Github user cloud-fan commented on a diff in the pull request:
https://github.com/apache/spark/pull/14444#discussion_r78928177
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/complexTypeCreator.scala
---
@@ -174,59 +174,32 @@ case class CreateMap(children: Seq[Expression])
extends Expression {
/**
* Returns a Row containing the evaluation of all children expressions.
*/
-@ExpressionDescription(
- usage = "_FUNC_(col1, col2, col3, ...) - Creates a struct with the given
field values.")
-case class CreateStruct(children: Seq[Expression]) extends Expression {
-
- override def foldable: Boolean = children.forall(_.foldable)
-
- override lazy val dataType: StructType = {
- val fields = children.zipWithIndex.map { case (child, idx) =>
- child match {
- case ne: NamedExpression =>
- StructField(ne.name, ne.dataType, ne.nullable, ne.metadata)
- case _ =>
- StructField(s"col${idx + 1}", child.dataType, child.nullable,
Metadata.empty)
+object CreateStruct extends (Seq[Expression] => CreateNamedStruct) {
+ def apply(children: Seq[Expression]) : CreateNamedStruct = {
+ val namedStructArgs = {
+ val attNames = for {
+ (child, idx) <- children.zipWithIndex
+ } yield {
+ child match {
+ case ne: NamedExpression => ne.name
+ case _ => s"col${idx + 1}"
--- End diff --
I'd argue that we break it already. In the previous `CreateStruct`, the
field name is inherited from **resolved** `NamedExpression`, but now we get it
from the `NamedExpression` that may not be resolved. This can bring
inconsistency, e.g. after resolve `UnresolvedAttribute` to `AttriuteReference`,
the name may change.
If you agree that default column name is not a backwards compatibility
issue, why do you treat default struct field name a backwards compatibility
issue?
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