From 2645d4fd0acca695be02e332e7f3a69b33f7f2a1 Mon Sep 17 00:00:00 2001
From: Cheng Hao <hao.cheng@intel.com>
Date: Mon, 28 Apr 2014 10:45:26 +0800
Subject: [PATCH 01/12] Constant Folding(null propagation)

---
 .../sql/catalyst/expressions/predicates.scala |  3 +-
 .../sql/catalyst/optimizer/Optimizer.scala    | 48 +++++++++++++++++++
 2 files changed, 49 insertions(+), 2 deletions(-)

diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/predicates.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/predicates.scala
index 82c7af684459f..6ee479939d25c 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/predicates.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/predicates.scala
@@ -65,8 +65,7 @@ abstract class BinaryPredicate extends BinaryExpression with Predicate {
   def nullable = left.nullable || right.nullable
 }
 
-case class Not(child: Expression) extends Predicate with trees.UnaryNode[Expression] {
-  def references = child.references
+case class Not(child: Expression) extends UnaryExpression with Predicate {
   override def foldable = child.foldable
   def nullable = child.nullable
   override def toString = s"NOT $child"
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
index c0a09a16ac98d..e11155539fd75 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
@@ -94,11 +94,59 @@ object ConstantFolding extends Rule[LogicalPlan] {
     case q: LogicalPlan => q transformExpressionsDown {
       // Skip redundant folding of literals.
       case l: Literal => l
+      case e @ If(Literal(v, _), trueValue, falseValue) => if(v == true) trueValue else falseValue
+      case e @ In(Literal(v, _), list) if(list.exists(c => c match {
+          case Literal(candidate, _) if(candidate == v) => true
+          case _ => false
+        })) => Literal(true, BooleanType)
       case e if e.foldable => Literal(e.eval(null), e.dataType)
     }
   }
 }
 
+/**
+ * The expression may be constant value, due to one or more of its children expressions is null or 
+ * not null constantly, replaces [[catalyst.expressions.Expression Expressions]] with equivalent 
+ * [[catalyst.expressions.Literal Literal]] values if possible caused by that. 
+ */
+object NullPropagation extends Rule[LogicalPlan] {
+  def apply(plan: LogicalPlan): LogicalPlan = plan transform {
+    case q: LogicalPlan => q transformExpressionsUp {
+      case l: Literal => l
+      case e @ IsNull(Literal(null, _)) => Literal(true, BooleanType)
+      case e @ IsNull(Literal(_, _)) => Literal(false, BooleanType)
+      case e @ IsNull(c @ Rand) => Literal(false, BooleanType)
+      case e @ IsNotNull(Literal(null, _)) => Literal(false, BooleanType)
+      case e @ IsNotNull(Literal(_, _)) => Literal(true, BooleanType)
+      case e @ IsNotNull(c @ Rand) => Literal(true, BooleanType)
+      case e @ GetItem(Literal(null, _), _) => Literal(null, e.dataType)
+      case e @ GetItem(_, Literal(null, _)) => Literal(null, e.dataType)
+      case e @ GetField(Literal(null, _), _) => Literal(null, e.dataType)
+      case e @ Coalesce(children) => {
+        val newChildren = children.filter(c => c match {
+          case Literal(null, _) => false
+          case _ => true
+        })
+        if(newChildren.length == null) {
+          Literal(null, e.dataType)
+        } else if(newChildren.length == children.length){
+          e
+        } else {
+          Coalesce(newChildren)
+        }
+      }
+      // TODO put exceptional cases(Unary & Binary Expression) before here.
+      case e: UnaryExpression => e.child match {
+        case Literal(null, _) => Literal(null, e.dataType)
+      }
+      case e: BinaryExpression => e.children match {
+        case Literal(null, _) :: right :: Nil => Literal(null, e.dataType)
+        case left :: Literal(null, _) :: Nil => Literal(null, e.dataType)
+      }
+    }
+  }
+}
+
 /**
  * Simplifies boolean expressions where the answer can be determined without evaluating both sides.
  * Note that this rule can eliminate expressions that might otherwise have been evaluated and thus

From 3c045c799198406fd8378e2f1c50b73e1e487ea7 Mon Sep 17 00:00:00 2001
From: Cheng Hao <hao.cheng@intel.com>
Date: Mon, 28 Apr 2014 11:09:58 +0800
Subject: [PATCH 02/12] Optimize the Constant Folding by adding more rules

---
 .../sql/catalyst/expressions/Expression.scala |  1 -
 .../sql/catalyst/optimizer/Optimizer.scala    | 28 ++++++-------------
 .../org/apache/spark/sql/hive/hiveUdfs.scala  | 11 ++++++++
 3 files changed, 20 insertions(+), 20 deletions(-)

diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Expression.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Expression.scala
index dd9332ada80dd..41398ff956edd 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Expression.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Expression.scala
@@ -44,7 +44,6 @@ abstract class Expression extends TreeNode[Expression] {
    *  - A [[expressions.Cast Cast]] or [[expressions.UnaryMinus UnaryMinus]] is foldable if its
    *    child is foldable.
    */
-  // TODO: Supporting more foldable expressions. For example, deterministic Hive UDFs.
   def foldable: Boolean = false
   def nullable: Boolean
   def references: Set[Attribute]
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
index e11155539fd75..520101802e25b 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
@@ -94,25 +94,9 @@ object ConstantFolding extends Rule[LogicalPlan] {
     case q: LogicalPlan => q transformExpressionsDown {
       // Skip redundant folding of literals.
       case l: Literal => l
-      case e @ If(Literal(v, _), trueValue, falseValue) => if(v == true) trueValue else falseValue
-      case e @ In(Literal(v, _), list) if(list.exists(c => c match {
-          case Literal(candidate, _) if(candidate == v) => true
-          case _ => false
-        })) => Literal(true, BooleanType)
-      case e if e.foldable => Literal(e.eval(null), e.dataType)
-    }
-  }
-}
-
-/**
- * The expression may be constant value, due to one or more of its children expressions is null or 
- * not null constantly, replaces [[catalyst.expressions.Expression Expressions]] with equivalent 
- * [[catalyst.expressions.Literal Literal]] values if possible caused by that. 
- */
-object NullPropagation extends Rule[LogicalPlan] {
-  def apply(plan: LogicalPlan): LogicalPlan = plan transform {
-    case q: LogicalPlan => q transformExpressionsUp {
-      case l: Literal => l
+      case e @ Count(Literal(null, _)) => Literal(null, e.dataType)
+      case e @ Sum(Literal(null, _)) => Literal(null, e.dataType)
+      case e @ Average(Literal(null, _)) => Literal(null, e.dataType)
       case e @ IsNull(Literal(null, _)) => Literal(true, BooleanType)
       case e @ IsNull(Literal(_, _)) => Literal(false, BooleanType)
       case e @ IsNull(c @ Rand) => Literal(false, BooleanType)
@@ -135,6 +119,11 @@ object NullPropagation extends Rule[LogicalPlan] {
           Coalesce(newChildren)
         }
       }
+      case e @ If(Literal(v, _), trueValue, falseValue) => if(v == true) trueValue else falseValue
+      case e @ In(Literal(v, _), list) if(list.exists(c => c match {
+          case Literal(candidate, _) if(candidate == v) => true
+          case _ => false
+        })) => Literal(true, BooleanType)
       // TODO put exceptional cases(Unary & Binary Expression) before here.
       case e: UnaryExpression => e.child match {
         case Literal(null, _) => Literal(null, e.dataType)
@@ -143,6 +132,7 @@ object NullPropagation extends Rule[LogicalPlan] {
         case Literal(null, _) :: right :: Nil => Literal(null, e.dataType)
         case left :: Literal(null, _) :: Nil => Literal(null, e.dataType)
       }
+      case e if e.foldable => Literal(e.eval(null), e.dataType)
     }
   }
 }
diff --git a/sql/hive/src/main/scala/org/apache/spark/sql/hive/hiveUdfs.scala b/sql/hive/src/main/scala/org/apache/spark/sql/hive/hiveUdfs.scala
index a09270eb7b134..a4e83c8357439 100644
--- a/sql/hive/src/main/scala/org/apache/spark/sql/hive/hiveUdfs.scala
+++ b/sql/hive/src/main/scala/org/apache/spark/sql/hive/hiveUdfs.scala
@@ -22,6 +22,7 @@ import scala.collection.mutable.ArrayBuffer
 import org.apache.hadoop.hive.common.`type`.HiveDecimal
 import org.apache.hadoop.hive.ql.exec.UDF
 import org.apache.hadoop.hive.ql.exec.{FunctionInfo, FunctionRegistry}
+import org.apache.hadoop.hive.ql.udf.{UDFType => HiveUDFType}
 import org.apache.hadoop.hive.ql.udf.generic._
 import org.apache.hadoop.hive.serde2.objectinspector._
 import org.apache.hadoop.hive.serde2.objectinspector.primitive._
@@ -213,6 +214,16 @@ private[hive] case class HiveGenericUdf(name: String, children: Seq[Expression])
 
