[SPARK-19338][SQL] Add UDF names in explain

## What changes were proposed in this pull request?
This pr added a variable for a UDF name in `ScalaUDF`.
Then, if the variable filled, `DataFrame#explain` prints the name.

## How was this patch tested?
Added a test in `UDFSuite`.

Author: Takeshi YAMAMURO <linguin.m.s@gmail.com>

Closes #16707 from maropu/SPARK-19338.

2 files changed, 38 insertions, 24 deletions

diff --git a/sql/core/src/main/scala/org/apache/spark/sql/UDFRegistration.scala b/sql/core/src/main/scala/org/apache/spark/sql/UDFRegistration.scala
index 14b1e87496..7abfa4ea37 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/UDFRegistration.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/UDFRegistration.scala
@@ -92,7 +92,7 @@ class UDFRegistration private[sql] (functionRegistry: FunctionRegistry) extends
         def register[$typeTags](name: String, func: Function$x[$types]): UserDefinedFunction = {
           val dataType = ScalaReflection.schemaFor[RT].dataType
           val inputTypes = Try($inputTypes).toOption
-          def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil))
+          def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil), Some(name))
           functionRegistry.registerFunction(name, builder)
           UserDefinedFunction(func, dataType, inputTypes)
         }""")
@@ -125,7 +125,7 @@ class UDFRegistration private[sql] (functionRegistry: FunctionRegistry) extends
   def register[RT: TypeTag](name: String, func: Function0[RT]): UserDefinedFunction = {
     val dataType = ScalaReflection.schemaFor[RT].dataType
     val inputTypes = Try(Nil).toOption
-    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil))
+    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil), Some(name))
     functionRegistry.registerFunction(name, builder)
     UserDefinedFunction(func, dataType, inputTypes)
   }
@@ -138,7 +138,7 @@ class UDFRegistration private[sql] (functionRegistry: FunctionRegistry) extends
   def register[RT: TypeTag, A1: TypeTag](name: String, func: Function1[A1, RT]): UserDefinedFunction = {
     val dataType = ScalaReflection.schemaFor[RT].dataType
     val inputTypes = Try(ScalaReflection.schemaFor[A1].dataType :: Nil).toOption
-    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil))
+    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil), Some(name))
     functionRegistry.registerFunction(name, builder)
     UserDefinedFunction(func, dataType, inputTypes)
   }
@@ -151,7 +151,7 @@ class UDFRegistration private[sql] (functionRegistry: FunctionRegistry) extends
   def register[RT: TypeTag, A1: TypeTag, A2: TypeTag](name: String, func: Function2[A1, A2, RT]): UserDefinedFunction = {
     val dataType = ScalaReflection.schemaFor[RT].dataType
     val inputTypes = Try(ScalaReflection.schemaFor[A1].dataType :: ScalaReflection.schemaFor[A2].dataType :: Nil).toOption
-    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil))
+    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil), Some(name))
     functionRegistry.registerFunction(name, builder)
     UserDefinedFunction(func, dataType, inputTypes)
   }
@@ -164,7 +164,7 @@ class UDFRegistration private[sql] (functionRegistry: FunctionRegistry) extends
   def register[RT: TypeTag, A1: TypeTag, A2: TypeTag, A3: TypeTag](name: String, func: Function3[A1, A2, A3, RT]): UserDefinedFunction = {
     val dataType = ScalaReflection.schemaFor[RT].dataType
     val inputTypes = Try(ScalaReflection.schemaFor[A1].dataType :: ScalaReflection.schemaFor[A2].dataType :: ScalaReflection.schemaFor[A3].dataType :: Nil).toOption
-    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil))
+    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil), Some(name))
     functionRegistry.registerFunction(name, builder)
