https://blog.wongcw.com/2020/07/07/mysql-%e5%88%aa%e9%99%a4master%e3%80%81%e9%bb%91%e5%90%8d%e5%96%ae%e7%99%bd%e5%90%8d%e5%96%ae%e7%ad%89%e8%a1%93%e8%aa%9e/