protected function ensureAlias(AbstractLoader $parent)
    {
        //Let's calculate loader alias
        if (empty($this->options['alias'])) {
            if ($this->isLoaded() && $this->isJoined()) {
                //Let's create unique alias, we are able to do that for relations just loaded
                $this->options['alias'] = 'd' . decoct(++self::$countLevels);
            } else {
                //Let's use parent alias to continue chain
                $this->options['alias'] = $parent->getAlias() . '_' . $this->relation;
            }
        }
    }