     UserDefinedFunction(func, dataType, inputTypes)
   }
@@ -177,7 +177,7 @@ class UDFRegistration private[sql] (functionRegistry: FunctionRegistry) extends
   def register[RT: TypeTag, A1: TypeTag, A2: TypeTag, A3: TypeTag, A4: TypeTag](name: String, func: Function4[A1, A2, A3, A4, RT]): UserDefinedFunction = {
     val dataType = ScalaReflection.schemaFor[RT].dataType
     val inputTypes = Try(ScalaReflection.schemaFor[A1].dataType :: ScalaReflection.schemaFor[A2].dataType :: ScalaReflection.schemaFor[A3].dataType :: ScalaReflection.schemaFor[A4].dataType :: Nil).toOption
-    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil))
+    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil), Some(name))
     functionRegistry.registerFunction(name, builder)
     UserDefinedFunction(func, dataType, inputTypes)
   }
@@ -190,7 +190,7 @@ class UDFRegistration private[sql] (functionRegistry: FunctionRegistry) extends
   def register[RT: TypeTag, A1: TypeTag, A2: TypeTag, A3: TypeTag, A4: TypeTag, A5: TypeTag](name: String, func: Function5[A1, A2, A3, A4, A5, RT]): UserDefinedFunction = {
     val dataType = ScalaReflection.schemaFor[RT].dataType
     val inputTypes = Try(ScalaReflection.schemaFor[A1].dataType :: ScalaReflection.schemaFor[A2].dataType :: ScalaReflection.schemaFor[A3].dataType :: ScalaReflection.schemaFor[A4].dataType :: ScalaReflection.schemaFor[A5].dataType :: Nil).toOption
-    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil))
+    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil), Some(name))
     functionRegistry.registerFunction(name, builder)
     UserDefinedFunction(func, dataType, inputTypes)
   }
@@ -203,7 +203,7 @@ class UDFRegistration private[sql] (functionRegistry: FunctionRegistry) extends
   def register[RT: TypeTag, A1: TypeTag, A2: TypeTag, A3: TypeTag, A4: TypeTag, A5: TypeTag, A6: TypeTag](name: String, func: Function6[A1, A2, A3, A4, A5, A6, RT]): UserDefinedFunction = {
     val dataType = ScalaReflection.schemaFor[RT].dataType
     val inputTypes = Try(ScalaReflection.schemaFor[A1].dataType :: ScalaReflection.schemaFor[A2].dataType :: ScalaReflection.schemaFor[A3].dataType :: ScalaReflection.schemaFor[A4].dataType :: ScalaReflection.schemaFor[A5].dataType :: ScalaReflection.schemaFor[A6].dataType :: Nil).toOption
-    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil))
+    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil), Some(name))
     functionRegistry.registerFunction(name, builder)
     UserDefinedFunction(func, dataType, inputTypes)
   }
@@ -216,7 +216,7 @@ class UDFRegistration private[sql] (functionRegistry: FunctionRegistry) extends
   def register[RT: TypeTag, A1: TypeTag, A2: TypeTag, A3: TypeTag, A4: TypeTag, A5: TypeTag, A6: TypeTag, A7: TypeTag](name: String, func: Function7[A1, A2, A3, A4, A5, A6, A7, RT]): UserDefinedFunction = {
     val dataType = ScalaReflection.schemaFor[RT].dataType
     val inputTypes = Try(ScalaReflection.schemaFor[A1].dataType :: ScalaReflection.schemaFor[A2].dataType :: ScalaReflection.schemaFor[A3].dataType :: ScalaReflection.schemaFor[A4].dataType :: ScalaReflection.schemaFor[A5].dataType :: ScalaReflection.schemaFor[A6].dataType :: ScalaReflection.schemaFor[A7].dataType :: Nil).toOption
-    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil))
+    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil), Some(name))
     functionRegistry.registerFunction(name, builder)
     UserDefinedFunction(func, dataType, inputTypes)
   }
@@ -229,7 +229,7 @@ class UDFRegistration private[sql] (functionRegistry: FunctionRegistry) extends
   def register[RT: TypeTag, A1: TypeTag, A2: TypeTag, A3: TypeTag, A4: TypeTag, A5: TypeTag, A6: TypeTag, A7: TypeTag, A8: TypeTag](name: String, func: Function8[A1, A2, A3, A4, A5, A6, A7, A8, RT]): UserDefinedFunction = {
