[SPARK-15108][SQL] Describe Permanent UDTF

#### What changes were proposed in this pull request?
When Describe a UDTF, the command returns a wrong result. The command is unable to find the function, which has been created and cataloged in the catalog but not in the functionRegistry.

This PR is to correct it. If the function is not in the functionRegistry, we will check the catalog for collecting the information of the UDTF function.

#### How was this patch tested?
Added test cases to verify the results

Author: gatorsmile <gatorsmile@gmail.com>

Closes #12885 from gatorsmile/showFunction.

2 files changed, 52 insertions, 4 deletions

diff --git a/sql/hive/src/main/scala/org/apache/spark/sql/hive/client/HiveClient.scala b/sql/hive/src/main/scala/org/apache/spark/sql/hive/client/HiveClient.scala
index b224664050..befdda1621 100644
--- a/sql/hive/src/main/scala/org/apache/spark/sql/hive/client/HiveClient.scala
+++ b/sql/hive/src/main/scala/org/apache/spark/sql/hive/client/HiveClient.scala
@@ -229,7 +229,7 @@ private[hive] trait HiveClient {
 
   /** Return an existing function in the database, assuming it exists. */
   final def getFunction(db: String, name: String): CatalogFunction = {
-    getFunctionOption(db, name).getOrElse(throw new NoSuchFunctionException(db, name))
+    getFunctionOption(db, name).getOrElse(throw new NoSuchPermanentFunctionException(db, name))
   }
 
   /** Return an existing function in the database, or None if it doesn't exist. */
diff --git a/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/SQLQuerySuite.scala b/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/SQLQuerySuite.scala
index f7da9e73f6..4845da7c85 100644
--- a/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/SQLQuerySuite.scala
+++ b/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/SQLQuerySuite.scala
@@ -29,7 +29,6 @@ import org.apache.spark.sql.execution.datasources.{HadoopFsRelation, LogicalRela
 import org.apache.spark.sql.functions._
 import org.apache.spark.sql.hive.{HiveUtils, MetastoreRelation}
 import org.apache.spark.sql.hive.test.TestHiveSingleton
-import org.apache.spark.sql.internal.SQLConf
 import org.apache.spark.sql.test.SQLTestUtils
 import org.apache.spark.sql.types._
 import org.apache.spark.unsafe.types.CalendarInterval
@@ -208,8 +207,7 @@ class SQLQuerySuite extends QueryTest with SQLTestUtils with TestHiveSingleton {
       Row("sha") :: Row("sha1") :: Row("sha2") :: Row("weekofyear") :: Nil)
   }
 
-  test("describe functions") {
-    // The Spark SQL built-in functions
+  test("describe functions - built-in functions") {
     checkKeywordsExist(sql("describe function extended upper"),
       "Function: upper",
       "Class: org.apache.spark.sql.catalyst.expressions.Upper",
@@ -253,6 +251,56 @@ class SQLQuerySuite extends QueryTest with SQLTestUtils with TestHiveSingleton {
         "When a = b, returns c; when a = d, return e; else return f")
   }
 
+  test("describe functions - user defined functions") {
+    withUserDefinedFunction("udtf_count" -> false) {
+      sql(
+        s"""
+           |CREATE FUNCTION udtf_count
+           |AS 'org.apache.spark.sql.hive.execution.GenericUDTFCount2'
+           |USING JAR '${hiveContext.getHiveFile("TestUDTF.jar").getCanonicalPath()}'
+        """.stripMargin)
+
+      checkKeywordsExist(sql("describe function udtf_count"),
+        "Function: default.udtf_count",
+        "Class: org.apache.spark.sql.hive.execution.GenericUDTFCount2",
+        "Usage: N/A")
+
+      checkAnswer(
+        sql("SELECT udtf_count(a) FROM (SELECT 1 AS a FROM src LIMIT 3) t"),
+        Row(3) :: Row(3) :: Nil)
+
+      checkKeywordsExist(sql("describe function udtf_count"),
+        "Function: default.udtf_count",
+        "Class: org.apache.spark.sql.hive.execution.GenericUDTFCount2",
+        "Usage: N/A")
+    }
+  }
+
+  test("describe functions - temporary user defined functions") {
+    withUserDefinedFunction("udtf_count_temp" -> true) {
+      sql(
+        s"""
+           |CREATE TEMPORARY FUNCTION udtf_count_temp
+           |AS 'org.apache.spark.sql.hive.execution.GenericUDTFCount2'
+           |USING JAR '${hiveContext.getHiveFile("TestUDTF.jar").getCanonicalPath()}'
+        """.stripMargin)
+
+      checkKeywordsExist(sql("describe function udtf_count_temp"),
+        "Function: udtf_count_temp",
+        "Class: org.apache.spark.sql.hive.execution.GenericUDTFCount2",
+        "Usage: N/A")
+
+      checkAnswer(
+        sql("SELECT udtf_count_temp(a) FROM (SELECT 1 AS a FROM src LIMIT 3) t"),
+        Row(3) :: Row(3) :: Nil)
+
+      checkKeywordsExist(sql("describe function udtf_count_temp"),
+        "Function: udtf_count_temp",
+        "Class: org.apache.spark.sql.hive.execution.GenericUDTFCount2",
+        "Usage: N/A")
+    }
+  }
+
   test("SPARK-5371: union with null and sum") {
     val df = Seq((1, 1)).toDF("c1", "c2")
     df.registerTempTable("table1")