MongoDB分片，添加新节点时如何重新平衡? [英] MongoDB sharding, how does it rebalance when adding new nodes?

问题描述

我试图了解MongoDB和分片的概念.如果我们从2个节点开始并对客户数据进行分区，则基于姓氏，其中A到M数据存储在节点1上，N到Z数据存储在节点2上. ?我只是看不到它将如何工作.

I'm trying to understand MongoDB and the concept of sharding. If we start with 2 nodes and partition say, customer data, based on last name where A thru M data is stored on node 1 and N thru Z data is stored on node 2. What happens when we want to scale out and add more nodes? I just don't see how that will work.

推荐答案

如果您有2个节点，并不意味着数据被分成2个大块.通过分区可以说是10个块，其中6个在服务器1上，其余在服务器2上.

If you have 2 nodes it doesn't mean that data is partitioned into 2 chunks. It can by partitioned to let's say 10 chunks and 6 of them are on server 1 ane rest is on server 2.

添加其他服务器时，MongoDB能够在新配置的节点之间重新分配这些块

When you add another server MongoDB is able to redistribute those chunks between nodes of new configuration

您可以在官方文档中阅读更多内容:

You can read more in official docs:

• http://www.mongodb.org/display/DOCS/Sharding+Introduction

http://www.mongodb.org/display/DOCS/Choosing+ a + Shard + Key

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