Github user gatorsmile commented on a diff in the pull request:
https://github.com/apache/spark/pull/10577#discussion_r50175266
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/HiveTypeCoercion.scala
---
@@ -219,34 +222,62 @@ object HiveTypeCoercion {
def apply(plan: LogicalPlan): LogicalPlan = plan resolveOperators {
case p if p.analyzed => p
- case s @ SetOperation(left, right) if s.childrenResolved
- && left.output.length == right.output.length && !s.resolved =>
+ case s @ SetOperation(left, right) if s.childrenResolved &&
+ left.output.length == right.output.length && !s.resolved =>
+ val newChildren: Seq[LogicalPlan] =
buildNewChildrenWithWiderTypes(left :: right :: Nil)
+ assert(newChildren.length == 2)
+ s.makeCopy(Array(newChildren.head, newChildren.last))
- // Tracks the list of data types to widen.
- // Some(dataType) means the right-hand side and the left-hand side
have different types,
- // and there is a target type to widen both sides to.
- val targetTypes: Seq[Option[DataType]] =
left.output.zip(right.output).map {
- case (lhs, rhs) if lhs.dataType != rhs.dataType =>
- findWiderTypeForTwo(lhs.dataType, rhs.dataType)
- case other => None
- }
+ case s: Union if s.childrenResolved &&
+ s.children.forall(_.output.length ==
s.children.head.output.length) && !s.resolved =>
+ val newChildren: Seq[LogicalPlan] =
buildNewChildrenWithWiderTypes(s.children)
+ s.makeCopy(Array(newChildren))
+ }
- if (targetTypes.exists(_.isDefined)) {
- // There is at least one column to widen.
- s.makeCopy(Array(widenTypes(left, targetTypes),
widenTypes(right, targetTypes)))
- } else {
- // If we cannot find any column to widen, then just return the
original set.
- s
- }
+ /** Build new children with the widest types for each attribute among
all the children */
+ private def buildNewChildrenWithWiderTypes(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 targetTypes: Seq[DataType] =
+ getWidestTypes(children, attrIndex = 0, mutable.Queue[DataType]())
+
+ if (targetTypes.nonEmpty) {
+ // Add an extra Project if the targetTypes are different from the
original types.
+ children.map(widenTypes(_, targetTypes))
+ } else {
+ // Unable to find a target type to widen, then just return the
original set.
+ children
+ }
+ }
+
+ /** Get the widest type for each attribute in all the children */
+ @tailrec private def getWidestTypes(
+ 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
+ findWiderCommonType(children.map(_.output(attrIndex).dataType))
match {
+ // If unable to find an appropriate widen type for this column,
return an empty Seq
+ case None => Seq.empty[DataType]
+ // Otherwise, record the result in the queue and find the type for
the next column
+ case Some(widenType) =>
+ castedTypes.enqueue(widenType)
+ getWidestTypes(children, attrIndex + 1, castedTypes)
+ }
}
/** Given a plan, add an extra project on top to widen some columns'
data types. */
- private def widenTypes(plan: LogicalPlan, targetTypes:
Seq[Option[DataType]]): LogicalPlan = {
+ private def widenTypes(plan: LogicalPlan, targetTypes: Seq[DataType]):
LogicalPlan = {
val casted = plan.output.zip(targetTypes).map {
- case (e, Some(dt)) if e.dataType != dt => Alias(Cast(e, dt),
e.name)()
+ case (e, dt) if e.dataType != dt => Alias(Cast(e, dt), e.name)()
case (e, _) => e
}
- Project(casted, plan)
+ if (casted.exists(_.isInstanceOf[Alias])) Project(casted, plan) else
plan
--- End diff --
Sure, let me remove it. : )
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