[spark] Fix load function with SparkGenericCatalog

paimon-spark/paimon-spark-common/src/main/java/org/apache/paimon/spark/catalog/SupportFunction.java

@@ -27,8 +27,6 @@
 import org.apache.spark.sql.connector.catalog.SupportsNamespaces;
 import org.apache.spark.sql.connector.catalog.functions.UnboundFunction;
 
-import java.util.Arrays;
-
 import static org.apache.paimon.catalog.Catalog.SYSTEM_DATABASE_NAME;
 
 /** Catalog methods for working with Functions. */
@@ -54,7 +52,7 @@ default Identifier[] listFunctions(String[] namespace) throws NoSuchNamespaceExc
             return new Identifier[0];
         }
 
-        throw new RuntimeException("Namespace " + Arrays.toString(namespace) + " is not valid");
+        throw new NoSuchNamespaceException(namespace);
     }
 
     @Override
@@ -66,6 +64,6 @@ default UnboundFunction loadFunction(Identifier ident) throws NoSuchFunctionExce
             }
         }
 
-        throw new RuntimeException("Function " + ident + " is not a paimon function");
+        throw new NoSuchFunctionException(ident);
     }
 }

paimon-spark/paimon-spark-ut/src/test/scala/org/apache/paimon/spark/sql/PaimonFunctionTest.scala

@@ -23,6 +23,8 @@ import org.apache.paimon.spark.catalog.functions.PaimonFunctions
 
 import org.apache.spark.sql.Row
 import org.apache.spark.sql.connector.catalog.{FunctionCatalog, Identifier}
+import org.apache.spark.sql.expressions.{MutableAggregationBuffer, UserDefinedAggregateFunction}
+import org.apache.spark.sql.types.{DataType, IntegerType, StructType}
 
 class PaimonFunctionTest extends PaimonHiveTestBase {
 
@@ -85,4 +87,49 @@ class PaimonFunctionTest extends PaimonHiveTestBase {
       )
     }
   }
+
+  test("Paimon function: show and load function with SparkGenericCatalog") {
+    sql(s"USE $sparkCatalogName")
+    sql(s"USE $hiveDbName")
+    sql("CREATE FUNCTION myIntSum AS 'org.apache.paimon.spark.sql.MyIntSum'")
+    checkAnswer(
+      sql(s"SHOW FUNCTIONS FROM $hiveDbName LIKE 'myIntSum'"),
+      Row("spark_catalog.test_hive.myintsum"))
+
+    withTable("t") {
+      sql("CREATE TABLE t (id INT)")
+      sql("INSERT INTO t VALUES (1), (2), (3)")
+      checkAnswer(sql("SELECT myIntSum(id) FROM t"), Row(6))
+    }
+
+    sql("DROP FUNCTION myIntSum")
+    checkAnswer(sql(s"SHOW FUNCTIONS FROM $hiveDbName LIKE 'myIntSum'"), Seq.empty)
+  }
+}
+
+private class MyIntSum extends UserDefinedAggregateFunction {
+
+  override def inputSchema: StructType = new StructType().add("input", IntegerType)
+
+  override def bufferSchema: StructType = new StructType().add("buffer", IntegerType)
+
+  override def dataType: DataType = IntegerType
+
+  override def deterministic: Boolean = true
+
+  override def initialize(buffer: MutableAggregationBuffer): Unit = {
+    buffer.update(0, 0)
+  }
+
+  override def update(buffer: MutableAggregationBuffer, input: Row): Unit = {
+    buffer.update(0, buffer.getInt(0) + input.getInt(0))
+  }
+
+  override def merge(buffer1: MutableAggregationBuffer, buffer2: Row): Unit = {
+    buffer1.update(0, buffer1.getInt(0) + buffer2.getInt(0))
+  }
+
+  override def evaluate(buffer: Row): Any = {
+    buffer.getInt(0)
+  }
 }