     val dataType = ScalaReflection.schemaFor[RT].dataType
     val inputTypes = Try(ScalaReflection.schemaFor[A1].dataType :: ScalaReflection.schemaFor[A2].dataType :: ScalaReflection.schemaFor[A3].dataType :: ScalaReflection.schemaFor[A4].dataType :: ScalaReflection.schemaFor[A5].dataType :: ScalaReflection.schemaFor[A6].dataType :: ScalaReflection.schemaFor[A7].dataType :: ScalaReflection.schemaFor[A8].dataType :: Nil).toOption
-    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil))
+    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil), Some(name))
     functionRegistry.registerFunction(name, builder)
     UserDefinedFunction(func, dataType, inputTypes)
   }
@@ -242,7 +242,7 @@ class UDFRegistration private[sql] (functionRegistry: FunctionRegistry) extends
   def register[RT: TypeTag, A1: TypeTag, A2: TypeTag, A3: TypeTag, A4: TypeTag, A5: TypeTag, A6: TypeTag, A7: TypeTag, A8: TypeTag, A9: TypeTag](name: String, func: Function9[A1, A2, A3, A4, A5, A6, A7, A8, A9, RT]): UserDefinedFunction = {
     val dataType = ScalaReflection.schemaFor[RT].dataType
     val inputTypes = Try(ScalaReflection.schemaFor[A1].dataType :: ScalaReflection.schemaFor[A2].dataType :: ScalaReflection.schemaFor[A3].dataType :: ScalaReflection.schemaFor[A4].dataType :: ScalaReflection.schemaFor[A5].dataType :: ScalaReflection.schemaFor[A6].dataType :: ScalaReflection.schemaFor[A7].dataType :: ScalaReflection.schemaFor[A8].dataType :: ScalaReflection.schemaFor[A9].dataType :: Nil).toOption
-    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil))
+    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil), Some(name))
     functionRegistry.registerFunction(name, builder)
     UserDefinedFunction(func, dataType, inputTypes)
   }
@@ -255,7 +255,7 @@ class UDFRegistration private[sql] (functionRegistry: FunctionRegistry) extends
   def register[RT: TypeTag, A1: TypeTag, A2: TypeTag, A3: TypeTag, A4: TypeTag, A5: TypeTag, A6: TypeTag, A7: TypeTag, A8: TypeTag, A9: TypeTag, A10: TypeTag](name: String, func: Function10[A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, RT]): UserDefinedFunction = {
     val dataType = ScalaReflection.schemaFor[RT].dataType
     val inputTypes = Try(ScalaReflection.schemaFor[A1].dataType :: ScalaReflection.schemaFor[A2].dataType :: ScalaReflection.schemaFor[A3].dataType :: ScalaReflection.schemaFor[A4].dataType :: ScalaReflection.schemaFor[A5].dataType :: ScalaReflection.schemaFor[A6].dataType :: ScalaReflection.schemaFor[A7].dataType :: ScalaReflection.schemaFor[A8].dataType :: ScalaReflection.schemaFor[A9].dataType :: ScalaReflection.schemaFor[A10].dataType :: Nil).toOption
-    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil))
+    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil), Some(name))
     functionRegistry.registerFunction(name, builder)
     UserDefinedFunction(func, dataType, inputTypes)
   }
@@ -268,7 +268,7 @@ class UDFRegistration private[sql] (functionRegistry: FunctionRegistry) extends
   def register[RT: TypeTag, A1: TypeTag, A2: TypeTag, A3: TypeTag, A4: TypeTag, A5: TypeTag, A6: TypeTag, A7: TypeTag, A8: TypeTag, A9: TypeTag, A10: TypeTag, A11: TypeTag](name: String, func: Function11[A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, A11, RT]): UserDefinedFunction = {
     val dataType = ScalaReflection.schemaFor[RT].dataType
     val inputTypes = Try(ScalaReflection.schemaFor[A1].dataType :: ScalaReflection.schemaFor[A2].dataType :: ScalaReflection.schemaFor[A3].dataType :: ScalaReflection.schemaFor[A4].dataType :: ScalaReflection.schemaFor[A5].dataType :: ScalaReflection.schemaFor[A6].dataType :: ScalaReflection.schemaFor[A7].dataType :: ScalaReflection.schemaFor[A8].dataType :: ScalaReflection.schemaFor[A9].dataType :: ScalaReflection.schemaFor[A10].dataType :: ScalaReflection.schemaFor[A11].dataType :: Nil).toOption
