diff --git a/src/main/scala/catalyst/analysis/HiveTypeCoercion.scala b/src/main/scala/catalyst/analysis/HiveTypeCoercion.scala
index fced1e2df89fa..ce2f660a7c778 100644
--- a/src/main/scala/catalyst/analysis/HiveTypeCoercion.scala
+++ b/src/main/scala/catalyst/analysis/HiveTypeCoercion.scala
@@ -190,7 +190,7 @@ trait HiveTypeCoercion {
       case Sum(e) if e.dataType == StringType =>
         Sum(Cast(e, DoubleType))
       case Average(e) if e.dataType == StringType =>
-        Sum(Cast(e, DoubleType))
+        Average(Cast(e, DoubleType))
     }
   }
 
@@ -252,7 +252,6 @@ trait HiveTypeCoercion {
       case s @ Sum(e @ DecimalType()) => s // Decimal is already the biggest.
       case Sum(e @ IntegralType()) if e.dataType != LongType => Sum(Cast(e, LongType))
       case Sum(e @ FractionalType()) if e.dataType != DoubleType => Sum(Cast(e, DoubleType))
-
     }
   }
 }
diff --git a/src/main/scala/catalyst/rules/RuleExecutor.scala b/src/main/scala/catalyst/rules/RuleExecutor.scala
index 59c5f29c83f49..69cd1dae5b00a 100644
--- a/src/main/scala/catalyst/rules/RuleExecutor.scala
+++ b/src/main/scala/catalyst/rules/RuleExecutor.scala
@@ -2,8 +2,9 @@ package catalyst
 package rules
 
 import trees._
+import util._
 
-abstract class RuleExecutor[TreeType <: TreeNode[_]] {
+abstract class RuleExecutor[TreeType <: TreeNode[_]] extends Logging {
 
   /**
    * An execution strategy for rules that indicates the maximum number of executions. If the
@@ -38,7 +39,19 @@ abstract class RuleExecutor[TreeType <: TreeNode[_]] {
       // Run until fix point (or the max number of iterations as specified in the strategy.
       while (iteration < batch.strategy.maxIterations && !curPlan.fastEquals(lastPlan)) {
         lastPlan = curPlan
-        curPlan = batch.rules.foldLeft(curPlan) { case (curPlan, rule) => rule(curPlan) }
+        curPlan = batch.rules.foldLeft(curPlan) {
+          case (curPlan, rule) =>
+            val result = rule(curPlan)
+            if(!result.fastEquals(curPlan)) {
+              logger.debug(
+                s"""
+                  |=== Applying Rule ${rule.ruleName} ===
+                  |${sideBySide(curPlan.treeString, result.treeString).mkString("\n")}
+                """.stripMargin)
+            }
+
+            result
+        }
         iteration += 1
       }
     }