MongoDB 分片的原理、搭建、应用
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因为要放到后台用用配置文件启动，需要修改配置文件：
/etc/mongod_20000.conf
#数据目录
dbpath=/usr/local/config/
#日志文件
logpath=/var/log/mongodb/mongodb_config.log
#日志追加
logappend=true
#端口
port = 20000
#最大连接数
maxConns = 50
pidfilepath = /var/run/mongo_20000.pid
#日志,redo log
journal = true
#刷写提交机制
journalCommitInterval = 200
#守护进程模式
fork = true
#刷写数据到日志的频率
syncdelay = 60
#storageEngine = wiredTiger
#操作日志,单位M
oplogSize = 1000
#命名空间的文件大小,默认16M，最大2G。
nssize = 16
noauth = true
unixSocketPrefix = /tmp
configsvr = true
/etc/mongod_21000.conf
数据目录
dbpath=/usr/local/config1/
#日志文件
logpath=/var/log/mongodb/mongodb_config1.log
#日志追加
logappend=true
#端口
port = 21000
#最大连接数
maxConns = 50
pidfilepath = /var/run/mongo_21000.pid
#日志,redo log
journal = true
#刷写提交机制
journalCommitInterval = 200
#守护进程模式
fork = true
#刷写数据到日志的频率
syncdelay = 60
#storageEngine = wiredTiger
#操作日志,单位M
oplogSize = 1000
#命名空间的文件大小,默认16M，最大2G。
nssize = 16
noauth = true
unixSocketPrefix = /tmp
configsvr = true
开启配置服务器：
root@mongo1:~# mongod -f /etc/mongod_20000.conf
about to fork child process, waiting until server is ready for connections.
forked process: 8545
child process started successfully, parent exiting
root@mongo1:~# mongod -f /etc/mongod_21000.conf
about to fork child process, waiting until server is ready for connections.
forked process: 8595
child process started successfully, parent exiting
同理再起一个22000端口的配置服务器。
#数据目录
dbpath=/usr/local/config2/
#日志文件
logpath=/var/log/mongodb/mongodb_config2.log
#日志追加
logappend=true
#端口
port = 22000
#最大连接数
maxConns = 50
pidfilepath = /var/run/mongo_22000.pid
#日志,redo log
journal = true
#刷写提交机制
journalCommitInterval = 200
#守护进程模式
fork = true
#刷写数据到日志的频率
syncdelay = 60
#storageEngine = wiredTiger
#操作日志,单位M
oplogSize = 1000
#命名空间的文件大小,默认16M，最大2G。
nssize = 16
noauth = true
unixSocketPrefix = /tmp
configsvr = true
View Code
2）路由服务器的启动。(A、B上各开启1个，Port：30000)
路由服务器不保存数据，把日志记录一下即可。
# mongos
#日志文件
logpath=/var/log/mongodb/mongodb_route.log
#日志追加
logappend=true
#端口
port = 30000
#最大连接数
maxConns = 100
#绑定地址
#bind_ip=192.168.200.*,...,
pidfilepath = /var/run/mongo_30000.pid
configdb=192.168.200.A:20000,192.168.200.A:21000,192.168.200.A:22000 #必须是1个或则3个配置 。
#configdb=127.0.0.1:20000 #报错
#守护进程模式 fork = true
其中最重要的参数是
configdb，不能在其后面带的配置服务器的地址写成localhost或则127.0.0.1，需要设置成其他分片也能访问的地址，即192.168.200.A:20000/21000/22000。否则在addshard的时候会报错：
{
"ok" : 0,
"errmsg" : "can‘t use localhost as a shard since all shards need to communicate. either use all shards and configdbs in localhost or all in actual IPs host: 172.16.5.104:20000 isLocalHost:0"
}
开启mongos：
root@mongo1:~# mongos -f /etc/mongod_30000.conf
2015-07-10T14:42:58.741+0800 W SHARDING running with 1 config server should be done only for testing purposes and is not recommended for production
about to fork child process, waiting until server is ready for connections.
forked process: 8965
child process started successfully, parent exiting
3）分片服务器的启动：
就是一个普通的mongod进程：
root@mongo1:~# mongod -f /etc/mongod_40000.conf
note: noprealloc may hurt performance in many applications
about to fork child process, waiting until server is ready for connections.