   @transient
   protected lazy val returnInspector = function.initialize(argumentInspectors.toArray)
+	
+  @transient
+  protected lazy val isUDFDeterministic = {
+    val udfType = function.getClass().getAnnotation(classOf[HiveUDFType])
+    (udfType != null && udfType.deterministic())
+  }
+
+  override def foldable = {
+    isUDFDeterministic && children.foldLeft(true)((prev, n) => prev && n.foldable)
+  }
 
   val dataType: DataType = inspectorToDataType(returnInspector)
 

From 536c005f787e5f56bedbae8946603afbc8d6285e Mon Sep 17 00:00:00 2001
From: Cheng Hao <hao.cheng@intel.com>
Date: Mon, 28 Apr 2014 13:53:51 +0800
Subject: [PATCH 03/12] Add Exceptional case for constant folding

---
 .../spark/sql/catalyst/expressions/complexTypes.scala |  4 +++-
 .../spark/sql/catalyst/optimizer/Optimizer.scala      | 11 ++++++++---
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/complexTypes.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/complexTypes.scala
index c947155cb701c..0add35c971f43 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/complexTypes.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/complexTypes.scala
@@ -28,6 +28,7 @@ case class GetItem(child: Expression, ordinal: Expression) extends Expression {
   val children = child :: ordinal :: Nil
   /** `Null` is returned for invalid ordinals. */
   override def nullable = true
+  override def foldable = child.foldable && ordinal.foldable
   override def references = children.flatMap(_.references).toSet
   def dataType = child.dataType match {
     case ArrayType(dt) => dt
@@ -69,7 +70,8 @@ case class GetField(child: Expression, fieldName: String) extends UnaryExpressio
   type EvaluatedType = Any
 
   def dataType = field.dataType
-  def nullable = field.nullable
+  override def nullable = field.nullable
+  override def foldable = child.foldable
 
   protected def structType = child.dataType match {
     case s: StructType => s
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
index 520101802e25b..aea984cf69de7 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
@@ -91,9 +91,11 @@ object ColumnPruning extends Rule[LogicalPlan] {
  */
 object ConstantFolding extends Rule[LogicalPlan] {
   def apply(plan: LogicalPlan): LogicalPlan = plan transform {
-    case q: LogicalPlan => q transformExpressionsDown {
+    case q: LogicalPlan => q transformExpressionsUp {
       // Skip redundant folding of literals.
       case l: Literal => l
+      // if it's foldable
+      case e if e.foldable => Literal(e.eval(null), e.dataType)
       case e @ Count(Literal(null, _)) => Literal(null, e.dataType)
       case e @ Sum(Literal(null, _)) => Literal(null, e.dataType)
       case e @ Average(Literal(null, _)) => Literal(null, e.dataType)
@@ -124,15 +126,18 @@ object ConstantFolding extends Rule[LogicalPlan] {
           case Literal(candidate, _) if(candidate == v) => true
           case _ => false
         })) => Literal(true, BooleanType)
-      // TODO put exceptional cases(Unary & Binary Expression) before here.
+
+      case e @ SortOrder(_, _) => e
+      // put exceptional cases(Unary & Binary Expression) before here.
       case e: UnaryExpression => e.child match {
         case Literal(null, _) => Literal(null, e.dataType)
+        case _ => e
       }
       case e: BinaryExpression => e.children match {
         case Literal(null, _) :: right :: Nil => Literal(null, e.dataType)
         case left :: Literal(null, _) :: Nil => Literal(null, e.dataType)
+        case _ => e
       }
-      case e if e.foldable => Literal(e.eval(null), e.dataType)
     }
   }
 }

From 9cf039607c518a4c120c1d23b5f01be1018578c4 Mon Sep 17 00:00:00 2001
From: Cheng Hao <hao.cheng@intel.com>
Date: Mon, 28 Apr 2014 16:11:46 +0800
Subject: [PATCH 04/12] update code according to the code review comment

---
 .../sql/catalyst/expressions/Expression.scala | 10 ++++++
 .../sql/catalyst/expressions/SortOrder.scala  |  6 +++-
 .../sql/catalyst/optimizer/Optimizer.scala    | 36 +++++++++++--------
 3 files changed, 37 insertions(+), 15 deletions(-)

diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Expression.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Expression.scala
index 41398ff956edd..0ce68efe24c5d 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Expression.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Expression.scala
@@ -222,6 +222,11 @@ abstract class Expression extends TreeNode[Expression] {
   }
 }
 
+/**
+ * Root class for rewritten 2 operands UDF expression. By default, we assume it produces Null if 
+ * either one of its operands is null. Exceptional case requires to update the optimization rule 
+ * at [[optimizer.ConstantFolding ConstantFolding]]
+ */
 abstract class BinaryExpression extends Expression with trees.BinaryNode[Expression] {
   self: Product =>
 
@@ -238,6 +243,11 @@ abstract class LeafExpression extends Expression with trees.LeafNode[Expression]
   self: Product =>
 }
 
+/**
+ * Root class for rewritten single operand UDF expression. By default, we assume it produces Null if 
+ * its operand is null. Exceptional case requires to update the optimization rule 
+ * at [[optimizer.ConstantFolding ConstantFolding]]
+ */
 abstract class UnaryExpression extends Expression with trees.UnaryNode[Expression] {
   self: Product =>
 
