viirya commented on a change in pull request #23726: [SPARK-26812][SQL] Report
correct nullability for complex datatypes in Union
URL: https://github.com/apache/spark/pull/23726#discussion_r253761672
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File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/logical/basicLogicalOperators.scala
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@@ -230,9 +231,19 @@ case class Union(children: Seq[LogicalPlan]) extends
LogicalPlan {
}
// updating nullability to make all the children consistent
- override def output: Seq[Attribute] =
- children.map(_.output).transpose.map(attrs =>
- attrs.head.withNullability(attrs.exists(_.nullable)))
+ override def output: Seq[Attribute] = {
+ children.map(_.output).transpose.map { attrs =>
+ val firstAttr = attrs.head
+ val outAttr = try {
+ firstAttr.withDataType(attrs.map(_.dataType).reduce(StructType.merge))
Review comment:
Adding `withDataType` to `Attribute` seems overkill to me. It is also weird
to change an attribute's data type. Should we just create an attribute here
manually?
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