[SPARK-14888][SQL] UnresolvedFunction should use FunctionIdentifier

## What changes were proposed in this pull request?
This patch changes UnresolvedFunction and UnresolvedGenerator to use a FunctionIdentifier rather than just a String for function name. Also changed SessionCatalog to accept FunctionIdentifier in lookupFunction.

## How was this patch tested?
Updated related unit tests.

Author: Reynold Xin <rxin@databricks.com>

Closes #12659 from rxin/SPARK-14888.

2 files changed, 7 insertions, 9 deletions

diff --git a/sql/hive/compatibility/src/test/scala/org/apache/spark/sql/hive/execution/HiveCompatibilitySuite.scala b/sql/hive/compatibility/src/test/scala/org/apache/spark/sql/hive/execution/HiveCompatibilitySuite.scala
index 3e97edb67e..01b24d2f7e 100644
--- a/sql/hive/compatibility/src/test/scala/org/apache/spark/sql/hive/execution/HiveCompatibilitySuite.scala
+++ b/sql/hive/compatibility/src/test/scala/org/apache/spark/sql/hive/execution/HiveCompatibilitySuite.scala
@@ -74,7 +74,7 @@ class HiveCompatibilitySuite extends HiveQueryFileTest with BeforeAndAfter {
       TestHive.setConf(HiveUtils.CONVERT_METASTORE_ORC, originalConvertMetastoreOrc)
       TestHive.sessionState.functionRegistry.restore()
 
-      // For debugging dump some statistics about how much time was spent in various optimizer rules.
+      // For debugging dump some statistics about how much time was spent in various optimizer rules
       logWarning(RuleExecutor.dumpTimeSpent())
     } finally {
       super.afterAll()
diff --git a/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveSessionCatalog.scala b/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveSessionCatalog.scala
index 3e718826fe..9e527073d4 100644
--- a/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveSessionCatalog.scala
+++ b/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveSessionCatalog.scala
@@ -27,18 +27,16 @@ import org.apache.hadoop.hive.ql.exec.{FunctionRegistry => HiveFunctionRegistry}
 import org.apache.hadoop.hive.ql.udf.generic.{AbstractGenericUDAFResolver, GenericUDF, GenericUDTF}
 
 import org.apache.spark.sql.{AnalysisException, SQLContext}
-import org.apache.spark.sql.catalyst.TableIdentifier
+import org.apache.spark.sql.catalyst.{FunctionIdentifier, TableIdentifier}
 import org.apache.spark.sql.catalyst.analysis.FunctionRegistry
 import org.apache.spark.sql.catalyst.analysis.FunctionRegistry.FunctionBuilder
 import org.apache.spark.sql.catalyst.catalog.{FunctionResourceLoader, SessionCatalog}
 import org.apache.spark.sql.catalyst.expressions.{Expression, ExpressionInfo}
 import org.apache.spark.sql.catalyst.plans.logical.{LogicalPlan, SubqueryAlias}
 import org.apache.spark.sql.catalyst.rules.Rule
-import org.apache.spark.sql.execution.datasources.BucketSpec
 import org.apache.spark.sql.hive.HiveShim.HiveFunctionWrapper
 import org.apache.spark.sql.hive.client.HiveClient
 import org.apache.spark.sql.internal.SQLConf
-import org.apache.spark.sql.types.StructType
 import org.apache.spark.util.Utils
 
 
@@ -176,7 +174,7 @@ private[sql] class HiveSessionCatalog(
   // regexp, sentences, stack, std, str_to_map, windowingtablefunction, xpath, xpath_boolean,
   // xpath_double, xpath_float, xpath_int, xpath_long, xpath_number,
   // xpath_short, and xpath_string.
-  override def lookupFunction(name: String, children: Seq[Expression]): Expression = {
+  override def lookupFunction(name: FunctionIdentifier, children: Seq[Expression]): Expression = {
     // TODO: Once lookupFunction accepts a FunctionIdentifier, we should refactor this method to
     // if (super.functionExists(name)) {
     //   super.lookupFunction(name, children)
@@ -187,7 +185,7 @@ private[sql] class HiveSessionCatalog(
     Try(super.lookupFunction(name, children)) match {
       case Success(expr) => expr
       case Failure(error) =>
-        if (functionRegistry.functionExists(name)) {
+        if (functionRegistry.functionExists(name.unquotedString)) {
           // If the function actually exists in functionRegistry, it means that there is an
           // error when we create the Expression using the given children.
           // We need to throw the original exception.
@@ -196,7 +194,7 @@ private[sql] class HiveSessionCatalog(
           // This function is not in functionRegistry, let's try to load it as a Hive's
           // built-in function.
           // Hive is case insensitive.
-          val functionName = name.toLowerCase
+          val functionName = name.unquotedString.toLowerCase
           // TODO: This may not really work for current_user because current_user is not evaluated
           // with session info.
           // We do not need to use executionHive at here because we only load
@@ -204,12 +202,12 @@ private[sql] class HiveSessionCatalog(
           val functionInfo = {
             try {
               Option(HiveFunctionRegistry.getFunctionInfo(functionName)).getOrElse(
-                failFunctionLookup(name))
+                failFunctionLookup(name.unquotedString))
             } catch {
               // If HiveFunctionRegistry.getFunctionInfo throws an exception,
               // we are failing to load a Hive builtin function, which means that
               // the given function is not a Hive builtin function.
-              case NonFatal(e) => failFunctionLookup(name)
+              case NonFatal(e) => failFunctionLookup(name.unquotedString)
             }
           }
           val className = functionInfo.getFunctionClass.getName