] < Int.MinValue ||
value.asInstanceOf[Long] > Int.MaxValue) {
+ return TypeCheckFailure("ROUND scale argument out of allowed
range")
+ }
+ case _ =>
+ if (scale.dataType.isInstanceOf[IntegralType] && scale.foldable) {
+ // TODO: How to check out of range for foldable LongType
Expression
+ // satisfy requirement
+ } else {
+ return TypeCheckFailure("Only foldable Integral Expression " +
+ s"is allowed for ROUND scale arguments, got ${child.dataType}")
--- End diff --
Yes, you are right, I was hesitate to do `eval` in checkInputDataTypes,
therefore, find it hard to check out of range for LongType foldable
expressions, and leave it in comment for some guidance. :)
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