-    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil))
+    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil), Some(name))
     functionRegistry.registerFunction(name, builder)
     UserDefinedFunction(func, dataType, inputTypes)
   }
@@ -281,7 +281,7 @@ class UDFRegistration private[sql] (functionRegistry: FunctionRegistry) extends
   def register[RT: TypeTag, A1: TypeTag, A2: TypeTag, A3: TypeTag, A4: TypeTag, A5: TypeTag, A6: TypeTag, A7: TypeTag, A8: TypeTag, A9: TypeTag, A10: TypeTag, A11: TypeTag, A12: TypeTag](name: String, func: Function12[A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, A11, A12, RT]): UserDefinedFunction = {
     val dataType = ScalaReflection.schemaFor[RT].dataType
     val inputTypes = Try(ScalaReflection.schemaFor[A1].dataType :: ScalaReflection.schemaFor[A2].dataType :: ScalaReflection.schemaFor[A3].dataType :: ScalaReflection.schemaFor[A4].dataType :: ScalaReflection.schemaFor[A5].dataType :: ScalaReflection.schemaFor[A6].dataType :: ScalaReflection.schemaFor[A7].dataType :: ScalaReflection.schemaFor[A8].dataType :: ScalaReflection.schemaFor[A9].dataType :: ScalaReflection.schemaFor[A10].dataType :: ScalaReflection.schemaFor[A11].dataType :: ScalaReflection.schemaFor[A12].dataType :: Nil).toOption
-    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil))
+    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil), Some(name))
     functionRegistry.registerFunction(name, builder)
     UserDefinedFunction(func, dataType, inputTypes)
   }
@@ -294,7 +294,7 @@ class UDFRegistration private[sql] (functionRegistry: FunctionRegistry) extends
   def register[RT: TypeTag, A1: TypeTag, A2: TypeTag, A3: TypeTag, A4: TypeTag, A5: TypeTag, A6: TypeTag, A7: TypeTag, A8: TypeTag, A9: TypeTag, A10: TypeTag, A11: TypeTag, A12: TypeTag, A13: TypeTag](name: String, func: Function13[A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, A11, A12, A13, RT]): UserDefinedFunction = {
     val dataType = ScalaReflection.schemaFor[RT].dataType
     val inputTypes = Try(ScalaReflection.schemaFor[A1].dataType :: ScalaReflection.schemaFor[A2].dataType :: ScalaReflection.schemaFor[A3].dataType :: ScalaReflection.schemaFor[A4].dataType :: ScalaReflection.schemaFor[A5].dataType :: ScalaReflection.schemaFor[A6].dataType :: ScalaReflection.schemaFor[A7].dataType :: ScalaReflection.schemaFor[A8].dataType :: ScalaReflection.schemaFor[A9].dataType :: ScalaReflection.schemaFor[A10].dataType :: ScalaReflection.schemaFor[A11].dataType :: ScalaReflection.schemaFor[A12].dataType :: ScalaReflection.schemaFor[A13].dataType :: Nil).toOption
-    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil))
+    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil), Some(name))
     functionRegistry.registerFunction(name, builder)
     UserDefinedFunction(func, dataType, inputTypes)
   }
@@ -307,7 +307,7 @@ class UDFRegistration private[sql] (functionRegistry: FunctionRegistry) extends
   def register[RT: TypeTag, A1: TypeTag, A2: TypeTag, A3: TypeTag, A4: TypeTag, A5: TypeTag, A6: TypeTag, A7: TypeTag, A8: TypeTag, A9: TypeTag, A10: TypeTag, A11: TypeTag, A12: TypeTag, A13: TypeTag, A14: TypeTag](name: String, func: Function14[A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, A11, A12, A13, A14, RT]): UserDefinedFunction = {
     val dataType = ScalaReflection.schemaFor[RT].dataType
     val inputTypes = Try(ScalaReflection.schemaFor[A1].dataType :: ScalaReflection.schemaFor[A2].dataType :: ScalaReflection.schemaFor[A3].dataType :: ScalaReflection.schemaFor[A4].dataType :: ScalaReflection.schemaFor[A5].dataType :: ScalaReflection.schemaFor[A6].dataType :: ScalaReflection.schemaFor[A7].dataType :: ScalaReflection.schemaFor[A8].dataType :: ScalaReflection.schemaFor[A9].dataType :: ScalaReflection.schemaFor[A10].dataType :: ScalaReflection.schemaFor[A11].dataType :: ScalaReflection.schemaFor[A12].dataType :: ScalaReflection.schemaFor[A13].dataType :: ScalaReflection.schemaFor[A14].dataType :: Nil).toOption
