MongoDB学习笔记

这是我阅读《MongoDB权威指南》的学习笔记，前七章侧重在开发者角度谈MongoDB,后面才是运维管理者角度

一. 理论部分

入门

文档：多个键及其关联的值有序地放置在一起便是文档
集合：一组文档

虽然子集合没有特别的地方，但还是很有用，很多MongoDB工具中都包含子集合

GridFS是一种存储大文件的协议，使用子集合来存储文件的元数据，这样就与内容块分开了
MongoDB的Web控制台通过子集合的方式将数据组织在DBTOP部分
绝大多数驱动程序都提供语法糖，为访问指定集合的子集合提供方便。例如：在数据库shell里面，db.blog代表blog集合，db.blog.posts代表blog.posts集合

在MongoDB中使用子集合来组织数据是很好的方法，在此强烈推荐

数据类型

JSON表现力也有限制，因为只有null,布尔，数字，字符串，数组和对象几种类型，
MongoDB保留JSON键值对基础上，增添了其他一些数据类型

使用GridFS存储文件有如下原因：

会直接利用业已建立的复制或分片机制，所以对于文件存储来说故障恢复和扩展都很容易
可以避免用户上传内容的文件系统出现的某些问题
不产生磁盘碎片，因为MongoDB分配数据文件空间以2GB为一块

开发者角度到此为止，下一篇是运维角度的学习

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