fix qualified name

Author: ulysses-you

sql/core/src/main/scala/org/apache/spark/sql/execution/command/functions.scala

@@ -251,7 +251,7 @@ case class RefreshFunctionCommand(
 
   override def run(sparkSession: SparkSession): Seq[Row] = {
     val catalog = sparkSession.sessionState.catalog
-    if (FunctionRegistry.builtin.functionExists(FunctionIdentifier(functionName))) {
+    if (FunctionRegistry.builtin.functionExists(FunctionIdentifier(functionName, databaseName))) {
       throw new AnalysisException(s"Cannot refresh built-in function $functionName")
     }
     if (catalog.isTemporaryFunction(FunctionIdentifier(functionName, databaseName))) {

sql/core/src/test/scala/org/apache/spark/sql/execution/command/DDLSuite.scala

@@ -3036,6 +3036,9 @@ abstract class DDLSuite extends QueryTest with SQLTestUtils {
       sql("REFRESH FUNCTION md5")
     }.getMessage
     assert(msg.contains("Cannot refresh built-in function"))
+    intercept[NoSuchFunctionException] {
+      sql("REFRESH FUNCTION default.md5")
+    }
 
     withUserDefinedFunction("func1" -> true) {
       sql("CREATE TEMPORARY FUNCTION func1 AS 'test.org.apache.spark.sql.MyDoubleAvg'")
@@ -3079,6 +3082,21 @@ abstract class DDLSuite extends QueryTest with SQLTestUtils {
       assert(!spark.sessionState.catalog.isRegisteredFunction(func))
     }
   }
+
+  test("REFRESH FUNCTION persistent function with the same name as the built-in function") {
+    withUserDefinedFunction("rand" -> false) {
+      val rand = FunctionIdentifier("rand", Some("default"))
+      sql("CREATE FUNCTION rand AS 'test.org.apache.spark.sql.MyDoubleAvg'")
+      assert(!spark.sessionState.catalog.isRegisteredFunction(rand))
+      val msg = intercept[AnalysisException] {
+        sql("REFRESH FUNCTION rand")
+      }.getMessage
+      assert(msg.contains("Cannot refresh built-in function"))
+      assert(!spark.sessionState.catalog.isRegisteredFunction(rand))
+      sql("REFRESH FUNCTION default.rand")
+      assert(spark.sessionState.catalog.isRegisteredFunction(rand))
+    }
+  }
 }
 
 object FakeLocalFsFileSystem {