Github user rxin commented on a diff in the pull request:
https://github.com/apache/spark/pull/7348#discussion_r34648784
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/HiveTypeCoercion.scala
---
@@ -672,20 +659,44 @@ object HiveTypeCoercion {
}
/**
- * Casts types according to the expected input types for Expressions
that have the trait
- * [[ExpectsInputTypes]].
+ * Casts types according to the expected input types for [[Expression]]s.
*/
object ImplicitTypeCasts extends Rule[LogicalPlan] {
def apply(plan: LogicalPlan): LogicalPlan = plan
transformAllExpressions {
// Skip nodes who's children have not been resolved yet.
case e if !e.childrenResolved => e
- case e: ExpectsInputTypes if (e.inputTypes.nonEmpty) =>
+ case b @ BinaryOperator(left, right) if left.dataType !=
right.dataType =>
+ findTightestCommonTypeOfTwo(left.dataType, right.dataType).map {
commonType =>
+ if (b.inputType.acceptsType(commonType)) {
+ // If the expression accepts the tighest common type, cast to
that.
+ val newLeft = if (left.dataType == commonType) left else
Cast(left, commonType)
+ val newRight = if (right.dataType == commonType) right else
Cast(right, commonType)
+ b.makeCopy(Array(newLeft, newRight))
+ } else {
+ // Otherwise, don't do anything with the expression.
+ b
+ }
+ }.getOrElse(b) // If there is no applicable conversion, leave
expression unchanged.
+
+ case e: ImplicitCastInputTypes if e.inputTypes.nonEmpty =>
val children: Seq[Expression] = e.children.zip(e.inputTypes).map {
case (in, expected) =>
// If we cannot do the implicit cast, just use the original
input.
implicitCast(in, expected).getOrElse(in)
}
e.withNewChildren(children)
+
+ case e: ExpectsInputTypes if e.inputTypes.nonEmpty =>
+ // Convert NullType into some specific target type for
ExpectsInputTypes that don't do
+ // general implicit casting.
+ val children: Seq[Expression] = e.children.zip(e.inputTypes).map {
case (in, expected) =>
+ if (in.dataType == NullType && !expected.acceptsType(NullType)) {
+ Cast(in, expected.defaultConcreteType)
+ } else {
--- End diff --
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