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/SortOrder.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/SortOrder.scala
index 08b2f11d20f5e..d2b7685e73065 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/SortOrder.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/SortOrder.scala
@@ -18,6 +18,7 @@
 package org.apache.spark.sql.catalyst.expressions
 
 import org.apache.spark.sql.catalyst.errors.TreeNodeException
+import org.apache.spark.sql.catalyst.trees
 
 abstract sealed class SortDirection
 case object Ascending extends SortDirection
@@ -27,7 +28,10 @@ case object Descending extends SortDirection
  * An expression that can be used to sort a tuple.  This class extends expression primarily so that
  * transformations over expression will descend into its child.
  */
-case class SortOrder(child: Expression, direction: SortDirection) extends UnaryExpression {
+case class SortOrder(child: Expression, direction: SortDirection) extends Expression 
+    with trees.UnaryNode[Expression] {
+
+  override def references = child.references
   override def dataType = child.dataType
   override def nullable = child.nullable
 
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
index aea984cf69de7..535ac1c3d56ad 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
@@ -26,6 +26,7 @@ import org.apache.spark.sql.catalyst.types._
 object Optimizer extends RuleExecutor[LogicalPlan] {
   val batches =
     Batch("ConstantFolding", Once,
+      NullPropagation,
       ConstantFolding,
       BooleanSimplification,
       SimplifyFilters,
@@ -87,23 +88,18 @@ object ColumnPruning extends Rule[LogicalPlan] {
 
 /**
  * Replaces [[catalyst.expressions.Expression Expressions]] that can be statically evaluated with
- * equivalent [[catalyst.expressions.Literal Literal]] values.
+ * equivalent [[catalyst.expressions.Literal Literal]] values. This rule is more specific with 
+ * Null value propagation from bottom to top of the expression tree.
  */
-object ConstantFolding extends Rule[LogicalPlan] {
+object NullPropagation extends Rule[LogicalPlan] {
   def apply(plan: LogicalPlan): LogicalPlan = plan transform {
     case q: LogicalPlan => q transformExpressionsUp {
       // Skip redundant folding of literals.
       case l: Literal => l
-      // if it's foldable
-      case e if e.foldable => Literal(e.eval(null), e.dataType)
       case e @ Count(Literal(null, _)) => Literal(null, e.dataType)
       case e @ Sum(Literal(null, _)) => Literal(null, e.dataType)
       case e @ Average(Literal(null, _)) => Literal(null, e.dataType)
-      case e @ IsNull(Literal(null, _)) => Literal(true, BooleanType)
-      case e @ IsNull(Literal(_, _)) => Literal(false, BooleanType)
       case e @ IsNull(c @ Rand) => Literal(false, BooleanType)
-      case e @ IsNotNull(Literal(null, _)) => Literal(false, BooleanType)
-      case e @ IsNotNull(Literal(_, _)) => Literal(true, BooleanType)
       case e @ IsNotNull(c @ Rand) => Literal(true, BooleanType)
       case e @ GetItem(Literal(null, _), _) => Literal(null, e.dataType)
       case e @ GetItem(_, Literal(null, _)) => Literal(null, e.dataType)
@@ -113,10 +109,10 @@ object ConstantFolding extends Rule[LogicalPlan] {
           case Literal(null, _) => false
           case _ => true
         })
-        if(newChildren.length == null) {
+        if(newChildren.length == 0) {
           Literal(null, e.dataType)
-        } else if(newChildren.length == children.length){
-          e
+        } else if(newChildren.length == 1) {
+          newChildren(0)
         } else {
           Coalesce(newChildren)
         }
@@ -126,9 +122,8 @@ object ConstantFolding extends Rule[LogicalPlan] {
           case Literal(candidate, _) if(candidate == v) => true
           case _ => false
         })) => Literal(true, BooleanType)
-
-      case e @ SortOrder(_, _) => e
-      // put exceptional cases(Unary & Binary Expression) before here.
+      // Put exceptional cases(Unary & Binary Expression if it doesn't produce null with constant 
+      // null operand) before here.
       case e: UnaryExpression => e.child match {
         case Literal(null, _) => Literal(null, e.dataType)
         case _ => e
@@ -141,6 +136,19 @@ object ConstantFolding extends Rule[LogicalPlan] {
     }
   }
 }
+/**
+ * Replaces [[catalyst.expressions.Expression Expressions]] that can be statically evaluated with
+ * equivalent [[catalyst.expressions.Literal Literal]] values.
+ */
+object ConstantFolding extends Rule[LogicalPlan] {
+  def apply(plan: LogicalPlan): LogicalPlan = plan transform {
+    case q: LogicalPlan => q transformExpressionsDown {
+      // Skip redundant folding of literals.
+      case l: Literal => l
+      case e if e.foldable => Literal(e.eval(null), e.dataType)
+    }
+  }
+}
 
 /**
  * Simplifies boolean expressions where the answer can be determined without evaluating both sides.

From 543ef9dc3af1ef2b7f66c7d98a107dd97cdf2d31 Mon Sep 17 00:00:00 2001
From: Cheng Hao <hao.cheng@intel.com>
Date: Tue, 29 Apr 2014 08:13:21 +0800
Subject: [PATCH 05/12] fix code style issues

---
 .../apache/spark/sql/catalyst/expressions/Expression.scala    | 4 ++--
 .../src/main/scala/org/apache/spark/sql/hive/hiveUdfs.scala   | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Expression.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Expression.scala
index 0ce68efe24c5d..4f6057f873d51 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Expression.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Expression.scala
@@ -244,8 +244,8 @@ abstract class LeafExpression extends Expression with trees.LeafNode[Expression]
 }
 
 /**
- * Root class for rewritten single operand UDF expression. By default, we assume it produces Null if 
- * its operand is null. Exceptional case requires to update the optimization rule 
+ * Root class for rewritten single operand UDF expression. By default, we assume it produces Null 
+ * if its operand is null. Exceptional case requires to update the optimization rule 
  * at [[optimizer.ConstantFolding ConstantFolding]]
  */
 abstract class UnaryExpression extends Expression with trees.UnaryNode[Expression] {
diff --git a/sql/hive/src/main/scala/org/apache/spark/sql/hive/hiveUdfs.scala b/sql/hive/src/main/scala/org/apache/spark/sql/hive/hiveUdfs.scala
index a4e83c8357439..66d9b0dc559d4 100644
--- a/sql/hive/src/main/scala/org/apache/spark/sql/hive/hiveUdfs.scala
+++ b/sql/hive/src/main/scala/org/apache/spark/sql/hive/hiveUdfs.scala
@@ -214,7 +214,7 @@ private[hive] case class HiveGenericUdf(name: String, children: Seq[Expression])
 
   @transient
   protected lazy val returnInspector = function.initialize(argumentInspectors.toArray)
-	
+
   @transient
   protected lazy val isUDFDeterministic = {
     val udfType = function.getClass().getAnnotation(classOf[HiveUDFType])

From 9ccefdbc528ec361dac7552df08f0587be5551e6 Mon Sep 17 00:00:00 2001
From: Michael Armbrust <michael@databricks.com>
Date: Tue, 29 Apr 2014 16:55:59 -0700
Subject: [PATCH 06/12] Add tests for optimized expression evaluation.

