fix

Author: ulysses-you

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/catalog/SessionCatalog.scala

@@ -1344,8 +1344,8 @@ class SessionCatalog(
   /**
    * Unregister a temporary or permanent function from a session-specific [[FunctionRegistry]]
    */
-  def unregisterFunction(name: FunctionIdentifier): Unit = {
-    if (!functionRegistry.dropFunction(name)) {
+  def unregisterFunction(name: FunctionIdentifier, ignoreIfNotExists: Boolean): Unit = {
+    if (!functionRegistry.dropFunction(name) && !ignoreIfNotExists) {
       throw new NoSuchFunctionException(
         formatDatabaseName(name.database.getOrElse(currentDb)), name.funcName)
     }

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

@@ -266,8 +266,9 @@ case class RefreshFunctionCommand(
       val func = catalog.getFunctionMetadata(identifier)
       catalog.registerFunction(func, true)
     } else {
-      // clear cached function.
-      catalog.unregisterFunction(identifier)
+      // clear cached function if exists.
+      catalog.unregisterFunction(identifier, true)
+      throw new NoSuchFunctionException(identifier.database.get, functionName)
     }
 
     Seq.empty[Row]

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

@@ -3058,7 +3058,9 @@ abstract class DDLSuite extends QueryTest with SQLTestUtils {
 
       spark.sessionState.catalog.externalCatalog.dropFunction("default", "func1")
       assert(spark.sessionState.catalog.isRegisteredFunction(func))
-      sql("REFRESH FUNCTION func1")
+      intercept[NoSuchFunctionException] {
+        sql("REFRESH FUNCTION func1")
+      }
       assert(!spark.sessionState.catalog.isRegisteredFunction(func))
 
       val function = CatalogFunction(func, "test.non.exists.udf", Seq.empty)