-    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil))
+    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil), Some(name))
     functionRegistry.registerFunction(name, builder)
     UserDefinedFunction(func, dataType, inputTypes)
   }
@@ -320,7 +320,7 @@ class UDFRegistration private[sql] (functionRegistry: FunctionRegistry) extends
   def register[RT: TypeTag, A1: TypeTag, A2: TypeTag, A3: TypeTag, A4: TypeTag, A5: TypeTag, A6: TypeTag, A7: TypeTag, A8: TypeTag, A9: TypeTag, A10: TypeTag, A11: TypeTag, A12: TypeTag, A13: TypeTag, A14: TypeTag, A15: TypeTag](name: String, func: Function15[A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, A11, A12, A13, A14, A15, RT]): UserDefinedFunction = {
     val dataType = ScalaReflection.schemaFor[RT].dataType
     val inputTypes = Try(ScalaReflection.schemaFor[A1].dataType :: ScalaReflection.schemaFor[A2].dataType :: ScalaReflection.schemaFor[A3].dataType :: ScalaReflection.schemaFor[A4].dataType :: ScalaReflection.schemaFor[A5].dataType :: ScalaReflection.schemaFor[A6].dataType :: ScalaReflection.schemaFor[A7].dataType :: ScalaReflection.schemaFor[A8].dataType :: ScalaReflection.schemaFor[A9].dataType :: ScalaReflection.schemaFor[A10].dataType :: ScalaReflection.schemaFor[A11].dataType :: ScalaReflection.schemaFor[A12].dataType :: ScalaReflection.schemaFor[A13].dataType :: ScalaReflection.schemaFor[A14].dataType :: ScalaReflection.schemaFor[A15].dataType :: Nil).toOption
-    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil))
+    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil), Some(name))
     functionRegistry.registerFunction(name, builder)
     UserDefinedFunction(func, dataType, inputTypes)
   }
@@ -333,7 +333,7 @@ class UDFRegistration private[sql] (functionRegistry: FunctionRegistry) extends
   def register[RT: TypeTag, A1: TypeTag, A2: TypeTag, A3: TypeTag, A4: TypeTag, A5: TypeTag, A6: TypeTag, A7: TypeTag, A8: TypeTag, A9: TypeTag, A10: TypeTag, A11: TypeTag, A12: TypeTag, A13: TypeTag, A14: TypeTag, A15: TypeTag, A16: TypeTag](name: String, func: Function16[A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, A11, A12, A13, A14, A15, A16, RT]): UserDefinedFunction = {
     val dataType = ScalaReflection.schemaFor[RT].dataType
     val inputTypes = Try(ScalaReflection.schemaFor[A1].dataType :: ScalaReflection.schemaFor[A2].dataType :: ScalaReflection.schemaFor[A3].dataType :: ScalaReflection.schemaFor[A4].dataType :: ScalaReflection.schemaFor[A5].dataType :: ScalaReflection.schemaFor[A6].dataType :: ScalaReflection.schemaFor[A7].dataType :: ScalaReflection.schemaFor[A8].dataType :: ScalaReflection.schemaFor[A9].dataType :: ScalaReflection.schemaFor[A10].dataType :: ScalaReflection.schemaFor[A11].dataType :: ScalaReflection.schemaFor[A12].dataType :: ScalaReflection.schemaFor[A13].dataType :: ScalaReflection.schemaFor[A14].dataType :: ScalaReflection.schemaFor[A15].dataType :: ScalaReflection.schemaFor[A16].dataType :: Nil).toOption
-    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil))
+    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil), Some(name))
     functionRegistry.registerFunction(name, builder)
     UserDefinedFunction(func, dataType, inputTypes)
   }
@@ -346,7 +346,7 @@ class UDFRegistration private[sql] (functionRegistry: FunctionRegistry) extends
   def register[RT: TypeTag, A1: TypeTag, A2: TypeTag, A3: TypeTag, A4: TypeTag, A5: TypeTag, A6: TypeTag, A7: TypeTag, A8: TypeTag, A9: TypeTag, A10: TypeTag, A11: TypeTag, A12: TypeTag, A13: TypeTag, A14: TypeTag, A15: TypeTag, A16: TypeTag, A17: TypeTag](name: String, func: Function17[A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, A11, A12, A13, A14, A15, A16, A17, RT]): UserDefinedFunction = {
