Github user gatorsmile commented on a diff in the pull request:
https://github.com/apache/spark/pull/10577#discussion_r49186437
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/HiveTypeCoercion.scala
---
@@ -200,41 +200,62 @@ object HiveTypeCoercion {
*/
object WidenSetOperationTypes extends Rule[LogicalPlan] {
- private[this] def widenOutputTypes(
+ private def widenOutputTypes(
planName: String,
- left: LogicalPlan,
- right: LogicalPlan): (LogicalPlan, LogicalPlan) = {
- require(left.output.length == right.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
+ children: Seq[LogicalPlan]): Seq[LogicalPlan] = {
+ require(children.forall(_.output.length ==
children.head.output.length))
+
+ // Get a sequence of data types, each of which is the widest type of
this specific attribute
+ // in all the children
+ val castedTypes: Seq[Option[DataType]] = {
+ val initialTypeSeq = children.head.output.map(a =>
Option(a.dataType))
+ children.tail.foldLeft(initialTypeSeq) { (currentOutputDataTypes,
child) =>
+ // Find the wider type if the data type of this child do not
match with
+ // the casted data types of the already processed children
+ getCastedTypes(currentOutputDataTypes, child.output)
+ }
}
- 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
+ children.map(castOutput(_, castedTypes))
+ }
+
+ // Add Project if the data types do not match
+ private def castOutput(
+ plan: LogicalPlan,
+ castedTypes: Seq[Option[DataType]]): 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
}
+ if (casted.exists(_.isInstanceOf[Alias])) Project(casted, plan) else
plan
+ }
- if (castedTypes.exists(_.isDefined)) {
- (castOutput(left), castOutput(right))
- } else {
- (left, right)
+ private def getCastedTypes(
+ typeSeq: Seq[Option[DataType]],
+ attrSeq: Seq[Attribute]): Seq[Option[DataType]] = {
+ typeSeq.zip(attrSeq).map {
+ case (Some(dt), ar) if dt != ar.dataType =>
+ findWiderTypeForTwo(dt, ar.dataType)
+ case (Some(dt), ar) if dt == ar.dataType => Option(dt)
--- End diff --
This is required when you have more than two children. For example, the
first two children have the same type but the third has different type.
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