---
 .../ExpressionEvaluationSuite.scala           |  4 +--
 .../ExpressionOptimizationSuite.scala         | 36 +++++++++++++++++++
 2 files changed, 37 insertions(+), 3 deletions(-)
 create mode 100644 sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/optimizer/ExpressionOptimizationSuite.scala

diff --git a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/ExpressionEvaluationSuite.scala b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/ExpressionEvaluationSuite.scala
index d287ad73b9e9f..5050dbfadd018 100644
--- a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/ExpressionEvaluationSuite.scala
+++ b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/ExpressionEvaluationSuite.scala
@@ -108,9 +108,7 @@ class ExpressionEvaluationSuite extends FunSuite {
       truthTable.foreach {
         case (l,r,answer) =>
           val expr = op(Literal(l, BooleanType), Literal(r, BooleanType))
-          val result = expr.eval(null)
-          if (result != answer)
-            fail(s"$expr should not evaluate to $result, expected: $answer")
+          checkEvaluation(expr, answer)
       }
     }
   }
diff --git a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/optimizer/ExpressionOptimizationSuite.scala b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/optimizer/ExpressionOptimizationSuite.scala
new file mode 100644
index 0000000000000..890d6289b9dfb
--- /dev/null
+++ b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/optimizer/ExpressionOptimizationSuite.scala
@@ -0,0 +1,36 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.spark.sql.catalyst.optimizer
+
+import org.apache.spark.sql.catalyst.expressions._
+import org.apache.spark.sql.catalyst.plans.logical._
+
+/**
+ * Overrides our expression evaluation tests and reruns them after optimization has occured.  This
+ * is to ensure that constant folding and other optimizations do not break anything.
+ */
+class ExpressionOptimizationSuite extends ExpressionEvaluationSuite {
+  override def checkEvaluation(
+      expression: Expression,
+      expected: Any,
+      inputRow: Row = EmptyRow): Unit = {
+    val plan = Project(Alias(expression, s"Optimized($expression)")() :: Nil, NoRelation)
+    val optimizedPlan = Optimizer(plan)
+    super.checkEvaluation(optimizedPlan.expressions.head, expected, inputRow)
+  }
+}
\ No newline at end of file

From 27ea3d7364017b7f647b04f90f8f3050d236f308 Mon Sep 17 00:00:00 2001
From: Cheng Hao <hao.cheng@intel.com>
Date: Wed, 30 Apr 2014 13:47:36 +0800
Subject: [PATCH 07/12] Fix Constant Folding Bugs & Add More Unittests

---
 .../spark/sql/catalyst/dsl/package.scala      |  22 +--
 .../sql/catalyst/expressions/Expression.scala |  10 --
 .../catalyst/expressions/complexTypes.scala   |  36 +++--
 .../sql/catalyst/optimizer/Optimizer.scala    |  33 ++++-
 .../ExpressionEvaluationSuite.scala           | 133 ++++++++++++++++--
 5 files changed, 182 insertions(+), 52 deletions(-)

diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/dsl/package.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/dsl/package.scala
index 987befe8e22ee..dc83485df195c 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/dsl/package.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/dsl/package.scala
@@ -114,37 +114,37 @@ package object dsl {
       def attr = analysis.UnresolvedAttribute(s)
 
       /** Creates a new AttributeReference of type boolean */
-      def boolean = AttributeReference(s, BooleanType, nullable = false)()
+      def boolean = AttributeReference(s, BooleanType, nullable = true)()
 
       /** Creates a new AttributeReference of type byte */
-      def byte = AttributeReference(s, ByteType, nullable = false)()
+      def byte = AttributeReference(s, ByteType, nullable = true)()
 
       /** Creates a new AttributeReference of type short */
-      def short = AttributeReference(s, ShortType, nullable = false)()
+      def short = AttributeReference(s, ShortType, nullable = true)()
 
       /** Creates a new AttributeReference of type int */
-      def int = AttributeReference(s, IntegerType, nullable = false)()
+      def int = AttributeReference(s, IntegerType, nullable = true)()
 
       /** Creates a new AttributeReference of type long */
-      def long = AttributeReference(s, LongType, nullable = false)()
+      def long = AttributeReference(s, LongType, nullable = true)()
 
       /** Creates a new AttributeReference of type float */
-      def float = AttributeReference(s, FloatType, nullable = false)()
+      def float = AttributeReference(s, FloatType, nullable = true)()
 
       /** Creates a new AttributeReference of type double */
-      def double = AttributeReference(s, DoubleType, nullable = false)()
+      def double = AttributeReference(s, DoubleType, nullable = true)()
 
       /** Creates a new AttributeReference of type string */
-      def string = AttributeReference(s, StringType, nullable = false)()
+      def string = AttributeReference(s, StringType, nullable = true)()
 
       /** Creates a new AttributeReference of type decimal */
-      def decimal = AttributeReference(s, DecimalType, nullable = false)()
+      def decimal = AttributeReference(s, DecimalType, nullable = true)()
 
       /** Creates a new AttributeReference of type timestamp */
-      def timestamp = AttributeReference(s, TimestampType, nullable = false)()
+      def timestamp = AttributeReference(s, TimestampType, nullable = true)()
 
       /** Creates a new AttributeReference of type binary */
-      def binary = AttributeReference(s, BinaryType, nullable = false)()
+      def binary = AttributeReference(s, BinaryType, nullable = true)()
     }
 
     implicit class DslAttribute(a: AttributeReference) {
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Expression.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Expression.scala
index 4f6057f873d51..41398ff956edd 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Expression.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Expression.scala
@@ -222,11 +222,6 @@ abstract class Expression extends TreeNode[Expression] {
   }
 }
 
-/**
- * Root class for rewritten 2 operands UDF expression. By default, we assume it produces Null if 
- * either one of its operands is null. Exceptional case requires to update the optimization rule 
- * at [[optimizer.ConstantFolding ConstantFolding]]
- */
 abstract class BinaryExpression extends Expression with trees.BinaryNode[Expression] {
   self: Product =>
 
@@ -243,11 +238,6 @@ abstract class LeafExpression extends Expression with trees.LeafNode[Expression]
   self: Product =>
 }
 
-/**
- * Root class for rewritten single operand UDF expression. By default, we assume it produces Null 
- * if its operand is null. Exceptional case requires to update the optimization rule 
- * at [[optimizer.ConstantFolding ConstantFolding]]
- */
 abstract class UnaryExpression extends Expression with trees.UnaryNode[Expression] {
   self: Product =>
 