     val dataType = ScalaReflection.schemaFor[RT].dataType
     val inputTypes = Try(ScalaReflection.schemaFor[A1].dataType :: ScalaReflection.schemaFor[A2].dataType :: ScalaReflection.schemaFor[A3].dataType :: ScalaReflection.schemaFor[A4].dataType :: ScalaReflection.schemaFor[A5].dataType :: ScalaReflection.schemaFor[A6].dataType :: ScalaReflection.schemaFor[A7].dataType :: ScalaReflection.schemaFor[A8].dataType :: ScalaReflection.schemaFor[A9].dataType :: ScalaReflection.schemaFor[A10].dataType :: ScalaReflection.schemaFor[A11].dataType :: ScalaReflection.schemaFor[A12].dataType :: ScalaReflection.schemaFor[A13].dataType :: ScalaReflection.schemaFor[A14].dataType :: ScalaReflection.schemaFor[A15].dataType :: ScalaReflection.schemaFor[A16].dataType :: ScalaReflection.schemaFor[A17].dataType :: Nil).toOption
-    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil))
+    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil), Some(name))
     functionRegistry.registerFunction(name, builder)
     UserDefinedFunction(func, dataType, inputTypes)
   }
@@ -359,7 +359,7 @@ class UDFRegistration private[sql] (functionRegistry: FunctionRegistry) extends
   def register[RT: TypeTag, A1: TypeTag, A2: TypeTag, A3: TypeTag, A4: TypeTag, A5: TypeTag, A6: TypeTag, A7: TypeTag, A8: TypeTag, A9: TypeTag, A10: TypeTag, A11: TypeTag, A12: TypeTag, A13: TypeTag, A14: TypeTag, A15: TypeTag, A16: TypeTag, A17: TypeTag, A18: TypeTag](name: String, func: Function18[A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, A11, A12, A13, A14, A15, A16, A17, A18, RT]): UserDefinedFunction = {
     val dataType = ScalaReflection.schemaFor[RT].dataType
     val inputTypes = Try(ScalaReflection.schemaFor[A1].dataType :: ScalaReflection.schemaFor[A2].dataType :: ScalaReflection.schemaFor[A3].dataType :: ScalaReflection.schemaFor[A4].dataType :: ScalaReflection.schemaFor[A5].dataType :: ScalaReflection.schemaFor[A6].dataType :: ScalaReflection.schemaFor[A7].dataType :: ScalaReflection.schemaFor[A8].dataType :: ScalaReflection.schemaFor[A9].dataType :: ScalaReflection.schemaFor[A10].dataType :: ScalaReflection.schemaFor[A11].dataType :: ScalaReflection.schemaFor[A12].dataType :: ScalaReflection.schemaFor[A13].dataType :: ScalaReflection.schemaFor[A14].dataType :: ScalaReflection.schemaFor[A15].dataType :: ScalaReflection.schemaFor[A16].dataType :: ScalaReflection.schemaFor[A17].dataType :: ScalaReflection.schemaFor[A18].dataType :: Nil).toOption
-    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil))
+    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil), Some(name))
     functionRegistry.registerFunction(name, builder)
     UserDefinedFunction(func, dataType, inputTypes)
   }
@@ -372,7 +372,7 @@ class UDFRegistration private[sql] (functionRegistry: FunctionRegistry) extends
   def register[RT: TypeTag, A1: TypeTag, A2: TypeTag, A3: TypeTag, A4: TypeTag, A5: TypeTag, A6: TypeTag, A7: TypeTag, A8: TypeTag, A9: TypeTag, A10: TypeTag, A11: TypeTag, A12: TypeTag, A13: TypeTag, A14: TypeTag, A15: TypeTag, A16: TypeTag, A17: TypeTag, A18: TypeTag, A19: TypeTag](name: String, func: Function19[A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, A11, A12, A13, A14, A15, A16, A17, A18, A19, RT]): UserDefinedFunction = {
     val dataType = ScalaReflection.schemaFor[RT].dataType
