address yhuai's comments

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Analyzer.scala

@@ -75,23 +75,19 @@ class Analyzer(
    * Substitute child plan with cte definitions
    */
   object CTESubstitution extends Rule[LogicalPlan] {
+    // TODO allow subquery to define CTE
     def apply(plan: LogicalPlan): LogicalPlan = plan match {
       case With(child, relations) => substituteCTE(child, relations)
       case other => other
     }
 
     def substituteCTE(plan: LogicalPlan, cteRelations: Map[String, LogicalPlan]): LogicalPlan = {
       plan transform {
-        case i @ InsertIntoTable(u: UnresolvedRelation, _, _, _, _) =>
-          // In hive, if there is same table name in database and CTE definition,
-          // hive will use the table in database, not the CTE one.
-          // Taking into account the reasonableness and the implementation complexity,
-          // here use the CTE definition first, check table name only and ignore database name
-          val substituted = cteRelations.get(u.tableIdentifier.last).map { relation =>
-            val withAlias = u.alias.map(Subquery(_, relation))
-            withAlias.getOrElse(relation)
-          }
-          i.copy(table = substituted.getOrElse(u))
+        // In hive, if there is same table name in database and CTE definition,
+        // hive will use the table in database, not the CTE one.
+        // Taking into account the reasonableness and the implementation complexity,
+        // here use the CTE definition first, check table name only and ignore database name
+        // see https://github.com/apache/spark/pull/4929#discussion_r27186638 for more info
         case u : UnresolvedRelation =>
           val substituted = cteRelations.get(u.tableIdentifier.last).map { relation =>
             val withAlias = u.alias.map(Subquery(_, relation))