MongoDB之分片
1、环境
操作系统信息：
服务器规划：
从上表可以看到有四个组件：mongos、config server、shard、replica set。
mongos：数据库集群请求的入口，所有的请求都通过mongos进行协调，不需要在应用程序添加一个路由选择器，mongos自己就是一个请求分发中心，它负责把对应的数据请求转发到对应的shard服务器上。在生产环境通常有多mongos作为请求的入口，防止其中一个挂掉所有的mongodb请求都没有办法操作。
config server：顾名思义为配置服务器，存储所有数据库元信息（路由、分片）的配置。mongos本身没有物理存储分片服务器和数据路由信息，只是缓存在内存里，配置服务器则实际存储这些数据。mongos第一次启动或者关掉重启就会从 config server 加载配置信息，以后如果配置服务器信息变化会通知到所有的 mongos 更新自己的状态，这样 mongos 就能继续准确路由。在生产环境通常有多个 config server 配置服务器（必须配置为１个或者３个），因为它存储了分片路由的元数据，防止数据丢失！
shard：分片（sharding）是指将数据库拆分，将其分散在不同的机器上的过程。将数据分散到不同的机器上，不需要功能强大的服务器就可以存储更多的数据和处理更大的负载。基本思想就是将集合切成小块，这些块分散到若干片里，每个片只负责总数据的一部分，最后通过一个均衡器来对各个分片进行均衡（数据迁移）。
replica set：中文翻译副本集，其实就是shard的备份，防止shard挂掉之后数据丢失。复制提供了数据的冗余备份，并在多个服务器上存储数据副本，提高了数据的可用性， 并可以保证数据的安全性。
仲裁者（Arbiter）：是复制集中的一个MongoDB实例，它并不保存数据。仲裁节点使用最小的资源，不能将Arbiter部署在同一个数据集节点中，可以部署在其他应用服务器或者监视服务器中，也可部署在单独的虚拟机中。为了确保复制集中有奇数的投票成员（包括primary），需要添加仲裁节点做为投票，否则primary不能运行时不会自动切换primary。
简单了解之后，可以这样总结一下，应用请求mongos来操作mongodb的增删改查，配置服务器存储数据库元信息，并且和mongos做同步，数据最终存入在shard（分片）上，为了防止数据丢失同步在副本集中存储了一份，仲裁在数据存储到分片的时候决定存储到哪个节点。
总共规划了mongos 3个， config server 3个，数据分3片 shard server 3个，每个shard 有一个副本一个仲裁也就是 3 * 2 = 6 个，总共需要部署15个实例。这些实例可以部署在独立机器也可以部署在一台机器，我们这里测试资源有限，只准备了 3台机器，在同一台机器只要端口不同就可以了。
2、安装mongodb
分别在3台机器上面安装mongodb
[root@D2-POMS15 ~]# tar -xvzf mongodb-linux-x86_64-rhel62-3.4.7.tgz -C /usr/local/
[root@D2-POMS15 ~]# mv /usr/local/mongodb-linux-x86_64-rhel62-3.4.7/ /usr/local/mongodb
配置环境变量
[root@D2-POMS15 ~]# vim .bash_profile
export PATH=$PATH:/usr/local/mongodb/bin/
[root@D2-POMS15 ~]# source .bash_profile
分别在每台机器建立conf、mongos、config、shard1、shard2、shard3六个目录，因为mongos不存储数据，只需要建立日志文件目录即可。
[root@D2-POMS15 ~]# mkdir -p /usr/local/mongodb/conf
[root@D2-POMS15 ~]# mkdir -p /usr/local/mongodb/mongos/log
[root@D2-POMS15 ~]# mkdir -p /usr/local/mongodb/config/data
[root@D2-POMS15 ~]# mkdir -p /usr/local/mongodb/config/log
[root@D2-POMS15 ~]# mkdir -p /usr/local/mongodb/shard1/data
[root@D2-POMS15 ~]# mkdir -p /usr/local/mongodb/shard1/log
[root@D2-POMS15 ~]# mkdir -p /usr/local/mongodb/shard2/data
[root@D2-POMS15 ~]# mkdir -p /usr/local/mongodb/shard2/log
[root@D2-POMS15 ~]# mkdir -p /usr/local/mongodb/shard3/data
[root@D2-POMS15 ~]# mkdir -p /usr/local/mongodb/shard3/log
3、config server配置服务器
mongodb3.4以后要求配置服务器也创建副本集，不然集群搭建不成功。
在三台服务器上面添加配置文件：
[root@D2-POMS15 ~]# vi /usr/local/mongodb/conf/config.conf
## 配置文件内容
pidfilepath = /usr/local/mongodb/config/log/configsrv.pid
dbpath = /usr/local/mongodb/config/data
logpath = /usr/local/mongodb/config/log/congigsrv.log
logappend = true
bind_ip = 0.0.0.0
port = 21000
fork = true
#declare this is a config db of a cluster;
configsvr = true
#副本集名称
replSet=configs
#设置最大连接数
maxConns=20000
分别启动三台服务器的config server
[root@D2-POMS15 ~]# mongod -f /usr/local/mongodb/conf/config.conf
about to fork child process, waiting until server is ready for connections.
forked process: 15368
child process started successfully, parent exiting
登录任意一台配置服务器，初始化配置副本集
[root@D2-POMS15 ~]# mongo --port 21000
> config = {
... _id : "configs",
... members : [
... {_id : 0, host : "10.163.97.15:21000" },
... {_id : 1, host : "10.163.97.16:21000" },
... {_id : 2, host : "10.163.97.17:21000" }
... ]
... }
{
"_id" : "configs",
"members" : [
{
"_id" : 0,
"host" : "10.163.97.15:21000"
},
{
"_id" : 1,
"host" : "10.163.97.16:21000"
},
{
"_id" : 2,
"host" : "10.163.97.17:21000"
}
]
}
> rs.initiate(config)
{ "ok" : 1 }
其中，"_id" : "configs"应与配置文件中配置的replSet一致，"members" 中的 "host" 为三个节点的 ip 和 port。
4、配置分片副本集(三台机器)
设置第一个分片副本集
添加配置文件：
[root@D2-POMS15 ~]# vi /usr/local/mongodb/conf/shard1.conf
#配置文件内容
pidfilepath = /usr/local/mongodb/shard1/log/shard1.pid
dbpath = /usr/local/mongodb/shard1/data
logpath = /usr/local/mongodb/shard1/log/shard1.log
logappend = true
bind_ip = 0.0.0.0
port = 27001
fork = true
#打开web监控
httpinterface=true
rest=true
#副本集名称
replSet=shard1
#declare this is a shard db of a cluster;
shardsvr = true
#设置最大连接数
maxConns=20000
启动三台服务器的shard1 server
[root@D2-POMS15 ~]# mongod -f /usr/local/mongodb/conf/shard1.conf
about to fork child process, waiting until server is ready for connections.
