https://genesis-aka.net/language/japanese/2021/02/01/ntt%e8%a5%bf%e6%97%a5%e6%9c%ac%e3%80%81%e5%9c%b0%e5%9f%9f%e4%bc%81%e6%a5%ad%e5%90%91%e3%81%91%e3%82%af%e3%83%a9%e3%82%a6%e3%83%89%e3%81%aedb%e5%9f%ba%e7%9b%a4%e3%81%ab%e3%80%8coracle-exadata-cloudcus/