Don't return row descriptions when executing SET queries

src/query_handler.go

@@ -340,7 +340,12 @@ func (queryHandler *QueryHandler) rowsToDescriptionMessages(rows *sql.Rows, quer
 	}
 
 	var messages []pgproto3.Message
-	messages = append(messages, queryHandler.generateRowDescription(cols))
+
+	rowDescription := queryHandler.generateRowDescription(cols)
+	if len(rowDescription.Fields) > 0 {
+		messages = append(messages, rowDescription)
+	}
+
 	return messages, nil
 }
 
@@ -383,6 +388,11 @@ func (queryHandler *QueryHandler) generateRowDescription(cols []*sql.ColumnType)
 	description := pgproto3.RowDescription{Fields: []pgproto3.FieldDescription{}}
 
 	for _, col := range cols {
+		if col.Name() == "Success" && col.ScanType().String() == "bool" && len(cols) == 1 {
+			// Skip the "Success" DuckDB column returned from SET ... commands
+			continue
+		}
+
 		description.Fields = append(description.Fields, pgproto3.FieldDescription{
 			Name:                 []byte(col.Name()),
 			TableOID:             0,

src/query_handler_test.go

@@ -137,11 +137,6 @@ func TestHandleQuery(t *testing.T) {
 			"description": {"table_catalog", "table_schema", "table"},
 			"values":      {"memory", "public", "test_table"},
 		},
-		// SET
-		"SET client_encoding TO 'UTF8'": {
-			"description": {"Success"},
-			"values":      {},
-		},
 		// Empty query
 		"-- ping": {
 			"description": {"1"},
@@ -658,6 +653,17 @@ func TestHandleQuery(t *testing.T) {
 			t.Errorf("Expected the error to be '"+expectedErrorMessage+"', got %v", err.Error())
 		}
 	})
+
+	t.Run("Returns a result without a row description for SET queries", func(t *testing.T) {
+		queryHandler := initQueryHandler()
+
+		messages, err := queryHandler.HandleQuery("SET client_encoding TO 'UTF8'")
+
+		testNoError(t, err)
+		testMessageTypes(t, messages, []pgproto3.Message{
+			&pgproto3.CommandComplete{},
+		})
+	})
 }
 
 func TestHandleParseQuery(t *testing.T) {
@@ -796,7 +802,6 @@ SET standard_conforming_strings = on;`
 
 		testNoError(t, err)
 		testMessageTypes(t, messages, []pgproto3.Message{
-			&pgproto3.RowDescription{},
 			&pgproto3.CommandComplete{},
 		})
 	})