forked process: 15497
child process started successfully, parent exiting
登陆一台服务器（不要在仲裁节点），初始化副本集
[root@D2-POMS15 ~]# mongo --port 27001
#使用admin数据库
> use admin
switched to db admin
#定义副本集配置，第三个节点的 "arbiterOnly":true 代表其为仲裁节点。
> config = {
... _id : "shard1",
... members : [
... {_id : 0, host : "10.163.97.15:27001" },
... {_id : 1, host : "10.163.97.16:27001" },
... {_id : 2, host : "10.163.97.17:27001" , arbiterOnly: true }
... ]
... }
{
"_id" : "shard1",
"members" : [
{
"_id" : 0,
"host" : "10.163.97.15:27001"
},
{
"_id" : 1,
"host" : "10.163.97.16:27001"
},
{
"_id" : 2,
"host" : "10.163.97.17:27001",
"arbiterOnly" : true
}
]
}
#初始化副本集配置
> rs.initiate(config);
{ "ok" : 1 }
设置第二个分片副本集
添加配置文件：
[root@D2-POMS15 ~]# vi /usr/local/mongodb/conf/shard2.conf
#配置文件内容
pidfilepath = /usr/local/mongodb/shard2/log/shard2.pid
dbpath = /usr/local/mongodb/shard2/data
logpath = /usr/local/mongodb/shard2/log/shard2.log
logappend = true
bind_ip = 0.0.0.0
port = 27002
fork = true
#打开web监控
httpinterface=true
rest=true
#副本集名称
replSet=shard2
#declare this is a shard db of a cluster;
shardsvr = true
#设置最大连接数
maxConns=20000
启动三台服务器的shard2 server：
[root@D2-POMS15 ~]# mongod -f /usr/local/mongodb/conf/shard2.conf
about to fork child process, waiting until server is ready for connections.
forked process: 15622
child process started successfully, parent exiting
登陆一台服务器（不要在仲裁节点），初始化副本集
[root@D2-POMS15 ~]# mongo --port 27002
> use admin
switched to db admin
> config = {
... _id : "shard2",
... members : [
... {_id : 0, host : "10.163.97.15:27002" , arbiterOnly: true },
... {_id : 1, host : "10.163.97.16:27002" },
... {_id : 2, host : "10.163.97.17:27002" }
... ]
... }
{
"_id" : "shard2",
"members" : [
{
"_id" : 0,
"host" : "10.163.97.15:27002",
"arbiterOnly" : true
},
{
"_id" : 1,
"host" : "10.163.97.16:27002"
},
{
"_id" : 2,
"host" : "10.163.97.17:27002"
}
]
}
> rs.initiate(config);
{ "ok" : 1 }
设置第三个分片副本集
添加配置文件：
[root@D2-POMS15 ~]# vi /usr/local/mongodb/conf/shard3.conf
#配置文件内容
pidfilepath = /usr/local/mongodb/shard3/log/shard3.pid
dbpath = /usr/local/mongodb/shard3/data
logpath = /usr/local/mongodb/shard3/log/shard3.log
logappend = true
bind_ip = 0.0.0.0
port = 27003
fork = true
#打开web监控
httpinterface=true
rest=true
#副本集名称
replSet=shard3
#declare this is a shard db of a cluster;
shardsvr = true
#设置最大连接数
maxConns=20000
启动三台服务器的shard3 server
[root@D2-POMS15 ~]# mongod -f /usr/local/mongodb/conf/shard3.conf
about to fork child process, waiting until server is ready for connections.
forked process: 15742
child process started successfully, parent exiting
登陆一台服务器（不要在仲裁节点），初始化副本集
> use admin
switched to db admin
> config = {
... _id : "shard3",
... members : [
... {_id : 0, host : "10.163.97.15:27003" },
... {_id : 1, host : "10.163.97.16:27003" , arbiterOnly: true},
... {_id : 2, host : "10.163.97.17:27003" }
... ]
... }
{
"_id" : "shard3",
"members" : [
{
"_id" : 0,
"host" : "10.163.97.15:27003"
},
{
"_id" : 1,
"host" : "10.163.97.16:27003",
"arbiterOnly" : true
},
{
"_id" : 2,
"host" : "10.163.97.17:27003"
}
]
}
> rs.initiate(config);
{ "ok" : 1 }
可以看到目前已经启动了配置服务器和分片服务器。
[root@D2-POMS15 ~]# ps -ef | grep mongo | grep -v grep
root 15368 1 0 15:52 ? 00:00:07 mongod -f /usr/local/mongodb/conf/config.conf
root 15497 1 0 16:00 ? 00:00:04 mongod -f /usr/local/mongodb/conf/shard1.conf
root 15622 1 0 16:06 ? 00:00:02 mongod -f /usr/local/mongodb/conf/shard2.conf
root 15742 1 0 16:21 ? 00:00:00 mongod -f /usr/local/mongodb/conf/shard3.conf
5、配置路由服务器 mongos
在三台服务器上面添加配置文件：
[root@D2-POMS15 ~]# vi /usr/local/mongodb/conf/mongos.conf
#内容
pidfilepath = /usr/local/mongodb/mongos/log/mongos.pid
logpath = /usr/local/mongodb/mongos/log/mongos.log
logappend = true
bind_ip = 0.0.0.0
port = 20000
fork = true
#监听的配置服务器,只能有1个或者3个 configs为配置服务器的副本集名字
configdb = configs/10.163.97.15:21000,10.163.97.16:21000,10.163.97.17:21000
#设置最大连接数
maxConns=20000
启动三台服务器的mongos server
[root@D2-POMS15 ~]# mongos -f /usr/local/mongodb/conf/mongos.conf
about to fork child process, waiting until server is ready for connections.