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/complexTypes.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/complexTypes.scala
index 0add35c971f43..fd5aee51f926a 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/complexTypes.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/complexTypes.scala
@@ -41,23 +41,33 @@ case class GetItem(child: Expression, ordinal: Expression) extends Expression {
   override def toString = s"$child[$ordinal]"
 
   override def eval(input: Row): Any = {
-    if (child.dataType.isInstanceOf[ArrayType]) {
-      val baseValue = child.eval(input).asInstanceOf[Seq[_]]
-      val o = ordinal.eval(input).asInstanceOf[Int]
-      if (baseValue == null) {
-        null
-      } else if (o >= baseValue.size || o < 0) {
-        null
-      } else {
-        baseValue(o)
-      }
+    val value = child.eval(input)
+    if(value == null) {
+      null
     } else {
-      val baseValue = child.eval(input).asInstanceOf[Map[Any, _]]
       val key = ordinal.eval(input)
-      if (baseValue == null) {
+      if(key == null) {
         null
       } else {
-        baseValue.get(key).orNull
+        if (child.dataType.isInstanceOf[ArrayType]) {
+          val baseValue = value.asInstanceOf[Seq[_]]
+          val o = key.asInstanceOf[Int]
+          if (baseValue == null) {
+            null
+          } else if (o >= baseValue.size || o < 0) {
+            null
+          } else {
+            baseValue(o)
+          }
+        } else {
+          val baseValue = value.asInstanceOf[Map[Any, _]]
+          val key = ordinal.eval(input)
+          if (baseValue == null) {
+            null
+          } else {
+            baseValue.get(key).orNull
+          }
+        }
       }
     }
   }
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
index 535ac1c3d56ad..f4f9b36cbcb4c 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
@@ -96,11 +96,11 @@ object NullPropagation extends Rule[LogicalPlan] {
     case q: LogicalPlan => q transformExpressionsUp {
       // Skip redundant folding of literals.
       case l: Literal => l
-      case e @ Count(Literal(null, _)) => Literal(null, e.dataType)
+      case e @ Count(Literal(null, _)) => Literal(0, e.dataType)
       case e @ Sum(Literal(null, _)) => Literal(null, e.dataType)
       case e @ Average(Literal(null, _)) => Literal(null, e.dataType)
-      case e @ IsNull(c @ Rand) => Literal(false, BooleanType)
-      case e @ IsNotNull(c @ Rand) => Literal(true, BooleanType)
+      case e @ IsNull(c) if c.nullable == false => Literal(false, BooleanType)
+      case e @ IsNotNull(c) if c.nullable == false => Literal(true, BooleanType)
       case e @ GetItem(Literal(null, _), _) => Literal(null, e.dataType)
       case e @ GetItem(_, Literal(null, _)) => Literal(null, e.dataType)
       case e @ GetField(Literal(null, _), _) => Literal(null, e.dataType)
@@ -122,13 +122,32 @@ object NullPropagation extends Rule[LogicalPlan] {
           case Literal(candidate, _) if(candidate == v) => true
           case _ => false
         })) => Literal(true, BooleanType)
-      // Put exceptional cases(Unary & Binary Expression if it doesn't produce null with constant 
-      // null operand) before here.
-      case e: UnaryExpression => e.child match {
+      case e: UnaryMinus => e.child match {
         case Literal(null, _) => Literal(null, e.dataType)
         case _ => e
       }
-      case e: BinaryExpression => e.children match {
+      case e: Cast => e.child match {
+        case Literal(null, _) => Literal(null, e.dataType)
+        case _ => e
+      }
+      case e: Not => e.child match {
+        case Literal(null, _) => Literal(null, e.dataType)
+        case _ => e
+      }
+      case e: And => e // leave it for BooleanSimplification
+      case e: Or => e  // leave it for BooleanSimplification
+      // Put exceptional cases above
+      case e: BinaryArithmetic => e.children match {
+        case Literal(null, _) :: right :: Nil => Literal(null, e.dataType)
+        case left :: Literal(null, _) :: Nil => Literal(null, e.dataType)
+        case _ => e
+      }
+      case e: BinaryPredicate => e.children match {
+        case Literal(null, _) :: right :: Nil => Literal(null, e.dataType)
+        case left :: Literal(null, _) :: Nil => Literal(null, e.dataType)
+        case _ => e
+      }
+      case e: StringRegexExpression => e.children match {
         case Literal(null, _) :: right :: Nil => Literal(null, e.dataType)
         case left :: Literal(null, _) :: Nil => Literal(null, e.dataType)
         case _ => e
diff --git a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/ExpressionEvaluationSuite.scala b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/ExpressionEvaluationSuite.scala
index 5050dbfadd018..cc6df1088e737 100644
--- a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/ExpressionEvaluationSuite.scala
+++ b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/ExpressionEvaluationSuite.scala
@@ -129,6 +129,7 @@ class ExpressionEvaluationSuite extends FunSuite {
 
   test("LIKE literal Regular Expression") {
     checkEvaluation(Literal(null, StringType).like("a"), null)
+    checkEvaluation(Literal("a", StringType).like(Literal(null, StringType)), null)
     checkEvaluation(Literal(null, StringType).like(Literal(null, StringType)), null)
     checkEvaluation("abdef" like "abdef", true)
     checkEvaluation("a_%b" like "a\\__b", true)
@@ -157,9 +158,14 @@ class ExpressionEvaluationSuite extends FunSuite {
     checkEvaluation("abc" like regEx, true, new GenericRow(Array[Any]("a%")))
     checkEvaluation("abc" like regEx, false, new GenericRow(Array[Any]("b%")))
     checkEvaluation("abc" like regEx, false, new GenericRow(Array[Any]("bc%")))
+    
+    checkEvaluation(Literal(null, StringType) like regEx, null, new GenericRow(Array[Any]("bc%")))
   }
 
   test("RLIKE literal Regular Expression") {
+    checkEvaluation(Literal(null, StringType) rlike "abdef", null)
+    checkEvaluation("abdef" rlike Literal(null, StringType), null)
+    checkEvaluation(Literal(null, StringType) rlike Literal(null, StringType), null)
     checkEvaluation("abdef" rlike "abdef", true)
     checkEvaluation("abbbbc" rlike "a.*c", true)
 
@@ -244,17 +250,19 @@ class ExpressionEvaluationSuite extends FunSuite {
 
     intercept[Exception] {evaluate(Literal(1) cast BinaryType, null)}
 
-    assert(("abcdef" cast StringType).nullable === false)
-    assert(("abcdef" cast BinaryType).nullable === false)
-    assert(("abcdef" cast BooleanType).nullable === false)
-    assert(("abcdef" cast TimestampType).nullable === true)
-    assert(("abcdef" cast LongType).nullable === true)
-    assert(("abcdef" cast IntegerType).nullable === true)
-    assert(("abcdef" cast ShortType).nullable === true)
-    assert(("abcdef" cast ByteType).nullable === true)
-    assert(("abcdef" cast DecimalType).nullable === true)
-    assert(("abcdef" cast DoubleType).nullable === true)
-    assert(("abcdef" cast FloatType).nullable === true)
+    checkEvaluation(("abcdef" cast StringType).nullable, false)
+    checkEvaluation(("abcdef" cast BinaryType).nullable,false)
+    checkEvaluation(("abcdef" cast BooleanType).nullable, false)
+    checkEvaluation(("abcdef" cast TimestampType).nullable, true)
+    checkEvaluation(("abcdef" cast LongType).nullable, true)
+    checkEvaluation(("abcdef" cast IntegerType).nullable, true)
+    checkEvaluation(("abcdef" cast ShortType).nullable, true)
+    checkEvaluation(("abcdef" cast ByteType).nullable, true)
+    checkEvaluation(("abcdef" cast DecimalType).nullable, true)
+    checkEvaluation(("abcdef" cast DoubleType).nullable, true)
+    checkEvaluation(("abcdef" cast FloatType).nullable, true)
+
+    checkEvaluation(Cast(Literal(null, IntegerType), ShortType), null)
   }
 
