November 2020
Beginner to intermediate
214 pages
5h 10m
Chinese
Content preview from 数据库可靠性工程：数据库系统设计与运维指南
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数据存储领域指南
｜
167
档结构的元数据，允许进行数据类型优化、辅助索引以及其他优化。文档存储将与对象相
关的所有信息存储在一起，而不是跨表存储。这样一次调用便能获取所有数据，
而无须表
连接（声称简单，实际会消耗大量资源）。通常也不需要
ORM
层。
另外，这意味着如果对象需要不同的视图，那么文档存储必然不需要范式，这会导致膨胀
和一致性问题。此外，由于没有
schema
这样的简明文档，因此需要使用外部工具来实施
数据治理
4
。
数据治理
数据治理是对组织数据的可用性、完整性和安全性的管理。应该仔细考虑并
记录新添加的数据属性。在数据存储中使用
JSON
，会很容易甚至意外添加
新的数据属性。
4.
导航模型
导航模型始于分层和网络数据库。如今提到导航模型，几乎总是指图数据模型。图数据库
使用节点、边和属性来表示存储的数据以及对象之间的连接。节点包含特定对象的数据，
边是对象之间的关系，属性可添加节点相关数据。因为关系是作为数据的一部分直接存储
的，所以易于追踪连接。通常可以在一次调用中检索整个图。
与文档存储一样，图存储通常能直接映射到面向对象应用程序的结构中，同时消除了表连
接，并且在数据模型演化方面更灵活。当然，这只适用于查询图的数据。实践证明传统查
询模式的性能可能差得多
5
。
每种模型都有适用场景。下面讨论其中的选择和权衡。首先看看事务和属性。
11.1.2
事务
数据存储如何处理事务，也是需要考虑和理解的重要属性。事务实际上是数据库的逻辑工
作单元，可以认为不可分割。事务中的所有操作必须全部执行或回滚，以保持数据存储的 ...
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.