forked process: 20563
child process started successfully, parent exiting
[root@D2-POMS15 ~]# mongo --port 20000
mongos> db.stats()
{
"raw" : {
"shard1/10.163.97.15:27001,10.163.97.16:27001" : {
"db" : "admin",
"collections" : 1,
"views" : 0,
"objects" : 3,
"avgObjSize" : 146.66666666666666,
"dataSize" : 440,
"storageSize" : 36864,
"numExtents" : 0,
"indexes" : 2,
"indexSize" : 65536,
"ok" : 1,
"$gleStats" : {
"lastOpTime" : Timestamp(0, 0),
"electionId" : ObjectId("7fffffff0000000000000001")
}
},
"shard2/10.163.97.16:27002,10.163.97.17:27002" : {
"db" : "admin",
"collections" : 1,
"views" : 0,
"objects" : 2,
"avgObjSize" : 114,
"dataSize" : 228,
"storageSize" : 16384,
"numExtents" : 0,
"indexes" : 2,
"indexSize" : 32768,
"ok" : 1,
"$gleStats" : {
"lastOpTime" : Timestamp(0, 0),
"electionId" : ObjectId("7fffffff0000000000000001")
}
},
"shard3/10.163.97.15:27003,10.163.97.17:27003" : {
"db" : "admin",
"collections" : 1,
"views" : 0,
"objects" : 2,
"avgObjSize" : 114,
"dataSize" : 228,
"storageSize" : 16384,
"numExtents" : 0,
"indexes" : 2,
"indexSize" : 32768,
"ok" : 1,
"$gleStats" : {
"lastOpTime" : Timestamp(0, 0),
"electionId" : ObjectId("7fffffff0000000000000002")
}
}
},
"objects" : 7,
"avgObjSize" : 127.71428571428571,
"dataSize" : 896,
"storageSize" : 69632,
"numExtents" : 0,
"indexes" : 6,
"indexSize" : 131072,
"fileSize" : 0,
"extentFreeList" : {
"num" : 0,
"totalSize" : 0
},
"ok" : 1
}
6、启用分片
目前搭建了mongodb配置服务器、路由服务器，各个分片服务器，不过应用程序连接到mongos路由服务器并不能使用分片机制，还需要在路由服务器里设置分片配置，让分片生效。
登陆任意一台mongos
[root@D2-POMS15 ~]# mongo --port 20000
#使用admin数据库
mongos> use admin
switched to db admin
#串联路由服务器与分配副本集
mongos> sh.addShard("shard1/10.163.97.15:27001,10.163.97.16:27001,10.163.97.17:27001")
{ "shardAdded" : "shard1", "ok" : 1 }
mongos> sh.addShard("shard2/10.163.97.15:27002,10.163.97.16:27002,10.163.97.17:27002")
{ "shardAdded" : "shard2", "ok" : 1 }
mongos> sh.addShard("shard3/10.163.97.15:27003,10.163.97.16:27003,10.163.97.17:27003")
{ "shardAdded" : "shard3", "ok" : 1 }
#查看集群状态
mongos> sh.status()
--- Sharding Status ---
sharding version: {
"_id" : 1,
"minCompatibleVersion" : 5,
"currentVersion" : 6,
"clusterId" : ObjectId("599d34bf612249caec3fc9fe")
}
shards:
{ "_id" : "shard1", "host" : "shard1/10.163.97.15:27001,10.163.97.16:27001", "state" : 1 }
{ "_id" : "shard2", "host" : "shard2/10.163.97.16:27002,10.163.97.17:27002", "state" : 1 }
{ "_id" : "shard3", "host" : "shard3/10.163.97.15:27003,10.163.97.17:27003", "state" : 1 }
active mongoses:
"3.4.7" : 1
autosplit:
Currently enabled: yes
balancer:
Currently enabled: yes
Currently running: no
Balancer lock taken at Wed Aug 23 2017 15:54:40 GMT+0800 (CST) by ConfigServer:Balancer
Failed balancer rounds in last 5 attempts: 0
Migration Results for the last 24 hours:
No recent migrations
databases:
7、测试
目前配置服务、路由服务、分片服务、副本集服务都已经串联起来了，但我们的目的是希望插入数据，数据能够自动分片。连接在mongos上，准备让指定的数据库、指定的集合分片生效。
[root@D2-POMS15 ~]# mongo --port 20000
mongos> use admin
switched to db admin
#指定testdb分片生效
mongos> db.runCommand({enablesharding :"testdb"});
{ "ok" : 1 }
#指定数据库里需要分片的集合和片键
mongos> db.runCommand( { shardcollection : "testdb.table1",key : {id: 1} } )
{ "collectionsharded" : "testdb.table1", "ok" : 1 }
mongos> sh.status()
--- Sharding Status ---
sharding version: {
"_id" : 1,
"minCompatibleVersion" : 5,
"currentVersion" : 6,
"clusterId" : ObjectId("599d34bf612249caec3fc9fe")
}
shards:
{ "_id" : "shard1", "host" : "shard1/10.163.97.15:27001,10.163.97.16:27001", "state" : 1 }
{ "_id" : "shard2", "host" : "shard2/10.163.97.16:27002,10.163.97.17:27002", "state" : 1 }
{ "_id" : "shard3", "host" : "shard3/10.163.97.15:27003,10.163.97.17:27003", "state" : 1 }
active mongoses:
"3.4.7" : 1
autosplit:
Currently enabled: yes
balancer:
Currently enabled: yes
Currently running: no
Balancer lock taken at Wed Aug 23 2017 15:54:40 GMT+0800 (CST) by ConfigServer:Balancer
Failed balancer rounds in last 5 attempts: 0
Migration Results for the last 24 hours:
4 : Success
databases:
{ "_id" : "testdb", "primary" : "shard1", "partitioned" : true }
testdb.table1
shard key: { "id" : 1 }
unique: false
balancing: true
chunks:
shard1 1
{ "id" : { "$minKey" : 1 } } -->> { "id" : { "$maxKey" : 1 } } on : shard1 Timestamp(1, 0)
以上就是设置testdb的 table1 表需要分片，根据 id 自动分片到 shard1 ，shard2，shard3 上面去。要这样设置是因为不是所有mongodb 的数据库和表 都需要分片！
测试分片：
#连接mongos服务器
[root@D2-POMS15 ~]# mongo --port 20000
#使用testdb
mongos> use testdb
switched to db testdb
#插入测试数据
mongos> for(var i=1;i<=100000;i++){db.table1.insert({id:i,"test1":"testval1"})}
WriteResult({ "nInserted" : 1 })
#查看分片情况
mongos> sh.status()
--- Sharding Status ---
sharding version: {
"_id" : 1,
