MongoDB复制集及数据分片详解（二）

数据分片

分片缘由

分片（sharding）是MongoDB用来将大型集合分割到不同服务器（集群）上所采用的方法。当单台服务器CPU，Memory，IO等无法满足需求，就需要将数据分片存放，减缓服务器压力。

分片架构

实验拓扑

配置过程

因为以上做过实验我们首先来清理一下数据

[root@node1 ~]# service mongod stop

Stopping mongod: [ OK ]

[root@node1 ~]# rm -rf /mongodb/data/*

#各节点都执行以上操作，若第一次做可忽略

Config Server配置

#安装所需包

[root@node2 mongodb]# ls

mongodb-org-server-2.6.10-1.x86_64.rpm mongodb-org-tools-2.6.10-1.x86_64.rpm

mongodb-org-shell-2.6.10-1.x86_64.rpm

[root@node2 mongodb]# yum install *.rpm -y

修改配置文件[root@node2 ~]# vim /etc//mongod.conf

logpath=/var/log/mongodb/mongod.log

logappend=true

fork=true

dbpath=/mongodb/data

configsvr=true #开启config server

pidfilepath=/var/run/mongodb/mongod.pid

#bind_ip=127.0.0.1

httpinterface=true

rest=true

创建数据目录

[root@node2 ~]# mkdir /mongodb/data -pv

mkdir: created directory `/mongodb'

mkdir: created directory `/mongodb/data'

[root@node2 ~]# chown -R mongod.mongod /mongodb

启动服务[root@node2 ~]# service mongod start

Starting mongod: [ OK ]

[root@node2 ~]# ss -tnl | grep 27019

LISTEN 0 128 *:27019 *:*

#监听端口已发生改变，不再是27017

Mongos配置

#安装所需包，Mongos节点只装此包即可，无需装第一次实验中的mongod的相关包

[root@node1 ~]# yum install mongodb-org-mongos-2.6.10-1.x86_64.rpm -y

启动服务

[root@node1 ~]# mongos --configdb=172.16.10.124 --fork --logpath=/var/log/mongodb/mongos.log

2015-07-13T22:22:47.404+0800 warning: running with 1 config server should be done only fo

r testing purposes and is not recommended for production

about to fork child process, waiting until server is ready for connections.

forked process: 3583

child process started successfully, parent exiting

#--configdb指定config server --logpath指定日志位置 --fork后台运行

Shard配置

#以为我们第一次实验安装过软件了，下面直接修改配置文件

[root@node3 ~]# vim /etc/mongod.conf

logpath=/var/log/mongodb/mongod.log

logappend=true

fork=true

dbpath=/mongodb/data

pidfilepath=/var/run/mongodb/mongod.pid

#bind_ip=127.0.0.1

httpinterface=true

rest=true

[root@node3 ~]# service mongod start

Starting mongod: [ OK ]

#两个shard节点都执行以上操作

Mongos节点添加Shard节点

[root@node1 ~]# mongo --host 172.16.10.123

MongoDB shell version: 2.6.10

connecting to: 172.16.10.123:27017/test

mongos> sh.addShard("172.16.10.125")

{ "shardAdded" : "shard0000", "ok" : 1 }

mongos> sh.addShard("172.16.10.126")

{ "shardAdded" : "shard0001", "ok" : 1 }

mongos> sh.status()

--- Sharding Status ---

sharding version: {

"_id" : 1,

"version" : 4,

"minCompatibleVersion" : 4,

"currentVersion" : 5,

"clusterId" : ObjectId("55a3c9ba131b83ff44e19435")

}

shards:

{ "_id" : "shard0000", "host" : "172.16.10.125:27017" }

{ "_id" : "shard0001", "host" : "172.16.10.126:27017" }

databases:

{ "_id" : "admin", "partitioned" : false, "primary" : "config" }

对所需对象启用分片功能

#对数据库启用sharding功能

mongos> sh.enableSharding("testdb")

{ "ok" : 1 }

mongos> sh.status()

--- Sharding Status ---

sharding version: {

"_id" : 1,

"version" : 4,

"minCompatibleVersion" : 4,

"currentVersion" : 5,

"clusterId" : ObjectId("55a3c9ba131b83ff44e19435")

}

shards:

{ "_id" : "shard0000", "host" : "172.16.10.125:27017" }

{ "_id" : "shard0001", "host" : "172.16.10.126:27017" }

databases:

{ "_id" : "admin", "partitioned" : false, "primary" : "config" }

{ "_id" : "test", "partitioned" : false, "primary" : "shard0000" }

{ "_id" : "testdb", "partitioned" : true, "primary" : "shard0000" }

#指定需要分片的Collection及索引

mongos> sh.shardCollection("testdb.students",{"age": 1})

{ "collectionsharded" : "testdb.students", "ok" : 1 }

mongos> sh.status()

--- Sharding Status ---

sharding version: {

"_id" : 1,

"version" : 4,

"minCompatibleVersion" : 4,

"currentVersion" : 5,

"clusterId" : ObjectId("55a3c9ba131b83ff44e19435")

}

shards:

{ "_id" : "shard0000", "host" : "172.16.10.125:27017" }

{ "_id" : "shard0001", "host" : "172.16.10.126:27017" }

databases:

{ "_id" : "admin", "partitioned" : false, "primary" : "config" }

{ "_id" : "test", "partitioned" : false, "primary" : "shard0000" }

{ "_id" : "testdb", "partitioned" : true, "primary" : "shard0000" }

testdb.students

shard key: { "age" : 1 }

chunks:

shard0000 1

{ "age" : { "$minKey" : 1 } } -->> { "age" : { "$maxKey" : 1 } }

on : shard0000 Timestamp(1, 0)

分片功能已开启，接下来我们手动创建数据来验证是否会分片

mongos> use testdb

switched to db testdb

mongos> for (i=1;i<=100000;i++) db.students.insert({name:"student"+i,age:(i%120),addr:"china"})

WriteResult({ "nInserted" : 1 })

mongos> db.students.find().count()

100000

mongos> sh.status()

--- Sharding Status ---

sharding version: {

"_id" : 1,

"version" : 4,

"minCompatibleVersion" : 4,

"currentVersion" : 5,

"clusterId" : ObjectId("55a3c9ba131b83ff44e19435")

}

shards:

{ "_id" : "shard0000", "host" : "172.16.10.125:27017" }

{ "_id" : "shard0001", "host" : "172.16.10.126:27017" }

databases:

{ "_id" : "admin", "partitioned" : false, "primary" : "config" }

{ "_id" : "test", "partitioned" : false, "primary" : "shard0000" }

{ "_id" : "testdb", "partitioned" : true, "primary" : "shard0000" }

testdb.students

shard key: { "age" : 1 }

chunks:

shard0001 1

shard0000 2

{ "age" : { "$minKey" : 1 } } -->> { "age" : 1 } on : shard0001 Timestamp(2, 0)

{ "age" : 1 } -->> { "age" : 119 } on : shard0000 Timestamp(2, 2)

{ "age" : 119 } -->> { "age" : { "$maxKey" : 1 } } on : shard0000 Timestamp(2, 3)

查看数据状态会发现数据已被分到不同shard上，至此，数据分片成功实现

The end

MongoDB复制集及数据分片就先说到这里了，通过以上简单应用可以看出，MongoDB在无论大数据处理还是复制方面都有着比MySQL更加优秀的性能和更加简单的操作，但由于MongoDB目前还不是很成熟，在实际的应用中还有许多问题有待解决，相信在未来MongoDB会更加出色。