     val inputTypes = Try(ScalaReflection.schemaFor[A1].dataType :: ScalaReflection.schemaFor[A2].dataType :: ScalaReflection.schemaFor[A3].dataType :: ScalaReflection.schemaFor[A4].dataType :: ScalaReflection.schemaFor[A5].dataType :: ScalaReflection.schemaFor[A6].dataType :: ScalaReflection.schemaFor[A7].dataType :: ScalaReflection.schemaFor[A8].dataType :: ScalaReflection.schemaFor[A9].dataType :: ScalaReflection.schemaFor[A10].dataType :: ScalaReflection.schemaFor[A11].dataType :: ScalaReflection.schemaFor[A12].dataType :: ScalaReflection.schemaFor[A13].dataType :: ScalaReflection.schemaFor[A14].dataType :: ScalaReflection.schemaFor[A15].dataType :: ScalaReflection.schemaFor[A16].dataType :: ScalaReflection.schemaFor[A17].dataType :: ScalaReflection.schemaFor[A18].dataType :: ScalaReflection.schemaFor[A19].dataType :: Nil).toOption
-    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil))
+    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil), Some(name))
     functionRegistry.registerFunction(name, builder)
     UserDefinedFunction(func, dataType, inputTypes)
   }
@@ -385,7 +385,7 @@ class UDFRegistration private[sql] (functionRegistry: FunctionRegistry) extends
   def register[RT: TypeTag, A1: TypeTag, A2: TypeTag, A3: TypeTag, A4: TypeTag, A5: TypeTag, A6: TypeTag, A7: TypeTag, A8: TypeTag, A9: TypeTag, A10: TypeTag, A11: TypeTag, A12: TypeTag, A13: TypeTag, A14: TypeTag, A15: TypeTag, A16: TypeTag, A17: TypeTag, A18: TypeTag, A19: TypeTag, A20: TypeTag](name: String, func: Function20[A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, A11, A12, A13, A14, A15, A16, A17, A18, A19, A20, RT]): UserDefinedFunction = {
     val dataType = ScalaReflection.schemaFor[RT].dataType
     val inputTypes = Try(ScalaReflection.schemaFor[A1].dataType :: ScalaReflection.schemaFor[A2].dataType :: ScalaReflection.schemaFor[A3].dataType :: ScalaReflection.schemaFor[A4].dataType :: ScalaReflection.schemaFor[A5].dataType :: ScalaReflection.schemaFor[A6].dataType :: ScalaReflection.schemaFor[A7].dataType :: ScalaReflection.schemaFor[A8].dataType :: ScalaReflection.schemaFor[A9].dataType :: ScalaReflection.schemaFor[A10].dataType :: ScalaReflection.schemaFor[A11].dataType :: ScalaReflection.schemaFor[A12].dataType :: ScalaReflection.schemaFor[A13].dataType :: ScalaReflection.schemaFor[A14].dataType :: ScalaReflection.schemaFor[A15].dataType :: ScalaReflection.schemaFor[A16].dataType :: ScalaReflection.schemaFor[A17].dataType :: ScalaReflection.schemaFor[A18].dataType :: ScalaReflection.schemaFor[A19].dataType :: ScalaReflection.schemaFor[A20].dataType :: Nil).toOption
-    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil))
+    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil), Some(name))
     functionRegistry.registerFunction(name, builder)
     UserDefinedFunction(func, dataType, inputTypes)
   }
@@ -398,7 +398,7 @@ class UDFRegistration private[sql] (functionRegistry: FunctionRegistry) extends
   def register[RT: TypeTag, A1: TypeTag, A2: TypeTag, A3: TypeTag, A4: TypeTag, A5: TypeTag, A6: TypeTag, A7: TypeTag, A8: TypeTag, A9: TypeTag, A10: TypeTag, A11: TypeTag, A12: TypeTag, A13: TypeTag, A14: TypeTag, A15: TypeTag, A16: TypeTag, A17: TypeTag, A18: TypeTag, A19: TypeTag, A20: TypeTag, A21: TypeTag](name: String, func: Function21[A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, A11, A12, A13, A14, A15, A16, A17, A18, A19, A20, A21, RT]): UserDefinedFunction = {
     val dataType = ScalaReflection.schemaFor[RT].dataType
     val inputTypes = Try(ScalaReflection.schemaFor[A1].dataType :: ScalaReflection.schemaFor[A2].dataType :: ScalaReflection.schemaFor[A3].dataType :: ScalaReflection.schemaFor[A4].dataType :: ScalaReflection.schemaFor[A5].dataType :: ScalaReflection.schemaFor[A6].dataType :: ScalaReflection.schemaFor[A7].dataType :: ScalaReflection.schemaFor[A8].dataType :: ScalaReflection.schemaFor[A9].dataType :: ScalaReflection.schemaFor[A10].dataType :: ScalaReflection.schemaFor[A11].dataType :: ScalaReflection.schemaFor[A12].dataType :: ScalaReflection.schemaFor[A13].dataType :: ScalaReflection.schemaFor[A14].dataType :: ScalaReflection.schemaFor[A15].dataType :: ScalaReflection.schemaFor[A16].dataType :: ScalaReflection.schemaFor[A17].dataType :: ScalaReflection.schemaFor[A18].dataType :: ScalaReflection.schemaFor[A19].dataType :: ScalaReflection.schemaFor[A20].dataType :: ScalaReflection.schemaFor[A21].dataType :: Nil).toOption
