[GitHub] [spark] maropu commented on a change in pull request #31843: [SPARK-34749][SQL] Simplify CreateNamedStruct

[GitBox <gi...@apache.org>]

maropu commented on a change in pull request #31843:
URL: https://github.com/apache/spark/pull/31843#discussion_r595948276



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File path: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/complexTypeCreator.scala
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@@ -339,6 +339,14 @@ object CreateStruct {
    */
   def apply(children: Seq[Expression]): CreateNamedStruct = {
     CreateNamedStruct(children.zipWithIndex.flatMap {
+      // For multi-part column name like `struct(a.b.c)`, it may be resolved into:
+      //   1. Attribute if `a.b.c` is simply a qualified column name.
+      //   2. GetStructField if `a.b` refers to a struct-type column.
+      //   3. GetArrayStructFields if `a.b` refers to a array-of-struct-type column.
+      //   4. GetMapValue if `a.b` refers to a map-type column.
+      // We should always use the last part of the column name (`c` in the above example) as the
+      // alias name inside CreateNamedStruct.
+      case (u: UnresolvedAttribute, _) => Seq(Literal(u.nameParts.last), u)

Review comment:
       Ah, I see. This change makes `ResolveCreateNamedStruct` simpler. The fix seems smart.




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