"minCompatibleVersion" : 5,
"currentVersion" : 6,
"clusterId" : ObjectId("599d34bf612249caec3fc9fe")
}
shards:
{ "_id" : "shard1", "host" : "shard1/10.163.97.15:27001,10.163.97.16:27001", "state" : 1 }
{ "_id" : "shard2", "host" : "shard2/10.163.97.16:27002,10.163.97.17:27002", "state" : 1 }
{ "_id" : "shard3", "host" : "shard3/10.163.97.15:27003,10.163.97.17:27003", "state" : 1 }
active mongoses:
"3.4.7" : 1
autosplit:
Currently enabled: yes
balancer:
Currently enabled: yes
Currently running: no
Balancer lock taken at Wed Aug 23 2017 15:54:40 GMT+0800 (CST) by ConfigServer:Balancer
Failed balancer rounds in last 5 attempts: 0
Migration Results for the last 24 hours:
6 : Success
databases:
{ "_id" : "testdb", "primary" : "shard1", "partitioned" : true }
testdb.table1
shard key: { "id" : 1 }
unique: false
balancing: true
chunks:
shard1 1
shard2 1
shard3 1
{ "id" : { "$minKey" : 1 } } -->> { "id" : 2 } on : shard2 Timestamp(2, 0)
{ "id" : 2 } -->> { "id" : 20 } on : shard3 Timestamp(3, 0)
{ "id" : 20 } -->> { "id" : { "$maxKey" : 1 } } on : shard1 Timestamp(3, 1)
可以看到这里分片很不均衡，原因是默认的chunkSize为64M，这里的数据量没有达到64M，可以修改一下chunkSize的大小，方便测试：
[root@D2-POMS15 ~]# mongo --port 20000
mongos> use config
switched to db config
mongos> db.settings.save( { _id:"chunksize", value: 1 } )
WriteResult({ "nMatched" : 0, "nUpserted" : 1, "nModified" : 0, "_id" : "chunksize" })
mongos> db.settings.find();
{ "_id" : "balancer", "stopped" : false, "mode" : "full" }
{ "_id" : "chunksize", "value" : 1 }
修改后重新来测试：
mongos> use testdb
switched to db testdb
mongos> db.table1.drop();
true
mongos> use admin
switched to db admin
mongos> db.runCommand( { shardcollection : "testdb.table1",key : {id: 1} } )
{ "collectionsharded" : "testdb.table1", "ok" : 1 }
mongos> use testdb
switched to db testdb
mongos> for(var i=1;i<=100000;i++){db.table1.insert({id:i,"test1":"testval1"})}
WriteResult({ "nInserted" : 1 })
mongos> sh.status()
--- Sharding Status ---
sharding version: {
"_id" : 1,
"minCompatibleVersion" : 5,
"currentVersion" : 6,
"clusterId" : ObjectId("599d34bf612249caec3fc9fe")
}
shards:
{ "_id" : "shard1", "host" : "shard1/10.163.97.15:27001,10.163.97.16:27001", "state" : 1 }
{ "_id" : "shard2", "host" : "shard2/10.163.97.16:27002,10.163.97.17:27002", "state" : 1 }
{ "_id" : "shard3", "host" : "shard3/10.163.97.15:27003,10.163.97.17:27003", "state" : 1 }
active mongoses:
"3.4.7" : 1
autosplit:
Currently enabled: yes
balancer:
Currently enabled: yes
Currently running: no
Balancer lock taken at Wed Aug 23 2017 15:54:40 GMT+0800 (CST) by ConfigServer:Balancer
Failed balancer rounds in last 5 attempts: 0
Migration Results for the last 24 hours:
14 : Success
databases:
{ "_id" : "testdb", "primary" : "shard1", "partitioned" : true }
testdb.table1
shard key: { "id" : 1 }
unique: false
balancing: true
chunks:
shard1 4
shard2 4
shard3 3
{ "id" : { "$minKey" : 1 } } -->> { "id" : 2 } on : shard2 Timestamp(5, 1)
{ "id" : 2 } -->> { "id" : 20 } on : shard3 Timestamp(6, 1)
{ "id" : 20 } -->> { "id" : 9729 } on : shard1 Timestamp(7, 1)
{ "id" : 9729 } -->> { "id" : 21643 } on : shard1 Timestamp(3, 3)
{ "id" : 21643 } -->> { "id" : 31352 } on : shard2 Timestamp(4, 2)
{ "id" : 31352 } -->> { "id" : 43021 } on : shard2 Timestamp(4, 3)
{ "id" : 43021 } -->> { "id" : 52730 } on : shard3 Timestamp(5, 2)
{ "id" : 52730 } -->> { "id" : 64695 } on : shard3 Timestamp(5, 3)
{ "id" : 64695 } -->> { "id" : 74404 } on : shard1 Timestamp(6, 2)
{ "id" : 74404 } -->> { "id" : 87088 } on : shard1 Timestamp(6, 3)
{ "id" : 87088 } -->> { "id" : { "$maxKey" : 1 } } on : shard2 Timestamp(7, 0)
mongos> db.table1.stats()
{
"sharded" : true,
"capped" : false,
"ns" : "testdb.table1",
"count" : 100000,
"size" : 5400000,
"storageSize" : 1736704,
"totalIndexSize" : 2191360,
"indexSizes" : {
"_id_" : 946176,
"id_1" : 1245184
},
"avgObjSize" : 54,
"nindexes" : 2,
"nchunks" : 11,
"shards" : {
"shard1" : {
"ns" : "testdb.table1",
"size" : 2376864,
"count" : 44016,
"avgObjSize" : 54,
"storageSize" : 753664,
"capped" : false,
"nindexes" : 2,
"totalIndexSize" : 933888,
"indexSizes" : {
"_id_" : 405504,
"id_1" : 528384
},
"ok" : 1
},
"shard2" : {
"ns" : "testdb.table1",
"size" : 1851768,
"count" : 34292,
"avgObjSize" : 54,
"storageSize" : 606208,
"capped" : false,
"nindexes" : 2,
"totalIndexSize" : 774144,
"indexSizes" : {
"_id_" : 335872,
"id_1" : 438272
},
"ok" : 1
},
"shard3" : {
"ns" : "testdb.table1",
"size" : 1171368,
"count" : 21692,
"avgObjSize" : 54,
"storageSize" : 376832,
"capped" : false,
新闻标题：MongoDB之分片
转载来源：http://azwzsj.com/article/joesej.html
操作系统信息：
| IP | 操作系统 | MongoDB |