-    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil))
+    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil), Some(name))
     functionRegistry.registerFunction(name, builder)
     UserDefinedFunction(func, dataType, inputTypes)
   }
@@ -411,7 +411,7 @@ class UDFRegistration private[sql] (functionRegistry: FunctionRegistry) extends
   def register[RT: TypeTag, A1: TypeTag, A2: TypeTag, A3: TypeTag, A4: TypeTag, A5: TypeTag, A6: TypeTag, A7: TypeTag, A8: TypeTag, A9: TypeTag, A10: TypeTag, A11: TypeTag, A12: TypeTag, A13: TypeTag, A14: TypeTag, A15: TypeTag, A16: TypeTag, A17: TypeTag, A18: TypeTag, A19: TypeTag, A20: TypeTag, A21: TypeTag, A22: TypeTag](name: String, func: Function22[A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, A11, A12, A13, A14, A15, A16, A17, A18, A19, A20, A21, A22, RT]): UserDefinedFunction = {
     val dataType = ScalaReflection.schemaFor[RT].dataType
     val inputTypes = Try(ScalaReflection.schemaFor[A1].dataType :: ScalaReflection.schemaFor[A2].dataType :: ScalaReflection.schemaFor[A3].dataType :: ScalaReflection.schemaFor[A4].dataType :: ScalaReflection.schemaFor[A5].dataType :: ScalaReflection.schemaFor[A6].dataType :: ScalaReflection.schemaFor[A7].dataType :: ScalaReflection.schemaFor[A8].dataType :: ScalaReflection.schemaFor[A9].dataType :: ScalaReflection.schemaFor[A10].dataType :: ScalaReflection.schemaFor[A11].dataType :: ScalaReflection.schemaFor[A12].dataType :: ScalaReflection.schemaFor[A13].dataType :: ScalaReflection.schemaFor[A14].dataType :: ScalaReflection.schemaFor[A15].dataType :: ScalaReflection.schemaFor[A16].dataType :: ScalaReflection.schemaFor[A17].dataType :: ScalaReflection.schemaFor[A18].dataType :: ScalaReflection.schemaFor[A19].dataType :: ScalaReflection.schemaFor[A20].dataType :: ScalaReflection.schemaFor[A21].dataType :: ScalaReflection.schemaFor[A22].dataType :: Nil).toOption
-    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil))
+    def builder(e: Seq[Expression]) = ScalaUDF(func, dataType, e, inputTypes.getOrElse(Nil), Some(name))
     functionRegistry.registerFunction(name, builder)
     UserDefinedFunction(func, dataType, inputTypes)
   }
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/UDFSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/UDFSuite.scala
index e8ccefa69a..ae6b2bc375 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/UDFSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/UDFSuite.scala
@@ -17,6 +17,7 @@
 
 package org.apache.spark.sql
 
+import org.apache.spark.sql.execution.command.ExplainCommand
 import org.apache.spark.sql.test.SharedSQLContext
 import org.apache.spark.sql.test.SQLTestData._
 
@@ -248,4 +249,17 @@ class UDFSuite extends QueryTest with SharedSQLContext {
       sql("SELECT tmp.t.* FROM (SELECT testDataFunc(a, b) AS t from testData2) tmp").toDF(),
       testData2)
   }
+
+  test("SPARK-19338 Provide identical names for UDFs in the EXPLAIN output") {
+    def explainStr(df: DataFrame): String = {
+      val explain = ExplainCommand(df.queryExecution.logical, extended = false)
+      val sparkPlan = spark.sessionState.executePlan(explain).executedPlan
+      sparkPlan.executeCollect().map(_.getString(0).trim).headOption.getOrElse("")
+    }
+    val udf1 = "myUdf1"
+    val udf2 = "myUdf2"
+    spark.udf.register(udf1, (n: Int) => { n + 1 })
+    spark.udf.register(udf2, (n: Int) => { n * 1 })
+    assert(explainStr(sql("SELECT myUdf1(myUdf2(1))")).contains(s"UDF:$udf1(UDF:$udf2(1))"))
+  }
 }