address comments.

sql/hive/src/main/scala/org/apache/spark/sql/hive/SQLBuilder.scala

@@ -208,9 +208,9 @@ class SQLBuilder(logicalPlan: LogicalPlan, sqlContext: SQLContext) extends Loggi
       throw new UnsupportedOperationException(s"unsupported plan $node")
   }
 
-  private def sameOutput(left: Seq[Attribute], right: Seq[Attribute]): Boolean =
-    left.forall(a => right.exists(_.semanticEquals(a))) &&
-      right.forall(a => left.exists(_.semanticEquals(a)))
+  private def sameOutput(output1: Seq[Attribute], output2: Seq[Attribute]): Boolean =
+    output1.size == output2.size &&
+      output1.zip(output2).forall(pair => pair._1.semanticEquals(pair._2))
 
   /**
    * Turns a bunch of string segments into a single string and separate each segment by a space.
@@ -243,40 +243,49 @@ class SQLBuilder(logicalPlan: LogicalPlan, sqlContext: SQLContext) extends Loggi
   }
 
   private def groupingSetToSQL(
-      plan: Aggregate,
+      agg: Aggregate,
       expand: Expand,
       project: Project): String = {
-    require(plan.groupingExpressions.length > 1)
+    assert(agg.groupingExpressions.length > 1)
 
     // The last column of Expand is always grouping ID
     val gid = expand.output.last
 
-    val groupByAttributes = plan.groupingExpressions.dropRight(1).map(_.asInstanceOf[Attribute])
-    val groupByExprs =
-      project.projectList.drop(project.child.output.length).map(_.asInstanceOf[Alias].child)
-    val groupByAttrMap = AttributeMap(groupByAttributes.zip(groupByExprs))
+    val numOriginalOutput = project.child.output.length
+    // Assumption: Aggregate's groupingExpressions is composed of
+    // 1) the group by attributes' aliases
+    // 2) gid, which is always the last one
+    val groupByAttributes = agg.groupingExpressions.dropRight(1).map(_.asInstanceOf[Attribute])
+    // Assumption: Project's projectList is composed of
+    // 1) the original output (Project's child.output),
+    // 2) the aliases of the original group by attributes, which could be expressions
+    val groupByExprs = project.projectList.drop(numOriginalOutput).map(_.asInstanceOf[Alias].child)
     val groupingSQL = groupByExprs.map(_.sql).mkString(", ")
 
+    // a map from the alias name to the original group by expresions/attributes
+    val groupByAttrMap = AttributeMap(groupByAttributes.zip(groupByExprs))
+
     val groupingSet = expand.projections.map { project =>
-      // Assumption: expand.projections are composed of
+      // Assumption: expand.projections is composed of
       // 1) the original output (Project's child.output),
       // 2) group by attributes(or null literal)
       // 3) gid, which is always the last one in each project in Expand
-      project.dropRight(1).collect {
+      project.drop(numOriginalOutput).dropRight(1).collect {
         case attr: Attribute if groupByAttrMap.contains(attr) => groupByAttrMap(attr)
       }
     }
     val groupingSetSQL =
       "GROUPING SETS(" +
         groupingSet.map(e => s"(${e.map(_.sql).mkString(", ")})").mkString(", ") + ")"
 
-    val aggExprs = plan.aggregateExpressions.map { case expr =>
+    val aggExprs = agg.aggregateExpressions.map { case expr =>
       expr.transformDown {
         // grouping_id() is converted to VirtualColumn.groupingIdName by Analyzer. Revert it back.
-        case ar: AttributeReference if ar eq gid => GroupingID(Nil)
-        case a @ Alias(_ @ Cast(BitwiseAnd(
+        case ar: AttributeReference if ar == gid => GroupingID(Nil)
+        case ar: AttributeReference if groupByAttrMap.contains(ar) => groupByAttrMap(ar)
+        case a @ Cast(BitwiseAnd(
             ShiftRight(ar: AttributeReference, _ @ Literal(value: Any, IntegerType)),
-            Literal(1, IntegerType)), ByteType), name) if ar == gid =>
+            Literal(1, IntegerType)), ByteType) if ar == gid =>
           // for converting an expression to its original SQL format grouping(col)
           val idx = groupByExprs.length - 1 - value.asInstanceOf[Int]
           val groupingCol = groupByExprs.lift(idx)
@@ -285,17 +294,13 @@ class SQLBuilder(logicalPlan: LogicalPlan, sqlContext: SQLContext) extends Loggi
           } else {
             throw new UnsupportedOperationException(s"unsupported operator $a")
           }
-        case a @ Alias(ar: AttributeReference, _) if groupByAttrMap.contains(ar) =>
-          groupByAttrMap(ar)
-        case ar: AttributeReference if groupByAttrMap.contains(ar) =>
-          groupByAttrMap(ar)
       }
     }
 
     build(
       "SELECT",
       aggExprs.map(_.sql).mkString(", "),
-      if (plan.child == OneRowRelation) "" else "FROM",
+      if (agg.child == OneRowRelation) "" else "FROM",
       toSQL(project.child),
       "GROUP BY",
       groupingSQL,