Github user cloud-fan commented on a diff in the pull request:
https://github.com/apache/spark/pull/10577#discussion_r49790507
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/HiveTypeCoercion.scala
---
@@ -200,41 +203,70 @@ object HiveTypeCoercion {
*/
object WidenSetOperationTypes extends Rule[LogicalPlan] {
- private[this] def widenOutputTypes(
- planName: String,
- left: LogicalPlan,
- right: LogicalPlan): (LogicalPlan, LogicalPlan) = {
- require(left.output.length == right.output.length)
+ private def widenOutputTypes(children: Seq[LogicalPlan]):
Seq[LogicalPlan] = {
+ require(children.forall(_.output.length ==
children.head.output.length))
- val castedTypes = left.output.zip(right.output).map {
- case (lhs, rhs) if lhs.dataType != rhs.dataType =>
- findWiderTypeForTwo(lhs.dataType, rhs.dataType)
- case other => None
- }
+ // Get a sequence of data types, each of which is the widest type of
this specific attribute
+ // in all the children
+ val castedTypes: Seq[DataType] =
+ getCastedTypes(children, attrIndex = 0, mutable.Queue[DataType]())
- def castOutput(plan: LogicalPlan): LogicalPlan = {
- val casted = plan.output.zip(castedTypes).map {
- case (e, Some(dt)) if e.dataType != dt =>
- Alias(Cast(e, dt), e.name)()
- case (e, _) => e
- }
- Project(casted, plan)
+ // Add extra Project for type promotion if necessary
+ if (castedTypes.isEmpty) children else children.map(castOutput(_,
castedTypes))
+ }
+
+ // Add Project if the data types do not match
+ private def castOutput(
+ plan: LogicalPlan,
+ castedTypes: Seq[DataType]): LogicalPlan = {
+ val casted = plan.output.zip(castedTypes).map {
+ case (e, dt) if e.dataType != dt =>
+ Alias(Cast(e, dt), e.name)()
+ case (e, _) => e
}
+ if (casted.exists(_.isInstanceOf[Alias])) Project(casted, plan) else
plan
+ }
- if (castedTypes.exists(_.isDefined)) {
- (castOutput(left), castOutput(right))
- } else {
- (left, right)
+ // Get the widest type for each attribute in all the children
+ @tailrec private def getCastedTypes(
+ children: Seq[LogicalPlan],
+ attrIndex: Int,
+ castedTypes: mutable.Queue[DataType]): Seq[DataType] = {
+ // Return the result after the widen data types have been found for
all the children
+ if (attrIndex >= children.head.output.length) return
castedTypes.toSeq
+
+ // For the attrIndex-th attribute, find the widest type
+ val initialType = Option(children.head.output(attrIndex).dataType)
+ children.foldLeft(initialType) { (currentOutputDataTypes, child) =>
--- End diff --
is this just `findWiderCommonType(child.output.map(_.dataType))`?
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