   test("timestamp") {
@@ -285,5 +293,108 @@ class ExpressionEvaluationSuite extends FunSuite {
     // A test for higher precision than millis
     checkEvaluation(Cast(Cast(0.00000001, TimestampType), DoubleType), 0.00000001)
   }
+  
+  test("null checking") {
+    val row = new GenericRow(Array[Any]("^Ba*n", null, true, null))
+    val c1 = 'a.string.at(0)
+    val c2 = 'a.string.at(1)
+    val c3 = 'a.boolean.at(2)
+    val c4 = 'a.boolean.at(3)
+
+    checkEvaluation(IsNull(c1), false, row)
+    checkEvaluation(IsNotNull(c1), true, row)
+
+    checkEvaluation(IsNull(c2), true, row)
+    checkEvaluation(IsNotNull(c2), false, row)
+
+    checkEvaluation(IsNull(Literal(1, ShortType)), false)
+    checkEvaluation(IsNotNull(Literal(1, ShortType)), true)
+
+    checkEvaluation(IsNull(Literal(null, ShortType)), true)
+    checkEvaluation(IsNotNull(Literal(null, ShortType)), false)
+    
+    checkEvaluation(Coalesce(c1 :: c2 :: Nil), "^Ba*n", row)
+    checkEvaluation(Coalesce(Literal(null, StringType) :: Nil), null, row)
+    checkEvaluation(Coalesce(Literal(null, StringType) :: c1 :: c2 :: Nil), "^Ba*n", row)
+
+    checkEvaluation(If(c3, Literal("a", StringType), Literal("b", StringType)), "a", row)
+    checkEvaluation(If(c3, c1, c2), "^Ba*n", row)
+    checkEvaluation(If(c4, c2, c1), "^Ba*n", row)
+    checkEvaluation(If(Literal(null, BooleanType), c2, c1), "^Ba*n", row)
+    checkEvaluation(If(Literal(true, BooleanType), c1, c2), "^Ba*n", row)
+    checkEvaluation(If(Literal(false, BooleanType), c2, c1), "^Ba*n", row)
+    checkEvaluation(If(Literal(false, BooleanType), 
+      Literal("a", StringType), Literal("b", StringType)), "b", row)
+
+    checkEvaluation(In(c1, c1 :: c2 :: Nil), true, row)
+    checkEvaluation(In(Literal("^Ba*n", StringType), 
+      Literal("^Ba*n", StringType) :: Nil), true, row)
+    checkEvaluation(In(Literal("^Ba*n", StringType),
+      Literal("^Ba*n", StringType) :: c2 :: Nil), true, row)
+  }
+
+  test("complex type") {
+    val row = new GenericRow(Array[Any](
+      "^Ba*n",                                  // 0 
+      null.asInstanceOf[String],                // 1
+      new GenericRow(Array[Any]("aa", "bb")),   // 2
+      Map("aa"->"bb"),                          // 3
+      Seq("aa", "bb")                           // 4
+    ))
+
+    val typeS = StructType(
+      StructField("a", StringType, true) :: StructField("b", StringType, true) :: Nil
+    )
+    val typeMap = MapType(StringType, StringType)
+    val typeArray = ArrayType(StringType)
+
+    checkEvaluation(GetItem(BoundReference(3, AttributeReference("c", typeMap)()), 
+      Literal("aa")), "bb", row)
+    checkEvaluation(GetItem(Literal(null, typeMap), Literal("aa")), null, row)
+    checkEvaluation(GetItem(Literal(null, typeMap), Literal(null, StringType)), null, row)
+    checkEvaluation(GetItem(BoundReference(3, AttributeReference("c", typeMap)()), 
+      Literal(null, StringType)), null, row)
+
+    checkEvaluation(GetItem(BoundReference(4, AttributeReference("c", typeArray)()), 
+      Literal(1)), "bb", row)
+    checkEvaluation(GetItem(Literal(null, typeArray), Literal(1)), null, row)
+    checkEvaluation(GetItem(Literal(null, typeArray), Literal(null, IntegerType)), null, row)
+    checkEvaluation(GetItem(BoundReference(4, AttributeReference("c", typeArray)()), 
+      Literal(null, IntegerType)), null, row)
+
+    checkEvaluation(GetField(BoundReference(2, AttributeReference("c", typeS)()), "a"), "aa", row)
+    checkEvaluation(GetField(Literal(null, typeS), "a"), null, row)
+  }
+
+  test("arithmetic") {
+    val row = new GenericRow(Array[Any](1, 2, 3, null))
+    val c1 = 'a.int.at(0)
+    val c2 = 'a.int.at(1)
+    val c3 = 'a.int.at(2)
+    val c4 = 'a.int.at(3)
+
+    checkEvaluation(UnaryMinus(c1), -1, row)
+    checkEvaluation(UnaryMinus(Literal(100, IntegerType)), -100)
+
+    checkEvaluation(Add(c1, c4), null, row)
+    checkEvaluation(Add(c1, c2), 3, row)
+    checkEvaluation(Add(c1, Literal(null, IntegerType)), null, row)
+    checkEvaluation(Add(Literal(null, IntegerType), c2), null, row)
+    checkEvaluation(Add(Literal(null, IntegerType), Literal(null, IntegerType)), null, row)
+  }
+
+  test("BinaryComparison") {
+    val row = new GenericRow(Array[Any](1, 2, 3, null))
+    val c1 = 'a.int.at(0)
+    val c2 = 'a.int.at(1)
+    val c3 = 'a.int.at(2)
+    val c4 = 'a.int.at(3)
+
+    checkEvaluation(LessThan(c1, c4), null, row)
+    checkEvaluation(LessThan(c1, c2), true, row)
+    checkEvaluation(LessThan(c1, Literal(null, IntegerType)), null, row)
+    checkEvaluation(LessThan(Literal(null, IntegerType), c2), null, row)
+    checkEvaluation(LessThan(Literal(null, IntegerType), Literal(null, IntegerType)), null, row)
+  }
 }
 

From 80f9f1871640c718c6c4b3f627aec99b52b1f96d Mon Sep 17 00:00:00 2001
From: Cheng Hao <hao.cheng@intel.com>
Date: Wed, 30 Apr 2014 14:51:46 +0800
Subject: [PATCH 08/12] Update the UnitTest for aggregation constant folding

---
 .../sql/catalyst/optimizer/Optimizer.scala    |   4 +-
 ...M_COUNT-0-45f5619d9e4510195fe67f7c8d14a5c0 | 309 ++++++++++++++++++
 ...M_COUNT-0-a393cfc24ad74f930f3284743254c10c | 309 ++++++++++++++++++
 ...M_COUNT-0-ae497f1556f548c1e2da9244397a985d | 309 ++++++++++++++++++
 ...M_COUNT-0-c60b6075da793b826db5eb4b08d7bab9 | 309 ++++++++++++++++++
 .../sql/hive/execution/HiveQuerySuite.scala   |   3 +
 6 files changed, 1241 insertions(+), 2 deletions(-)
 create mode 100644 sql/hive/src/test/resources/golden/Constant Folding Optimization for AVG_SUM_COUNT-0-45f5619d9e4510195fe67f7c8d14a5c0
 create mode 100644 sql/hive/src/test/resources/golden/Constant Folding Optimization for AVG_SUM_COUNT-0-a393cfc24ad74f930f3284743254c10c
 create mode 100644 sql/hive/src/test/resources/golden/Constant Folding Optimization for AVG_SUM_COUNT-0-ae497f1556f548c1e2da9244397a985d
 create mode 100644 sql/hive/src/test/resources/golden/Constant Folding Optimization for AVG_SUM_COUNT-0-c60b6075da793b826db5eb4b08d7bab9

diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
index f4f9b36cbcb4c..d38839daf182d 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
@@ -97,8 +97,8 @@ object NullPropagation extends Rule[LogicalPlan] {
       // Skip redundant folding of literals.
       case l: Literal => l
       case e @ Count(Literal(null, _)) => Literal(0, e.dataType)
-      case e @ Sum(Literal(null, _)) => Literal(null, e.dataType)
-      case e @ Average(Literal(null, _)) => Literal(null, e.dataType)
+      case e @ Sum(Literal(c, _)) if(c == 0) => Literal(0, e.dataType)
+      case e @ Average(Literal(c, _)) if(c == 0) => Literal(0.0, e.dataType)
       case e @ IsNull(c) if c.nullable == false => Literal(false, BooleanType)
       case e @ IsNotNull(c) if c.nullable == false => Literal(true, BooleanType)
       case e @ GetItem(Literal(null, _), _) => Literal(null, e.dataType)
diff --git a/sql/hive/src/test/resources/golden/Constant Folding Optimization for AVG_SUM_COUNT-0-45f5619d9e4510195fe67f7c8d14a5c0 b/sql/hive/src/test/resources/golden/Constant Folding Optimization for AVG_SUM_COUNT-0-45f5619d9e4510195fe67f7c8d14a5c0
new file mode 100644
index 0000000000000..7643569a2c234
--- /dev/null
+++ b/sql/hive/src/test/resources/golden/Constant Folding Optimization for AVG_SUM_COUNT-0-45f5619d9e4510195fe67f7c8d14a5c0	
@@ -0,0 +1,309 @@
+0.0	0	0	0	3
+2.0	0	2	0	1
+4.0	0	4	0	1
+5.0	0	15	0	3
+8.0	0	8	0	1
+9.0	0	9	0	1
+10.0	0	10	0	1
+11.0	0	11	0	1
+12.0	0	24	0	2
+15.0	0	30	0	2
+17.0	0	17	0	1
+18.0	0	36	0	2
+19.0	0	19	0	1
+20.0	0	20	0	1
+24.0	0	48	0	2
+26.0	0	52	0	2
+27.0	0	27	0	1
+28.0	0	28	0	1
+30.0	0	30	0	1
+33.0	0	33	0	1
+34.0	0	34	0	1
+35.0	0	105	0	3
+37.0	0	74	0	2
+41.0	0	41	0	1
+42.0	0	84	0	2
+43.0	0	43	0	1
+44.0	0	44	0	1
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diff --git a/sql/hive/src/test/resources/golden/Constant Folding Optimization for AVG_SUM_COUNT-0-a393cfc24ad74f930f3284743254c10c b/sql/hive/src/test/resources/golden/Constant Folding Optimization for AVG_SUM_COUNT-0-a393cfc24ad74f930f3284743254c10c
new file mode 100644
index 0000000000000..f23b45c32ecca
--- /dev/null
+++ b/sql/hive/src/test/resources/golden/Constant Folding Optimization for AVG_SUM_COUNT-0-a393cfc24ad74f930f3284743254c10c	
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diff --git a/sql/hive/src/test/resources/golden/Constant Folding Optimization for AVG_SUM_COUNT-0-ae497f1556f548c1e2da9244397a985d b/sql/hive/src/test/resources/golden/Constant Folding Optimization for AVG_SUM_COUNT-0-ae497f1556f548c1e2da9244397a985d
new file mode 100644
index 0000000000000..7839d714c25d2
--- /dev/null
+++ b/sql/hive/src/test/resources/golden/Constant Folding Optimization for AVG_SUM_COUNT-0-ae497f1556f548c1e2da9244397a985d	
@@ -0,0 +1,309 @@
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diff --git a/sql/hive/src/test/resources/golden/Constant Folding Optimization for AVG_SUM_COUNT-0-c60b6075da793b826db5eb4b08d7bab9 b/sql/hive/src/test/resources/golden/Constant Folding Optimization for AVG_SUM_COUNT-0-c60b6075da793b826db5eb4b08d7bab9
new file mode 100644
index 0000000000000..cd6b14ac2a425
--- /dev/null
+++ b/sql/hive/src/test/resources/golden/Constant Folding Optimization for AVG_SUM_COUNT-0-c60b6075da793b826db5eb4b08d7bab9	
@@ -0,0 +1,309 @@
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diff --git a/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/HiveQuerySuite.scala b/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/HiveQuerySuite.scala
index d224d2ee600ec..87a92d83383ab 100644
--- a/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/HiveQuerySuite.scala
+++ b/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/HiveQuerySuite.scala
@@ -33,6 +33,9 @@ class HiveQuerySuite extends HiveComparisonTest {
     hiveql("FROM src SELECT key").collect()
   }
 
+  createQueryTest("Constant Folding Optimization for AVG_SUM_COUNT",
+    "SELECT AVG(0), SUM(0), COUNT(null), COUNT(value) FROM src GROUP BY key")
+
   createQueryTest("Simple Average",
     "SELECT AVG(key) FROM src")
 

From 50444cc04edafff9e75e41bf06500d7936b178b8 Mon Sep 17 00:00:00 2001
From: Cheng Hao <hao.cheng@intel.com>
Date: Wed, 30 Apr 2014 14:57:22 +0800
Subject: [PATCH 09/12] Remove the unnecessary null checking

---
 .../spark/sql/catalyst/expressions/complexTypes.scala  | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/complexTypes.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/complexTypes.scala
index fd5aee51f926a..13024fd5c71aa 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/complexTypes.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/complexTypes.scala
@@ -52,9 +52,7 @@ case class GetItem(child: Expression, ordinal: Expression) extends Expression {
         if (child.dataType.isInstanceOf[ArrayType]) {
           val baseValue = value.asInstanceOf[Seq[_]]
           val o = key.asInstanceOf[Int]
-          if (baseValue == null) {
-            null
-          } else if (o >= baseValue.size || o < 0) {
+          if (o >= baseValue.size || o < 0) {
             null
           } else {
             baseValue(o)
@@ -62,11 +60,7 @@ case class GetItem(child: Expression, ordinal: Expression) extends Expression {
         } else {
           val baseValue = value.asInstanceOf[Map[Any, _]]
           val key = ordinal.eval(input)
-          if (baseValue == null) {
-            null
-          } else {
-            baseValue.get(key).orNull
-          }
+          baseValue.get(key).orNull
         }
       }
     }

From 29c81665ec6084c015f85081c224f23880adac8b Mon Sep 17 00:00:00 2001
From: Cheng Hao <hao.cheng@intel.com>
Date: Mon, 5 May 2014 08:57:36 +0800
Subject: [PATCH 10/12] Update the code for feedback of code review

