November 2021
Intermediate to advanced
410 pages
12h 1m
Chinese
Content preview from MongoDB权威指南（第3版）
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173
第 9 章
应用程序设计
本章介绍如何设计应用程序以有效地与
MongoDB
协同工作，内容包括：
•
模式设计注意事项；
•
内嵌数据和引用数据之间的权衡；
•
优化技巧；
•
一致性注意事项；
•
模式迁移；
•
模式管理；
•
不适合使用
MongoDB
作为数据存储的场景。
9.1
模式设计注意事项
模式设计，即在文档中表示数据的方式，对于数据表示来说是非常关键的。最好的方式是
按照应用程序希望看到的形式来表示数据。因此，与关系数据库不同，在为模式进行建模
之前，首先需要了解查询和数据访问的方式。
以下是在设计模式时需要考虑的几个关键方面。
限制条件
有一些数据库或硬件的限制是你需要了解的。你还需要考虑
MongoDB
的一些特殊之
处，比如最大文档大小为
16MB
、从磁盘读写完整文档
、更新会重写整个文档，以及在
文档级别进行原子更新。
查询和写入的访问模式
你需要确定并量化应用程序和更大系统的工作负载。工作负载包括应用程序中的读操作
和写操作。一旦知道了查询的运行时间和频率，就可以识别最常见的查询。这些查询是
174
｜
第
9
章
在进行模式设计时需要支持的。一旦确定了这些查询，就应该尽量减少查询的数量，并
在设计中确保一起查询的数据存储在同一个文档中。
这些查询中未使用的数据应该存放在不同的集合中。不经常使用的数据也应该移动到 ...
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