1.卡桑德拉(Cassandra)：
Cassandra是一个免费的开放源代码的分布式宽列存储NoSQL数据库管理系统。它由Apache Software Foundation开发，最初于2008年7月发布。Cassandra旨在处理许多商用服务器上的大量数据，提供高可用性而没有单点故障。
2. IBM Db2：
Db2是IBM开发的一系列数据管理产品，包括数据库服务器。它是一个关系数据库管理系统(RDBMS)，它通过XML支持面向对象的功能和非关系结构。 Db2旨在有效地存储，分析和检索数据。它最初于1983年发布，并用C，C++， Java和汇编语言编写。 Cassandra和IBM Db2之间的区别：
| S.NO. | Cassandra | IBM Db2 |
|---|---|---|
| 1. | It was developed by Apache Software Foundation and released in July 2008. | It was developed by IBM and initially released in 1983. |
| 2. | Cassandra is written only in Java language. | Db2 is written in C, C++, Assembly language, Java languages. |
| 3. | The primary database model for Cassandra is Wide Column Store. | The primary database model for Db2 is Relational DBMS. |
| 4. | Cassandra does not support XML data format. | Db2 supports XML data format. |
| 5. | Secondary indexes in Cassandra are restricted. | Db2 supports the secondary indexes without any restrictions. |
| 6. | Cassandra does not provide ACID transactions . | Db2 provides ACID transactions. |
| 7. | Cassandra is free of data schema. | In Db2 data schema is fixed. |
| 8. | Cassandra supports Map Reduce method. | Db2 does not support of Map Reduce method. |
| 9. | Cassandra does not have the concept of Foreign keys. | Db2 has the concept of Referential Integrity and Foreign keys. |
| 10. | Server operating systems for Cassandra are BSD, Linux, OS X, and Windows. | Server operating systems for Db2 are AIX, HP-UX, Linux, Solaris, Windows and z/OS. |
| 11. | Some companies like Hulu, Instagram, Intuit, Netflix, Reddit, etc use Cassandra. | Some companies like JPMorgan Chase, Bank of America, Scotiabank, Citi, etc use Db2. |