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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