Github user ueshin commented on a diff in the pull request:
https://github.com/apache/spark/pull/22017#discussion_r209820348
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/higherOrderFunctions.scala
---
@@ -496,3 +496,195 @@ case class ArrayAggregate(
override def prettyName: String = "aggregate"
}
+
+/**
+ * Merges two given maps into a single map by applying function to the
pair of values with
+ * the same key.
+ */
+@ExpressionDescription(
+ usage =
+ """
+ _FUNC_(map1, map2, function) - Merges two given maps into a single
map by applying
+ function to the pair of values with the same key. For keys only
presented in one map,
+ NULL will be passed as the value for the missing key. If an input
map contains duplicated
+ keys, only the first entry of the duplicated key is passed into the
lambda function.
+ """,
+ examples = """
+ Examples:
+ > SELECT _FUNC_(map(1, 'a', 2, 'b'), map(1, 'x', 2, 'y'), (k, v1,
v2) -> concat(v1, v2));
+ {1:"ax",2:"by"}
+ """,
+ since = "2.4.0")
+case class MapZipWith(left: Expression, right: Expression, function:
Expression)
+ extends HigherOrderFunction with CodegenFallback {
+
+ @transient lazy val functionForEval: Expression = functionsForEval.head
+
+ @transient lazy val MapType(leftKeyType, leftValueType,
leftValueContainsNull) = left.dataType
+
+ @transient lazy val MapType(rightKeyType, rightValueType,
rightValueContainsNull) = right.dataType
+
+ @transient lazy val keyType =
+ TypeCoercion.findCommonTypeDifferentOnlyInNullFlags(leftKeyType,
rightKeyType).get
+
+ @transient lazy val ordering = TypeUtils.getInterpretedOrdering(keyType)
+
+ override def arguments: Seq[Expression] = left :: right :: Nil
+
+ override def argumentTypes: Seq[AbstractDataType] = MapType :: MapType
:: Nil
+
+ override def functions: Seq[Expression] = function :: Nil
+
+ override def functionTypes: Seq[AbstractDataType] = AnyDataType :: Nil
+
+ override def nullable: Boolean = left.nullable || right.nullable
+
+ override def dataType: DataType = MapType(keyType, function.dataType,
function.nullable)
+
+ override def bind(f: (Expression, Seq[(DataType, Boolean)]) =>
LambdaFunction): MapZipWith = {
+ val arguments = Seq((keyType, false), (leftValueType, true),
(rightValueType, true))
+ copy(function = f(function, arguments))
+ }
+
+ override def checkArgumentDataTypes(): TypeCheckResult = {
+ super.checkArgumentDataTypes() match {
+ case TypeCheckResult.TypeCheckSuccess =>
+ if (leftKeyType.sameType(rightKeyType)) {
+ TypeUtils.checkForOrderingExpr(leftKeyType, s"function
$prettyName")
+ } else {
+ TypeCheckResult.TypeCheckFailure(s"The input to function
$prettyName should have " +
+ s"been two ${MapType.simpleString}s with compatible key types,
but the key types are " +
+ s"[${leftKeyType.catalogString},
${rightKeyType.catalogString}].")
+ }
+ case failure => failure
+ }
+ }
+
+ // Nothing to check since the data type of the lambda function can be
anything.
+ override def checkInputDataTypes(): TypeCheckResult =
TypeCheckResult.TypeCheckSuccess
--- End diff --
I'd call `checkArgumentDataTypes()` here again.
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