Github user marmbrus commented on a diff in the pull request:
https://github.com/apache/spark/pull/1266#discussion_r14543110
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/logical/basicOperators.scala
---
@@ -46,10 +46,22 @@ case class Generate(
child: LogicalPlan)
extends UnaryNode {
- protected def generatorOutput: Seq[Attribute] =
- alias
+ protected def generatorOutput: Seq[Attribute] = {
+ val output = alias
.map(a => generator.output.map(_.withQualifiers(a :: Nil)))
.getOrElse(generator.output)
+ if (join && outer) {
+ output.map {
+ case attr if !attr.resolved => attr
+ case attr if !attr.nullable =>
+ AttributeReference(
+ attr.name, attr.dataType, nullable = true)(attr.exprId,
attr.qualifiers)
+ case attr => attr
--- End diff --
This is a pretty common pattern. We already have
[`withNullability`](https://github.com/apache/spark/blob/master/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/namedExpressions.scala#L136),
which you could use in these cases if we move it up as an abstract method in
`Attribute` and add a no-op version in `UnresolvedAttribute`.
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