protected function getKvData(array $ids)
    {
        if (empty($ids)) {
            return [];
        }
        $result = [];
        $sql = 'SELECT * FROM ' . self::KV_TABLE_NAME . '
                WHERE ' . self::KV_COLUMN_PARENT_ID . ' IN(' . join(',', array_map(function(){ return '?'; }, $ids)) . ')';
        $secondaryData = $this->getPersistence()->query($sql, $ids)->fetchAll(\PDO::FETCH_ASSOC);

        foreach ($secondaryData as $data) {
            $result[$data[self::KV_COLUMN_PARENT_ID]][$data[self::KV_COLUMN_KEY]] = $data[self::KV_COLUMN_VALUE];
        }

        return $result;
    }