| 10.163.91.15 | RHLE6.5_x64 | mongodb-linux-x86_64-rhel62-3.4.7.tgz |
| 10.163.91.16 | RHLE6.5_x64 | mongodb-linux-x86_64-rhel62-3.4.7.tgz |
| 10.163.91.17 | RHLE6.5_x64 | mongodb-linux-x86_64-rhel62-3.4.7.tgz |
服务器规划：
| 10.163.97.15 | 10.163.97.16 | 10.163.97.17 | 端口 |
| mongos | mongos | mongos | 20000 |
| config server | config server | config server | 21000 |
| shard server1 主节点 | shard server1 副节点 | shard server1 仲裁 | 27001 |
| shard server2 仲裁 | shard server2 主节点 | shard server2 副节点 | 27002 |
| shard server3 副节点 | shard server3 仲裁 | shard server3 主节点 | 27003 |
从上表可以看到有四个组件：mongos、config server、shard、replica set。
mongos：数据库集群请求的入口，所有的请求都通过mongos进行协调，不需要在应用程序添加一个路由选择器，mongos自己就是一个请求分发中心，它负责把对应的数据请求转发到对应的shard服务器上。在生产环境通常有多mongos作为请求的入口，防止其中一个挂掉所有的mongodb请求都没有办法操作。
config server：顾名思义为配置服务器，存储所有数据库元信息（路由、分片）的配置。mongos本身没有物理存储分片服务器和数据路由信息，只是缓存在内存里，配置服务器则实际存储这些数据。mongos第一次启动或者关掉重启就会从 config server 加载配置信息，以后如果配置服务器信息变化会通知到所有的 mongos 更新自己的状态，这样 mongos 就能继续准确路由。在生产环境通常有多个 config server 配置服务器（必须配置为１个或者３个），因为它存储了分片路由的元数据，防止数据丢失！
shard：分片（sharding）是指将数据库拆分，将其分散在不同的机器上的过程。将数据分散到不同的机器上，不需要功能强大的服务器就可以存储更多的数据和处理更大的负载。基本思想就是将集合切成小块，这些块分散到若干片里，每个片只负责总数据的一部分，最后通过一个均衡器来对各个分片进行均衡（数据迁移）。
replica set：中文翻译副本集，其实就是shard的备份，防止shard挂掉之后数据丢失。复制提供了数据的冗余备份，并在多个服务器上存储数据副本，提高了数据的可用性， 并可以保证数据的安全性。
仲裁者（Arbiter）：是复制集中的一个MongoDB实例，它并不保存数据。仲裁节点使用最小的资源，不能将Arbiter部署在同一个数据集节点中，可以部署在其他应用服务器或者监视服务器中，也可部署在单独的虚拟机中。为了确保复制集中有奇数的投票成员（包括primary），需要添加仲裁节点做为投票，否则primary不能运行时不会自动切换primary。
简单了解之后，可以这样总结一下，应用请求mongos来操作mongodb的增删改查，配置服务器存储数据库元信息，并且和mongos做同步，数据最终存入在shard（分片）上，为了防止数据丢失同步在副本集中存储了一份，仲裁在数据存储到分片的时候决定存储到哪个节点。
总共规划了mongos 3个， config server 3个，数据分3片 shard server 3个，每个shard 有一个副本一个仲裁也就是 3 * 2 = 6 个，总共需要部署15个实例。这些实例可以部署在独立机器也可以部署在一台机器，我们这里测试资源有限，只准备了 3台机器，在同一台机器只要端口不同就可以了。
2、安装mongodb
分别在3台机器上面安装mongodb
[root@D2-POMS15 ~]# tar -xvzf mongodb-linux-x86_64-rhel62-3.4.7.tgz -C /usr/local/
[root@D2-POMS15 ~]# mv /usr/local/mongodb-linux-x86_64-rhel62-3.4.7/ /usr/local/mongodb
配置环境变量
[root@D2-POMS15 ~]# vim .bash_profile
export PATH=$PATH:/usr/local/mongodb/bin/
[root@D2-POMS15 ~]# source .bash_profile
分别在每台机器建立conf、mongos、config、shard1、shard2、shard3六个目录，因为mongos不存储数据，只需要建立日志文件目录即可。
[root@D2-POMS15 ~]# mkdir -p /usr/local/mongodb/conf
[root@D2-POMS15 ~]# mkdir -p /usr/local/mongodb/mongos/log
[root@D2-POMS15 ~]# mkdir -p /usr/local/mongodb/config/data
[root@D2-POMS15 ~]# mkdir -p /usr/local/mongodb/config/log
[root@D2-POMS15 ~]# mkdir -p /usr/local/mongodb/shard1/data
[root@D2-POMS15 ~]# mkdir -p /usr/local/mongodb/shard1/log
[root@D2-POMS15 ~]# mkdir -p /usr/local/mongodb/shard2/data
[root@D2-POMS15 ~]# mkdir -p /usr/local/mongodb/shard2/log
[root@D2-POMS15 ~]# mkdir -p /usr/local/mongodb/shard3/data
[root@D2-POMS15 ~]# mkdir -p /usr/local/mongodb/shard3/log
3、config server配置服务器
mongodb3.4以后要求配置服务器也创建副本集，不然集群搭建不成功。
在三台服务器上面添加配置文件：
[root@D2-POMS15 ~]# vi /usr/local/mongodb/conf/config.conf
## 配置文件内容
pidfilepath = /usr/local/mongodb/config/log/configsrv.pid
dbpath = /usr/local/mongodb/config/data
logpath = /usr/local/mongodb/config/log/congigsrv.log
logappend = true
bind_ip = 0.0.0.0
port = 21000
fork = true
#declare this is a config db of a cluster;
configsvr = true
#副本集名称
replSet=configs
#设置最大连接数
maxConns=20000
分别启动三台服务器的config server
[root@D2-POMS15 ~]# mongod -f /usr/local/mongodb/conf/config.conf
about to fork child process, waiting until server is ready for connections.
forked process: 15368
child process started successfully, parent exiting
登录任意一台配置服务器，初始化配置副本集
[root@D2-POMS15 ~]# mongo --port 21000
> config = {
... _id : "configs",
... members : [
... {_id : 0, host : "10.163.97.15:21000" },
... {_id : 1, host : "10.163.97.16:21000" },
... {_id : 2, host : "10.163.97.17:21000" }
... ]
... }
{
"_id" : "configs",
"members" : [
{
"_id" : 0,
"host" : "10.163.97.15:21000"
},
{
"_id" : 1,
"host" : "10.163.97.16:21000"
},
{
"_id" : 2,
"host" : "10.163.97.17:21000"
}
]
}
> rs.initiate(config)
{ "ok" : 1 }
其中，"_id" : "configs"应与配置文件中配置的replSet一致，"members" 中的 "host" 为三个节点的 ip 和 port。
4、配置分片副本集(三台机器)
设置第一个分片副本集
添加配置文件：
[root@D2-POMS15 ~]# vi /usr/local/mongodb/conf/shard1.conf
#配置文件内容
pidfilepath = /usr/local/mongodb/shard1/log/shard1.pid
dbpath = /usr/local/mongodb/shard1/data
logpath = /usr/local/mongodb/shard1/log/shard1.log
logappend = true
bind_ip = 0.0.0.0
port = 27001
fork = true
#打开web监控
httpinterface=true
rest=true
#副本集名称
replSet=shard1
#declare this is a shard db of a cluster;
shardsvr = true
#设置最大连接数
maxConns=20000
启动三台服务器的shard1 server
[root@D2-POMS15 ~]# mongod -f /usr/local/mongodb/conf/shard1.conf
about to fork child process, waiting until server is ready for connections.