---
 .../sql/catalyst/optimizer/Optimizer.scala    |  6 ++---
 .../ExpressionEvaluationSuite.scala           | 22 +++++++++----------
 2 files changed, 13 insertions(+), 15 deletions(-)

diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
index d38839daf182d..573fe047eb589 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
@@ -134,15 +134,13 @@ object NullPropagation extends Rule[LogicalPlan] {
         case Literal(null, _) => Literal(null, e.dataType)
         case _ => e
       }
-      case e: And => e // leave it for BooleanSimplification
-      case e: Or => e  // leave it for BooleanSimplification
-      // Put exceptional cases above
+      // Put exceptional cases above if any
       case e: BinaryArithmetic => e.children match {
         case Literal(null, _) :: right :: Nil => Literal(null, e.dataType)
         case left :: Literal(null, _) :: Nil => Literal(null, e.dataType)
         case _ => e
       }
-      case e: BinaryPredicate => e.children match {
+      case e: BinaryComparison => e.children match {
         case Literal(null, _) :: right :: Nil => Literal(null, e.dataType)
         case left :: Literal(null, _) :: Nil => Literal(null, e.dataType)
         case _ => e
diff --git a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/ExpressionEvaluationSuite.scala b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/ExpressionEvaluationSuite.scala
index cc6df1088e737..91605d0a260e5 100644
--- a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/ExpressionEvaluationSuite.scala
+++ b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/ExpressionEvaluationSuite.scala
@@ -250,17 +250,17 @@ class ExpressionEvaluationSuite extends FunSuite {
 
     intercept[Exception] {evaluate(Literal(1) cast BinaryType, null)}
 
-    checkEvaluation(("abcdef" cast StringType).nullable, false)
-    checkEvaluation(("abcdef" cast BinaryType).nullable,false)
-    checkEvaluation(("abcdef" cast BooleanType).nullable, false)
-    checkEvaluation(("abcdef" cast TimestampType).nullable, true)
-    checkEvaluation(("abcdef" cast LongType).nullable, true)
-    checkEvaluation(("abcdef" cast IntegerType).nullable, true)
-    checkEvaluation(("abcdef" cast ShortType).nullable, true)
-    checkEvaluation(("abcdef" cast ByteType).nullable, true)
-    checkEvaluation(("abcdef" cast DecimalType).nullable, true)
-    checkEvaluation(("abcdef" cast DoubleType).nullable, true)
-    checkEvaluation(("abcdef" cast FloatType).nullable, true)
+    assert(("abcdef" cast StringType).nullable === false)
+    assert(("abcdef" cast BinaryType).nullable === false)
+    assert(("abcdef" cast BooleanType).nullable === false)
+    assert(("abcdef" cast TimestampType).nullable === true)
+    assert(("abcdef" cast LongType).nullable === true)
+    assert(("abcdef" cast IntegerType).nullable === true)
+    assert(("abcdef" cast ShortType).nullable === true)
+    assert(("abcdef" cast ByteType).nullable === true)
+    assert(("abcdef" cast DecimalType).nullable === true)
+    assert(("abcdef" cast DoubleType).nullable === true)
+    assert(("abcdef" cast FloatType).nullable === true)
 
     checkEvaluation(Cast(Literal(null, IntegerType), ShortType), null)
   }

From 68b9fad66b499e667c827a1a0bb1ef8dccaa813e Mon Sep 17 00:00:00 2001
From: Cheng Hao <hao.cheng@intel.com>
Date: Mon, 5 May 2014 09:14:01 +0800
Subject: [PATCH 11/12] Remove the Literal pattern matching for NullPropagation

---
 .../org/apache/spark/sql/catalyst/optimizer/Optimizer.scala     | 2 --
 1 file changed, 2 deletions(-)

diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
index 573fe047eb589..4d2729568ae7c 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
@@ -94,8 +94,6 @@ object ColumnPruning extends Rule[LogicalPlan] {
 object NullPropagation extends Rule[LogicalPlan] {
   def apply(plan: LogicalPlan): LogicalPlan = plan transform {
     case q: LogicalPlan => q transformExpressionsUp {
-      // Skip redundant folding of literals.
-      case l: Literal => l
       case e @ Count(Literal(null, _)) => Literal(0, e.dataType)
       case e @ Sum(Literal(c, _)) if(c == 0) => Literal(0, e.dataType)
       case e @ Average(Literal(c, _)) if(c == 0) => Literal(0.0, e.dataType)

From 2f14b500d360a1a68f5e3d18b73c9a298e36195c Mon Sep 17 00:00:00 2001
From: Cheng Hao <hao.cheng@intel.com>
Date: Tue, 6 May 2014 08:34:14 +0800
Subject: [PATCH 12/12] Fix code style issues

---
 .../sql/catalyst/expressions/complexTypes.scala   |  4 ++--
 .../spark/sql/catalyst/optimizer/Optimizer.scala  | 15 ++++++++-------
 2 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/complexTypes.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/complexTypes.scala
index 13024fd5c71aa..195ca2eb3d589 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/complexTypes.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/complexTypes.scala
@@ -42,11 +42,11 @@ case class GetItem(child: Expression, ordinal: Expression) extends Expression {
 
   override def eval(input: Row): Any = {
     val value = child.eval(input)
-    if(value == null) {
+    if (value == null) {
       null
     } else {
       val key = ordinal.eval(input)
-      if(key == null) {
+      if (key == null) {
         null
       } else {
         if (child.dataType.isInstanceOf[ArrayType]) {
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
index 4d2729568ae7c..3037d45cc6e35 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
@@ -95,8 +95,8 @@ object NullPropagation extends Rule[LogicalPlan] {
   def apply(plan: LogicalPlan): LogicalPlan = plan transform {
     case q: LogicalPlan => q transformExpressionsUp {
       case e @ Count(Literal(null, _)) => Literal(0, e.dataType)
-      case e @ Sum(Literal(c, _)) if(c == 0) => Literal(0, e.dataType)
-      case e @ Average(Literal(c, _)) if(c == 0) => Literal(0.0, e.dataType)
+      case e @ Sum(Literal(c, _)) if c == 0 => Literal(0, e.dataType)
+      case e @ Average(Literal(c, _)) if c == 0 => Literal(0.0, e.dataType)
       case e @ IsNull(c) if c.nullable == false => Literal(false, BooleanType)
       case e @ IsNotNull(c) if c.nullable == false => Literal(true, BooleanType)
       case e @ GetItem(Literal(null, _), _) => Literal(null, e.dataType)
@@ -107,17 +107,17 @@ object NullPropagation extends Rule[LogicalPlan] {
           case Literal(null, _) => false
           case _ => true
         })
-        if(newChildren.length == 0) {
+        if (newChildren.length == 0) {
           Literal(null, e.dataType)
-        } else if(newChildren.length == 1) {
+        } else if (newChildren.length == 1) {
           newChildren(0)
         } else {
           Coalesce(newChildren)
         }
       }
-      case e @ If(Literal(v, _), trueValue, falseValue) => if(v == true) trueValue else falseValue
-      case e @ In(Literal(v, _), list) if(list.exists(c => c match {
-          case Literal(candidate, _) if(candidate == v) => true
+      case e @ If(Literal(v, _), trueValue, falseValue) => if (v == true) trueValue else falseValue
+      case e @ In(Literal(v, _), list) if (list.exists(c => c match {
+          case Literal(candidate, _) if candidate == v => true
           case _ => false
         })) => Literal(true, BooleanType)
       case e: UnaryMinus => e.child match {
@@ -151,6 +151,7 @@ object NullPropagation extends Rule[LogicalPlan] {
     }
   }
 }
+
 /**
  * Replaces [[catalyst.expressions.Expression Expressions]] that can be statically evaluated with
  * equivalent [[catalyst.expressions.Literal Literal]] values.