1. CouchDB：
CouchDB是一个面向开源文档的NoSQL数据库，它使用多种格式和协议来存储，传输和处理其数据，它使用JSON来存储数据，使用JavaScript作为其使用MapReduce的查询语言以及用于API的HTTP。它由Apache Software Foundation开发，最初于2005年发布。它是用Erlang编写的。
2. IBM Db2：
IBM 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。
CouchDB和IBM Db2之间的区别：
| SR.NO | CouchDB | IBM Db2 |
|---|---|---|
| 1 | It is developed by Apache Software Foundation in 2005. | It is developed by IBM in 1983. |
| 2 | CouchDB server operating systems are Android, BSD, Linux, OS X, Solaris and Windows. | Db2 server operating systems are AIX, HP-UX, Linux, Solaris, Windows and z/OS. |
| 3 | The primary database model for CouchDB is Document Store. | The primary database model for IBM Db2 is Relational DBMS. |
| 4 | It is written in Erlang language. | It is written in C, C++, Assembly language, Java languages. |
| 5 | It is free of data schema. | It has fixed data schema. |
| 6 | It do not provides ACID transactions. | It provides ACID transactions. |
| 7 | It does not have the concept of Foreign keys. | It has the concept of Referential Integrity and Foreign keys. |
| 8 | It does not supports Secondary indexes. | It supports the secondary indexes without any restrictions. |