November 2021
Intermediate to advanced
410 pages
12h 1m
Chinese
Content preview from MongoDB权威指南（第3版）
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.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.I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.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.
294
｜
第
17
章
分片，那么当所有块从分片上迁移出去时，就会得到这个回复信息。
一旦分片开始排空数据，就没有内置的方法可以停止此过程了。
17.4
数据均衡
通常来说，
MongoDB
会自动处理数据均衡。本节介绍如何启用和禁用自动均衡，以及如
何干预均衡的过程。
17.4.1
均衡器
关闭均衡器是大部分管理操作的先决条件。有一个
shell
辅助函数可以简单实现这一过程：
> sh.setBalancerState(false)
{
"ok" : 1,
"operationTime" : Timestamp(1541450923, 2),
"$clusterTime" : {
"clusterTime" : Timestamp(1541450923, 2),
"signature" : {
"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
"keyId" : NumberLong(0)
}
}
}
随着均衡器被关闭，新的均衡流程将不会再开始，但是关闭均衡器不会迫使正在进行的均
衡过程立即停止，也就是说，迁移过程通常不能立即停止。因此，应该检查
config.locks
集
合以查看是否仍有均衡过程正在进行：
> db.locks.find({"_id" : "balancer"})["state"]
0
0
表示均衡器已关闭。
均衡过程会增加系统的负载：目标分片必须查询源分片块中的所有文档，将文档插入目
标分片的块中，然后源分片必须删除这些文档 ...
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access
More than 5,000 organizations count on O’Reilly
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
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.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
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.