has many fetch with join

test/orm/backend/test_result_reader.cpp

@@ -18,6 +18,8 @@ size_t test_result_reader::start_column_index() const {
   return 0;
 }
 
+void test_result_reader::unshift() {}
+
 void test_result_reader::read_value(const char *id, const size_t index, int8_t &value) {
   value = -8;
 }