1. Amazon Aurora：
它是来自Amazon Web Services的完全托管的关系数据库引擎，与PostgreSQL和MySQL兼容。它比标准MySQL数据库快五倍，比标准PostgreSQL数据库快三倍。 Aurora的功能是分布式，容错和自我修复的存储系统。
2.第四维度(4D)：
第四维是关系数据库管理系统和由LaurentRibardière开发的IDE。 4D可以作为服务器运行，以便多个客户端可以管理一个数据库。 4D创建于1984年，并于1987年在Macintosh上稍有延迟地公开发布。它是一个具有集成数据库管理系统的应用程序开发环境。
Amazon Aurora和4D之间的区别：
| AMAZON AURORA | 4D |
|---|---|
| It is developed by Amazon in 2015. | It is developed By 4D, Inc in 1984. |
| It is a MySQL and PostgreSQL compatible cloud service by Amazon. | It is a hosted simple database service by Amazon, with the data stored in the Amazon Cloud. |
| It supports predefined data types such as float or date. | It does not support predefined data types such as float or date. |
| Immediate Consistency is used to ensure consistency in a distributed system. | Eventual Consistency and Immediate Consistency is used to ensure consistency in a distributed system. |
| It is available as a cloud service. | It is not available as a cloud service. |
| The partitioning can be done with horizontal partitioning. | There is no Partitioning method. |
| It supports SQL query language. | It does not support the SQL query language. |
| It provides the concept of Referential Integrity. Hence, no Foreign Keys. | It does not provide the concept of Referential Integrity. Hence, no Foreign Keys. |
| APIs and other access methods supported are ODBC, RESTful HTTP API and SOAP web-services. | APIs and other access methods supported are JDBC and ODBC. |