Github user jaceklaskowski commented on a diff in the pull request:
https://github.com/apache/spark/pull/14444#discussion_r73336967
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Analyzer.scala
---
@@ -2065,18 +2065,28 @@ object EliminateUnions extends Rule[LogicalPlan] {
*/
object CleanupAliases extends Rule[LogicalPlan] {
private def trimAliases(e: Expression): Expression = {
- var stop = false
e.transformDown {
- // CreateStruct is a special case, we need to retain its top level
Aliases as they decide the
- // name of StructField. We also need to stop transform down this
expression, or the Aliases
- // under CreateStruct will be mistakenly trimmed.
- case c: CreateStruct if !stop =>
- stop = true
- c.copy(children = c.children.map(trimNonTopLevelAliases))
- case c: CreateStructUnsafe if !stop =>
- stop = true
- c.copy(children = c.children.map(trimNonTopLevelAliases))
- case Alias(child, _) if !stop => child
+ /**
+ * [[CreateStruct]] is a special case as it uses its top level
Aliases to decide the
+ * name of StructField.
+ * we tackle this by replacing [[CreateStruct]] with
[[CreateNamedStruct]]
+ * which encodes the field names as child literals.
+ */
+ case c @ CreateStruct(children) =>
+ CreateNamedStruct( mkNamedStructArgs(c.dataType, children))
+ case c @ CreateStructUnsafe(children) =>
+ CreateNamedStructUnsafe( mkNamedStructArgs(c.dataType, children))
+ case Alias(child, _) => child
+ }
+ }
+
+ private def mkNamedStructArgs( structType : StructType,
attributeExpressions: Seq[Expression]) = {
+ for {
+ (name, expression) <- structType.fieldNames.zip(attributeExpressions)
+ nameLiteral = Literal(name)
+ newChild <- Seq(nameLiteral, expression)
+ } yield{
+ newChild
--- End diff --
Do we really need `{` around `newChild`?
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