[SPARK-20586] [SQL] Add deterministic to ScalaUDF

python/pyspark/sql/context.py

@@ -220,11 +220,11 @@ def registerJavaFunction(self, name, javaClassName, returnType=None):
         >>> sqlContext.registerJavaFunction("javaStringLength",
         ...   "test.org.apache.spark.sql.JavaStringLength", IntegerType())
         >>> sqlContext.sql("SELECT javaStringLength('test')").collect()
-        [Row(UDF(test)=4)]
+        [Row(UDF:javaStringLength(test)=4)]
         >>> sqlContext.registerJavaFunction("javaStringLength2",
         ...   "test.org.apache.spark.sql.JavaStringLength")
         >>> sqlContext.sql("SELECT javaStringLength2('test')").collect()
-        [Row(UDF(test)=4)]
+        [Row(UDF:javaStringLength2(test)=4)]
 
         """
         jdt = None

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

@@ -1950,7 +1950,7 @@ class Analyzer(
 
       case p => p transformExpressionsUp {
 
-        case udf @ ScalaUDF(func, _, inputs, _, _, _) =>
+        case udf @ ScalaUDF(func, _, inputs, _, _, _, _) =>
           val parameterTypes = ScalaReflection.getParameterTypes(func)
           assert(parameterTypes.length == inputs.length)
 

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/ScalaUDF.scala

@@ -24,7 +24,6 @@ import org.apache.spark.sql.types.DataType
 
 /**
  * User-defined function.
- * Note that the user-defined functions must be deterministic.
  * @param function  The user defined scala function to run.
  *                  Note that if you use primitive parameters, you are not able to check if it is
  *                  null or not, and the UDF will return null for you if the primitive input is
@@ -35,18 +34,23 @@ import org.apache.spark.sql.types.DataType
  *                    not want to perform coercion, simply use "Nil". Note that it would've been
  *                    better to use Option of Seq[DataType] so we can use "None" as the case for no
  *                    type coercion. However, that would require more refactoring of the codebase.
- * @param udfName   The user-specified name of this UDF.
+ * @param udfName  The user-specified name of this UDF.
  * @param nullable  True if the UDF can return null value.
+ * @param udfDeterministic  True if the UDF is deterministic. Deterministic UDF returns same result
+ *                          each time it is invoked with a particular input.
  */
 case class ScalaUDF(
     function: AnyRef,
     dataType: DataType,
     children: Seq[Expression],
     inputTypes: Seq[DataType] = Nil,
     udfName: Option[String] = None,
-    nullable: Boolean = true)
+    nullable: Boolean = true,
+    udfDeterministic: Boolean = true)
   extends Expression with ImplicitCastInputTypes with NonSQLExpression {
 
+  override def deterministic: Boolean = udfDeterministic && children.forall(_.deterministic)
+
   override def toString: String =
     s"${udfName.map(name => s"UDF:$name").getOrElse("UDF")}(${children.mkString(", ")})"
 

sql/core/src/main/scala/org/apache/spark/sql/expressions/UserDefinedFunction.scala

@@ -20,7 +20,6 @@ package org.apache.spark.sql.expressions
 import org.apache.spark.annotation.InterfaceStability
 import org.apache.spark.sql.catalyst.expressions.ScalaUDF
 import org.apache.spark.sql.Column
-import org.apache.spark.sql.functions
 import org.apache.spark.sql.types.DataType
 
 /**
@@ -35,10 +34,6 @@ import org.apache.spark.sql.types.DataType
  *   df.select( predict(df("score")) )
  * }}}
  *
- * @note The user-defined functions must be deterministic. Due to optimization,
- * duplicate invocations may be eliminated or the function may even be invoked more times than
- * it is present in the query.
- *
  * @since 1.3.0
  */
 @InterfaceStability.Stable
@@ -49,6 +44,7 @@ case class UserDefinedFunction protected[sql] (
 
   private var _nameOption: Option[String] = None
   private var _nullable: Boolean = true
+  private var _deterministic: Boolean = true
 
   /**
    * Returns true when the UDF can return a nullable value.
@@ -57,6 +53,14 @@ case class UserDefinedFunction protected[sql] (
    */
   def nullable: Boolean = _nullable
 
+  /**
+   * Returns true iff the UDF is deterministic, i.e. the UDF produces the same output given the same
+   * input.
+   *
+   * @since 2.3.0
+   */
+  def deterministic: Boolean = _deterministic
+
   /**
    * Returns an expression that invokes the UDF, using the given arguments.
    *
@@ -69,13 +73,15 @@ case class UserDefinedFunction protected[sql] (
       exprs.map(_.expr),
       inputTypes.getOrElse(Nil),
       udfName = _nameOption,
-      nullable = _nullable))
+      nullable = _nullable,
+      udfDeterministic = _deterministic))
   }
 
   private def copyAll(): UserDefinedFunction = {
     val udf = copy()
     udf._nameOption = _nameOption
     udf._nullable = _nullable
+    udf._deterministic = _deterministic
     udf
   }
 
@@ -84,22 +90,38 @@ case class UserDefinedFunction protected[sql] (
    *
    * @since 2.3.0
    */
-  def withName(name: String): this.type = {
-    this._nameOption = Option(name)
-    this
+  def withName(name: String): UserDefinedFunction = {
+    val udf = copyAll()
+    udf._nameOption = Option(name)
+    udf
+  }
+
+  /**
+   * Updates UserDefinedFunction to non-nullable.
+   *
+   * @since 2.3.0
+   */
+  def asNonNullabe(): UserDefinedFunction = {
+    if (!nullable) {
+      this
+    } else {
+      val udf = copyAll()
+      udf._nullable = false
+      udf
+    }
   }
 
   /**
-   * Updates UserDefinedFunction with a given nullability.
+   * Updates UserDefinedFunction to nondeterministic.
    *
    * @since 2.3.0
    */
-  def withNullability(nullable: Boolean): UserDefinedFunction = {
-    if (nullable == _nullable) {
+  def asNondeterministic(): UserDefinedFunction = {
+    if (!_deterministic) {
       this
     } else {
       val udf = copyAll()
-      udf._nullable = nullable
+      udf._deterministic = false
       udf
     }
   }