improve

Author: gengliangwang

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/logical/QueryPlanConstraints.scala

@@ -97,12 +97,15 @@ trait QueryPlanConstraints { self: LogicalPlan =>
   // Collect aliases from expressions of the whole tree rooted by the current QueryPlan node, so
   // we may avoid producing recursive constraints.
   private lazy val aliasMap: AttributeMap[Expression] = {
-    val aliases = expressions.collect {
+    val childrenAliases = children.flatMap { child =>
+      val childOutputSet = child.outputSet
+      child.asInstanceOf[QueryPlanConstraints].aliasMap.filter {
+        case (_, c) => c.references.nonEmpty && c.references.subsetOf(childOutputSet)
+      }
+    }
+    AttributeMap(expressions.collect {
       case a: Alias if !a.child.isInstanceOf[Literal] => (a.toAttribute, a.child)
-    } ++ children.flatMap(_.asInstanceOf[QueryPlanConstraints].aliasMap)
-    AttributeMap(aliases.filter {
-      case (_, child) => child.references.nonEmpty && child.references.subsetOf(outputSet)
-    })
+    } ++ childrenAliases)
   }
 
     // Note: the explicit cast is necessary, since Scala compiler fails to infer the type.