forked process: 15497
child process started successfully, parent exiting
登陆一台服务器（不要在仲裁节点），初始化副本集
[root@D2-POMS15 ~]# mongo --port 27001
#使用admin数据库
> use admin
switched to db admin
#定义副本集配置，第三个节点的 "arbiterOnly":true 代表其为仲裁节点。
> config = {
... _id : "shard1",
... members : [
... {_id : 0, host : "10.163.97.15:27001" },
... {_id : 1, host : "10.163.97.16:27001" },
... {_id : 2, host : "10.163.97.17:27001" , arbiterOnly: true }
... ]
... }
{
"_id" : "shard1",
"members" : [
{
"_id" : 0,
"host" : "10.163.97.15:27001"
},
{
"_id" : 1,
"host" : "10.163.97.16:27001"
},
{
"_id" : 2,
"host" : "10.163.97.17:27001",
"arbiterOnly" : true
}
]
}
#初始化副本集配置
> rs.initiate(config);
{ "ok" : 1 }
设置第二个分片副本集
添加配置文件：
[root@D2-POMS15 ~]# vi /usr/local/mongodb/conf/shard2.conf
#配置文件内容
pidfilepath = /usr/local/mongodb/shard2/log/shard2.pid
dbpath = /usr/local/mongodb/shard2/data
logpath = /usr/local/mongodb/shard2/log/shard2.log
logappend = true
bind_ip = 0.0.0.0
port = 27002
fork = true
#打开web监控
httpinterface=true
rest=true
#副本集名称
replSet=shard2
#declare this is a shard db of a cluster;
shardsvr = true
#设置最大连接数
maxConns=20000
启动三台服务器的shard2 server：
[root@D2-POMS15 ~]# mongod -f /usr/local/mongodb/conf/shard2.conf
about to fork child process, waiting until server is ready for connections.
forked process: 15622
child process started successfully, parent exiting
登陆一台服务器（不要在仲裁节点），初始化副本集
[root@D2-POMS15 ~]# mongo --port 27002
> use admin
switched to db admin
> config = {
... _id : "shard2",
... members : [
... {_id : 0, host : "10.163.97.15:27002" , arbiterOnly: true },
... {_id : 1, host : "10.163.97.16:27002" },
... {_id : 2, host : "10.163.97.17:27002" }
... ]
... }
{
"_id" : "shard2",
"members" : [
{
"_id" : 0,
"host" : "10.163.97.15:27002",
"arbiterOnly" : true
},
{
"_id" : 1,
"host" : "10.163.97.16:27002"
},
{
"_id" : 2,
"host" : "10.163.97.17:27002"
}
]
}
> rs.initiate(config);
{ "ok" : 1 }
设置第三个分片副本集
添加配置文件：
[root@D2-POMS15 ~]# vi /usr/local/mongodb/conf/shard3.conf
#配置文件内容
pidfilepath = /usr/local/mongodb/shard3/log/shard3.pid
dbpath = /usr/local/mongodb/shard3/data
logpath = /usr/local/mongodb/shard3/log/shard3.log
logappend = true
bind_ip = 0.0.0.0
port = 27003
fork = true
#打开web监控
httpinterface=true
rest=true
#副本集名称
replSet=shard3
#declare this is a shard db of a cluster;
shardsvr = true
#设置最大连接数
maxConns=20000
启动三台服务器的shard3 server
[root@D2-POMS15 ~]# mongod -f /usr/local/mongodb/conf/shard3.conf
about to fork child process, waiting until server is ready for connections.
forked process: 15742
child process started successfully, parent exiting
登陆一台服务器（不要在仲裁节点），初始化副本集
> use admin
switched to db admin
> config = {
... _id : "shard3",
... members : [
... {_id : 0, host : "10.163.97.15:27003" },
... {_id : 1, host : "10.163.97.16:27003" , arbiterOnly: true},
... {_id : 2, host : "10.163.97.17:27003" }
... ]
... }
{
"_id" : "shard3",
"members" : [
{
"_id" : 0,
"host" : "10.163.97.15:27003"
},
{
"_id" : 1,
"host" : "10.163.97.16:27003",
"arbiterOnly" : true
},
{
"_id" : 2,
"host" : "10.163.97.17:27003"
}
]
}
> rs.initiate(config);
{ "ok" : 1 }
可以看到目前已经启动了配置服务器和分片服务器。
[root@D2-POMS15 ~]# ps -ef | grep mongo | grep -v grep
root 15368 1 0 15:52 ? 00:00:07 mongod -f /usr/local/mongodb/conf/config.conf
root 15497 1 0 16:00 ? 00:00:04 mongod -f /usr/local/mongodb/conf/shard1.conf
root 15622 1 0 16:06 ? 00:00:02 mongod -f /usr/local/mongodb/conf/shard2.conf
root 15742 1 0 16:21 ? 00:00:00 mongod -f /usr/local/mongodb/conf/shard3.conf
5、配置路由服务器 mongos
在三台服务器上面添加配置文件：
[root@D2-POMS15 ~]# vi /usr/local/mongodb/conf/mongos.conf
#内容
pidfilepath = /usr/local/mongodb/mongos/log/mongos.pid
logpath = /usr/local/mongodb/mongos/log/mongos.log
logappend = true
bind_ip = 0.0.0.0
port = 20000
fork = true
#监听的配置服务器,只能有1个或者3个 configs为配置服务器的副本集名字
configdb = configs/10.163.97.15:21000,10.163.97.16:21000,10.163.97.17:21000
#设置最大连接数
maxConns=20000
启动三台服务器的mongos server
[root@D2-POMS15 ~]# mongos -f /usr/local/mongodb/conf/mongos.conf
about to fork child process, waiting until server is ready for connections.
