cloud-fan commented on code in PR #45383:
URL: https://github.com/apache/spark/pull/45383#discussion_r1530367223
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sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/TypeCoercion.scala:
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@@ -764,6 +773,184 @@ abstract class TypeCoercionBase {
}
}
+ object CollationTypeCasts extends TypeCoercionRule {
+ override val transform: PartialFunction[Expression, Expression] = {
+ case e if !e.childrenResolved => e
+
+ case checkCastWithIndeterminate: Concat
+ if shouldCast(checkCastWithIndeterminate.children) =>
+ val newChildren =
+ collateToSingleType(checkCastWithIndeterminate.children,
failOnIndeterminate = false)
+ checkCastWithIndeterminate.withNewChildren(newChildren)
+
+ case checkCastWithoutIndeterminate@(_: BinaryExpression | _: In | _:
SortOrder)
+ if shouldCast(checkCastWithoutIndeterminate.children) =>
+ val newChildren =
collateToSingleType(checkCastWithoutIndeterminate.children)
+ checkCastWithoutIndeterminate.withNewChildren(newChildren)
+
+ case checkIndeterminate@(_: BinaryExpression | _: In | _: SortOrder)
+ if hasIndeterminate(checkIndeterminate.children
+ .filter(e => hasStringType(e.dataType))
+ .map(e => extractStringType(e.dataType))) =>
+ throw QueryCompilationErrors.indeterminateCollationError()
+
+ case checkImplicitCastInputTypes: ImplicitCastInputTypes
+ if checkImplicitCastInputTypes.children.exists(e =>
hasStringType(e.dataType))
+ && checkImplicitCastInputTypes.inputTypes.nonEmpty =>
+ val collationId: Int =
+ getOutputCollation(checkImplicitCastInputTypes
+ .children.filter { e => hasStringType(e.dataType) })
+ val children: Seq[Expression] = checkImplicitCastInputTypes
+ .children.zip(checkImplicitCastInputTypes.inputTypes).map {
+ case (e, st) if hasStringType(st) =>
+ castStringType(e, collationId, Some(st)).getOrElse(e)
+ case (e, TypeCollection(types)) if types.exists(hasStringType) =>
+ types.flatMap{ dt =>
+ if (hasStringType(dt)) {
+ castStringType(e, collationId, Some(dt))
+ } else {
+ implicitCast(e, dt)
+ }
+ }.headOption.getOrElse(e)
+ case (in, expected) => implicitCast(in, expected).getOrElse(in)
+ }
+ checkImplicitCastInputTypes.withNewChildren(children)
+
+ case checkExpectsInputType: ExpectsInputTypes
Review Comment:
Unfortunately, we do not have a trait to indicate the inputs of an
expression should all be the same data type. We have various type coercion
rules to do it for various expressions: `InConversion`, `ConcatCoercion`,
`IfCoercion`, etc.
This is probably not a big problem, as not many functions support more than
one string input and we can add a new rule to merge string collations.
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