Github user chenghao-intel commented on a diff in the pull request:
https://github.com/apache/spark/pull/482#discussion_r12265587
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/dsl/package.scala ---
@@ -114,37 +114,37 @@ package object dsl {
def attr = analysis.UnresolvedAttribute(s)
/** Creates a new AttributeReference of type boolean */
- def boolean = AttributeReference(s, BooleanType, nullable = false)()
--- End diff --
I think "def boolean" / "def string" should return an Attribute with
nullability = true, that does not harm for the correctness, otherwise, it may
bring a wrong hint for the optimization of rule NullPropagation.
For example:
val row = new GenericRow(Array[Any]("a", null))
val c1 = 'a.string.at(0)
val c2 = 'b.string.at(1) // nullable should be true, otherwise does't
reflect the real situation.
assert(evaluate(IsNull(c2), row) == true)
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