forked process: 20563
child process started successfully, parent exiting
[root@D2-POMS15 ~]# mongo --port 20000
mongos> db.stats()
{
"raw" : {
"shard1/10.163.97.15:27001,10.163.97.16:27001" : {
"db" : "admin",
"collections" : 1,
"views" : 0,
"objects" : 3,
"avgObjSize" : 146.66666666666666,
"dataSize" : 440,
"storageSize" : 36864,
"numExtents" : 0,
"indexes" : 2,
"indexSize" : 65536,
"ok" : 1,
"$gleStats" : {
"lastOpTime" : Timestamp(0, 0),
"electionId" : ObjectId("7fffffff0000000000000001")
}
},
"shard2/10.163.97.16:27002,10.163.97.17:27002" : {
"db" : "admin",
"collections" : 1,
"views" : 0,
"objects" : 2,
"avgObjSize" : 114,
"dataSize" : 228,
"storageSize" : 16384,
"numExtents" : 0,
"indexes" : 2,
"indexSize" : 32768,
"ok" : 1,
"$gleStats" : {
"lastOpTime" : Timestamp(0, 0),
"electionId" : ObjectId("7fffffff0000000000000001")
}
},
"shard3/10.163.97.15:27003,10.163.97.17:27003" : {
"db" : "admin",
"collections" : 1,
"views" : 0,
"objects" : 2,
"avgObjSize" : 114,
"dataSize" : 228,
"storageSize" : 16384,
"numExtents" : 0,
"indexes" : 2,
"indexSize" : 32768,
"ok" : 1,
"$gleStats" : {
"lastOpTime" : Timestamp(0, 0),
"electionId" : ObjectId("7fffffff0000000000000002")
}
}
},
"objects" : 7,
"avgObjSize" : 127.71428571428571,
"dataSize" : 896,
"storageSize" : 69632,
"numExtents" : 0,
"indexes" : 6,
"indexSize" : 131072,
"fileSize" : 0,
"extentFreeList" : {
"num" : 0,
"totalSize" : 0
},
"ok" : 1
}
6、启用分片
目前搭建了mongodb配置服务器、路由服务器，各个分片服务器，不过应用程序连接到mongos路由服务器并不能使用分片机制，还需要在路由服务器里设置分片配置，让分片生效。
登陆任意一台mongos
[root@D2-POMS15 ~]# mongo --port 20000
#使用admin数据库
mongos> use admin
switched to db admin
#串联路由服务器与分配副本集
mongos> sh.addShard("shard1/10.163.97.15:27001,10.163.97.16:27001,10.163.97.17:27001")
{ "shardAdded" : "shard1", "ok" : 1 }
mongos> sh.addShard("shard2/10.163.97.15:27002,10.163.97.16:27002,10.163.97.17:27002")
{ "shardAdded" : "shard2", "ok" : 1 }
mongos> sh.addShard("shard3/10.163.97.15:27003,10.163.97.16:27003,10.163.97.17:27003")
{ "shardAdded" : "shard3", "ok" : 1 }
#查看集群状态
mongos> sh.status()
--- Sharding Status ---
sharding version: {
"_id" : 1,
"minCompatibleVersion" : 5,
"currentVersion" : 6,
"clusterId" : ObjectId("599d34bf612249caec3fc9fe")
}
shards:
{ "_id" : "shard1", "host" : "shard1/10.163.97.15:27001,10.163.97.16:27001", "state" : 1 }
{ "_id" : "shard2", "host" : "shard2/10.163.97.16:27002,10.163.97.17:27002", "state" : 1 }
{ "_id" : "shard3", "host" : "shard3/10.163.97.15:27003,10.163.97.17:27003", "state" : 1 }
active mongoses:
"3.4.7" : 1
autosplit:
Currently enabled: yes
balancer:
Currently enabled: yes
Currently running: no
Balancer lock taken at Wed Aug 23 2017 15:54:40 GMT+0800 (CST) by ConfigServer:Balancer
Failed balancer rounds in last 5 attempts: 0
Migration Results for the last 24 hours:
No recent migrations
databases:
7、测试
目前配置服务、路由服务、分片服务、副本集服务都已经串联起来了，但我们的目的是希望插入数据，数据能够自动分片。连接在mongos上，准备让指定的数据库、指定的集合分片生效。
[root@D2-POMS15 ~]# mongo --port 20000
mongos> use admin
switched to db admin
#指定testdb分片生效
mongos> db.runCommand({enablesharding :"testdb"});
{ "ok" : 1 }
#指定数据库里需要分片的集合和片键
mongos> db.runCommand( { shardcollection : "testdb.table1",key : {id: 1} } )
{ "collectionsharded" : "testdb.table1", "ok" : 1 }
mongos> sh.status()
--- Sharding Status ---
sharding version: {
"_id" : 1,
"minCompatibleVersion" : 5,
"currentVersion" : 6,
"clusterId" : ObjectId("599d34bf612249caec3fc9fe")
}
shards:
{ "_id" : "shard1", "host" : "shard1/10.163.97.15:27001,10.163.97.16:27001", "state" : 1 }
{ "_id" : "shard2", "host" : "shard2/10.163.97.16:27002,10.163.97.17:27002", "state" : 1 }
{ "_id" : "shard3", "host" : "shard3/10.163.97.15:27003,10.163.97.17:27003", "state" : 1 }
active mongoses:
"3.4.7" : 1
autosplit:
Currently enabled: yes
balancer:
Currently enabled: yes
Currently running: no
Balancer lock taken at Wed Aug 23 2017 15:54:40 GMT+0800 (CST) by ConfigServer:Balancer
Failed balancer rounds in last 5 attempts: 0
Migration Results for the last 24 hours:
4 : Success
databases:
{ "_id" : "testdb", "primary" : "shard1", "partitioned" : true }
testdb.table1
shard key: { "id" : 1 }
unique: false
balancing: true
chunks:
shard1 1
{ "id" : { "$minKey" : 1 } } -->> { "id" : { "$maxKey" : 1 } } on : shard1 Timestamp(1, 0)
以上就是设置testdb的 table1 表需要分片，根据 id 自动分片到 shard1 ，shard2，shard3 上面去。要这样设置是因为不是所有mongodb 的数据库和表 都需要分片！
测试分片：
#连接mongos服务器
[root@D2-POMS15 ~]# mongo --port 20000
#使用testdb
mongos> use testdb
switched to db testdb
#插入测试数据
mongos> for(var i=1;i<=100000;i++){db.table1.insert({id:i,"test1":"testval1"})}
WriteResult({ "nInserted" : 1 })
#查看分片情况
mongos> sh.status()
--- Sharding Status ---
