Github user ueshin commented on a diff in the pull request:
https://github.com/apache/spark/pull/21073#discussion_r192919160
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/collectionOperations.scala
---
@@ -308,6 +308,170 @@ case class MapEntries(child: Expression) extends
UnaryExpression with ExpectsInp
override def prettyName: String = "map_entries"
}
+/**
+ * Returns the union of all the given maps.
+ */
+@ExpressionDescription(
+usage = "_FUNC_(map, ...) - Returns the union of all the given maps",
+examples = """
+ Examples:
+ > SELECT _FUNC_(map(1, 'a', 2, 'b'), map(2, 'c', 3, 'd'));
+ [[1 -> "a"], [2 -> "c"], [3 -> "d"]
+ """, since = "2.4.0")
+case class MapConcat(children: Seq[Expression]) extends Expression {
+
+ override def checkInputDataTypes(): TypeCheckResult = {
+ // check key types and value types separately to allow
valueContainsNull to vary
+ if (children.exists(!_.dataType.isInstanceOf[MapType])) {
+ TypeCheckResult.TypeCheckFailure(
+ s"The given input of function $prettyName should all be of type
map, " +
+ "but they are " +
children.map(_.dataType.simpleString).mkString("[", ", ", "]"))
+ } else if (children.map(_.dataType.asInstanceOf[MapType].keyType)
+ .exists(_.isInstanceOf[MapType])) {
+ // map_concat needs to pick a winner when multiple maps contain the
same key. map_concat
+ // can do that only if it can detect when two keys are the same.
SPARK-9415 states "map type
+ // should not support equality, hash". As a result, map_concat does
not support a map type
+ // as a key
+ TypeCheckResult.TypeCheckFailure(
+ s"The given input maps of function $prettyName cannot have a map
type as a key")
+ } else if
(children.map(_.dataType.asInstanceOf[MapType].keyType).distinct.length > 1) {
+ TypeCheckResult.TypeCheckFailure(
+ s"The given input maps of function $prettyName should all be the
same type, " +
+ "but they are " +
children.map(_.dataType.simpleString).mkString("[", ", ", "]"))
+ } else if
(children.map(_.dataType.asInstanceOf[MapType].valueType).distinct.length > 1) {
+ TypeCheckResult.TypeCheckFailure(
+ s"The given input maps of function $prettyName should all be the
same type, " +
+ "but they are " +
children.map(_.dataType.simpleString).mkString("[", ", ", "]"))
+ } else {
+ TypeCheckResult.TypeCheckSuccess
+ }
+ }
+
+ override def dataType: MapType = {
+ MapType(
--- End diff --
How about doing `children.map(_.dataType.asInstanceOf[MapType])` first?
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