1. 沙发数据库：
Apache CouchDB 是一个开源的面向文档的 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 存储数据，使用 MapReduce 作为其查询语言的 JavaScript，以及用于 API 的 HTTP。它由 Apache 软件基金会开发，最初于 2005 年发布。它是用 Erlang 编写的。
2. 关系数据库：
RDBMS 代表关系数据库管理系统。它是最受欢迎的数据库。其中，数据以行的形式存储，即元组的形式。它包含许多表，数据可以很容易地访问，因为数据存储在表中。该模型由 EF Codd 提出。
CouchDB 和关系型数据库的区别：
| CouchDB | Relational Database |
|---|---|
| It is developed by Apache Software Foundation and initially released in 2005. | It is developed by Oracle on May 1995. |
| It is written in Erlang language. | It is developed in C and C++ languages. |
| The primary database model for CouchDB is Document Store. | The primary database model for relational database is client/server model. |
| It can handle only one connection at a time. | It can handle multiple connections simultaneously. |
| It does support XML data format. | It does not supports XML data format. |
| In CouchDB, there is no predefined datatypes. | It supports predefined datatypes such as float, date, number, etc. |
| It does not support Secondary indexes. | It supports Secondary indexes. |
| It does not support ACID transactions. | It provides ACID transactions. |
| It supports Map Reduce method. | It does not support Map Reduce method. |
| It has no Data Schema. | It has Data Schema. |