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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216
第 12章
从应用程序连接副本集
本章介绍如何在应用程序中与副本集进行交互，包括：
•
如何连接到副本集以及故障转移的工作机制；
•
在进行写操作时等待复制；
•
将读请求路由到正确的成员。
12.1
客户端到副本集的连接行为
MongoDB
的客户端开发库（也叫“驱动程序”）用于管理与
MongoDB
服务器端的通信，
无论服务器端是单机的
MongoDB
实例还是副本集
。对于副本集，默认情况下，驱动程序
会连接到主节点，并将所有流量都路由到此节点。应用程序可以像与单机服务器通信一样
执行读写操作，同时副本集会在后台悄悄地处理热备份。
连接副本集与连接单机服务器非常类似。在驱动程序中使用
MongoClient
类（或等价类），
并提供一个种子列表供驱动程序连接。种子列表就是服务器地址列表。
种子
是应用程序将
读取和写入数据的副本集成员。你不需要列出种子列表中的所有成员（尽管这样做也可
以）。当驱动程序连接到种子服务器时，它可以从其中发现其他成员。一个连接字符串通
常看起来像下面这样：
"mongodb://server-1:27017,server-2:27017,server-3:27017"
详情请参阅相关的驱动程序文档。
如果想提供更强的容错能力，那么也可以使用
DNS
种
子列表连接格式来指定应用程序连
接到副本集的方式。使用
DNS
的优点
是可以轮流更改
MongoDB
副本集成员所在的服务
器，而无须重新配置客户端（特指连接字符串）。
从应用程序连接副本集
｜
217
所有
MongoDB
驱动程序都遵守服务器发现和监控（
SDAM ...
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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.