sharding version: {
"_id" : 1,
"minCompatibleVersion" : 5,
"currentVersion" : 6,
"clusterId" : ObjectId("599d34bf612249caec3fc9fe")
}
shards:
{ "_id" : "shard1", "host" : "shard1/10.163.97.15:27001,10.163.97.16:27001", "state" : 1 }
{ "_id" : "shard2", "host" : "shard2/10.163.97.16:27002,10.163.97.17:27002", "state" : 1 }
{ "_id" : "shard3", "host" : "shard3/10.163.97.15:27003,10.163.97.17:27003", "state" : 1 }
active mongoses:
"3.4.7" : 1
autosplit:
Currently enabled: yes
balancer:
Currently enabled: yes
Currently running: no
Balancer lock taken at Wed Aug 23 2017 15:54:40 GMT+0800 (CST) by ConfigServer:Balancer
Failed balancer rounds in last 5 attempts: 0
Migration Results for the last 24 hours:
6 : Success
databases:
{ "_id" : "testdb", "primary" : "shard1", "partitioned" : true }
testdb.table1
shard key: { "id" : 1 }
unique: false
balancing: true
chunks:
shard1 1
shard2 1
shard3 1
{ "id" : { "$minKey" : 1 } } -->> { "id" : 2 } on : shard2 Timestamp(2, 0)
{ "id" : 2 } -->> { "id" : 20 } on : shard3 Timestamp(3, 0)
{ "id" : 20 } -->> { "id" : { "$maxKey" : 1 } } on : shard1 Timestamp(3, 1)
可以看到这里分片很不均衡，原因是默认的chunkSize为64M，这里的数据量没有达到64M，可以修改一下chunkSize的大小，方便测试：
[root@D2-POMS15 ~]# mongo --port 20000
mongos> use config
switched to db config
mongos> db.settings.save( { _id:"chunksize", value: 1 } )
WriteResult({ "nMatched" : 0, "nUpserted" : 1, "nModified" : 0, "_id" : "chunksize" })
mongos> db.settings.find();
{ "_id" : "balancer", "stopped" : false, "mode" : "full" }
{ "_id" : "chunksize", "value" : 1 }
修改后重新来测试：
mongos> use testdb
switched to db testdb
mongos> db.table1.drop();
true
mongos> use admin
switched to db admin
mongos> db.runCommand( { shardcollection : "testdb.table1",key : {id: 1} } )
{ "collectionsharded" : "testdb.table1", "ok" : 1 }
mongos> use testdb
switched to db testdb
mongos> for(var i=1;i<=100000;i++){db.table1.insert({id:i,"test1":"testval1"})}
WriteResult({ "nInserted" : 1 })
mongos> sh.status()
--- Sharding Status ---
sharding version: {
"_id" : 1,
"minCompatibleVersion" : 5,
"currentVersion" : 6,
"clusterId" : ObjectId("599d34bf612249caec3fc9fe")
}
shards:
{ "_id" : "shard1", "host" : "shard1/10.163.97.15:27001,10.163.97.16:27001", "state" : 1 }
{ "_id" : "shard2", "host" : "shard2/10.163.97.16:27002,10.163.97.17:27002", "state" : 1 }
{ "_id" : "shard3", "host" : "shard3/10.163.97.15:27003,10.163.97.17:27003", "state" : 1 }
active mongoses:
"3.4.7" : 1
autosplit:
Currently enabled: yes
balancer:
Currently enabled: yes
Currently running: no
Balancer lock taken at Wed Aug 23 2017 15:54:40 GMT+0800 (CST) by ConfigServer:Balancer
Failed balancer rounds in last 5 attempts: 0
Migration Results for the last 24 hours:
14 : Success
databases:
{ "_id" : "testdb", "primary" : "shard1", "partitioned" : true }
testdb.table1
shard key: { "id" : 1 }
unique: false
balancing: true
chunks:
shard1 4
shard2 4
shard3 3
{ "id" : { "$minKey" : 1 } } -->> { "id" : 2 } on : shard2 Timestamp(5, 1)
{ "id" : 2 } -->> { "id" : 20 } on : shard3 Timestamp(6, 1)
{ "id" : 20 } -->> { "id" : 9729 } on : shard1 Timestamp(7, 1)
{ "id" : 9729 } -->> { "id" : 21643 } on : shard1 Timestamp(3, 3)
{ "id" : 21643 } -->> { "id" : 31352 } on : shard2 Timestamp(4, 2)
{ "id" : 31352 } -->> { "id" : 43021 } on : shard2 Timestamp(4, 3)
{ "id" : 43021 } -->> { "id" : 52730 } on : shard3 Timestamp(5, 2)
{ "id" : 52730 } -->> { "id" : 64695 } on : shard3 Timestamp(5, 3)
{ "id" : 64695 } -->> { "id" : 74404 } on : shard1 Timestamp(6, 2)
{ "id" : 74404 } -->> { "id" : 87088 } on : shard1 Timestamp(6, 3)
{ "id" : 87088 } -->> { "id" : { "$maxKey" : 1 } } on : shard2 Timestamp(7, 0)
mongos> db.table1.stats()
{
"sharded" : true,
"capped" : false,
"ns" : "testdb.table1",
"count" : 100000,
"size" : 5400000,
"storageSize" : 1736704,
"totalIndexSize" : 2191360,
"indexSizes" : {
"_id_" : 946176,
"id_1" : 1245184
},
"avgObjSize" : 54,
"nindexes" : 2,
"nchunks" : 11,
"shards" : {
"shard1" : {
"ns" : "testdb.table1",
"size" : 2376864,
"count" : 44016,
"avgObjSize" : 54,
"storageSize" : 753664,
"capped" : false,
"nindexes" : 2,
"totalIndexSize" : 933888,
"indexSizes" : {
"_id_" : 405504,
"id_1" : 528384
},
"ok" : 1
},
"shard2" : {
"ns" : "testdb.table1",
"size" : 1851768,
"count" : 34292,
"avgObjSize" : 54,
"storageSize" : 606208,
"capped" : false,
"nindexes" : 2,
"totalIndexSize" : 774144,
"indexSizes" : {
"_id_" : 335872,
"id_1" : 438272
},
"ok" : 1
},
"shard3" : {
"ns" : "testdb.table1",
"size" : 1171368,
"count" : 21692,
"avgObjSize" : 54,
"storageSize" : 376832,
"capped" : false,
新闻标题：MongoDB之分片
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