forked process: 9020
child process started successfully, parent exiting
A服务器上面的服务开启完毕
root@mongo1:~# ps -ef | grep mongo
root 9020 1 0 14:47 ? 00:00:06 mongod -f /etc/mongod_40000.conf
root 9990 1 0 15:14 ? 00:00:02 mongod -f /etc/mongod_20000.conf
root 10004 1 0 15:14 ? 00:00:01 mongod -f /etc/mongod_21000.conf
root 10076 1 0 15:20 ? 00:00:00 mongod -f /etc/mongod_22000.conf
root 10096 1 0 15:20 ? 00:00:00 mongos -f /etc/mongod_30000.conf
按照上面的方法再到B上开启分片服务和路由服务(配置文件一样)，以及在C上开启分片服务。到此分片的配置服务器、路由服务器、分片服务器都已经部署完成。
三、配置分片： 下面的操作都是在mongodb的命令行里执行
1）添加分片：sh.addShard("IP:Port")
登陆路由服务器 mongos 操作 ：
root@mongo1:~# mongo --port=30000
MongoDB shell version: 3.0.4
connecting to: 127.0.0.1:30000/test
mongos>
添加分片：
mongos> sh.status() #查看集群的信息
--- Sharding Status ---
sharding version: {
"_id" : 1,
"minCompatibleVersion" : 5,
"currentVersion" : 6,
"clusterId" : ObjectId("559f72470f93270ba60b26c6")
}
shards:
balancer:
Currently enabled: yes
Currently running: no
Failed balancer rounds in last 5 attempts: 0
Migration Results for the last 24 hours:
No recent migrations
databases:
{ "_id" : "admin", "partitioned" : false, "primary" : "config" }
mongos> sh.addShard("192.168.200.A:40000") #添加分片
{ "shardAdded" : "shard0000", "ok" : 1 }
mongos> sh.addShard("192.168.200.B:40000") #添加分片
{ "shardAdded" : "shard0001", "ok" : 1 }
mongos> sh.addShard("192.168.200.C:40000") #添加分片
{ "shardAdded" : "shard0002", "ok" : 1 }
mongos> sh.status() #查看集群信息
--- Sharding Status ---
sharding version: {
"_id" : 1,
"minCompatibleVersion" : 5,
"currentVersion" : 6,
"clusterId" : ObjectId("559f72470f93270ba60b26c6")
}
shards: #分片信息
{ "_id" : "shard0000", "host" : "192.168.200.A:40000" }
{ "_id" : "shard0001", "host" : "192.168.200.B:40000" }
{ "_id" : "shard0002", "host" : "192.168.200.C:40000" }
balancer:
Currently enabled: yes
Currently running: no
Failed balancer rounds in last 5 attempts: 0
Migration Results for the last 24 hours:
No recent migrations
databases:
{ "_id" : "admin", "partitioned" : false, "primary" : "config" }
2）开启分片功能：sh.enableSharding("库名")、sh.shardCollection("库名.集合名",{"key":1})
mongos> sh.enableSharding("dba") #首先对数据库启用分片
{ "ok" : 1 }
mongos> sh.status() #查看分片信息
--- Sharding Status ---...
...
databases:
{ "_id" : "admin", "partitioned" : false, "primary" : "config" }
{ "_id" : "test", "partitioned" : false, "primary" : "shard0000" }
{ "_id" : "dba", "partitioned" : true, "primary" : "shard0000" }
mongos> sh.shardCollection("dba.account",{"name":1}) #再对集合进行分片，name字段是片键。
{ "collectionsharded" : "dba.account", "ok" : 1 }
mongos> sh.status()
--- Sharding Status ---...
shards:
{ "_id" : "shard0000", "host" : "192.168.200.51:40000" }
{ "_id" : "shard0001", "host" : "192.168.200.52:40000" }
{ "_id" : "shard0002", "host" : "192.168.200.53:40000" }
...
databases:
{ "_id" : "admin", "partitioned" : false, "primary" : "config" }
{ "_id" : "test", "partitioned" : false, "primary" : "shard0000" }
{ "_id" : "dba", "partitioned" : true, "primary" : "shard0000" } #库
dba.account
shard key: { "name" : 1 } #集合
chunks:
shard0000 1
{ "name" : { "$minKey" : 1 } } -->> { "name" : { "$maxKey" : 1 } } on : shard0000 Timestamp(1, 0)
上面加粗部分表示分片信息已经配置完成。
四、测试 ： 对dba库的account集合进行测试，随机写入，查看是否分散到3个分片中。
通过一个python脚本进行随机写入：分别向A、B 2个mongos各写入10万条记录。
#!/usr/bin/env python
#-*- coding:utf-8 -*-
#随即写MongoDB Shard 测试
import pymongo
import time
from random import Random
def random_str(randomlength=8):
str = ‘‘
chars = ‘AaBbCcDdEeFfGgHhIiJjKkLlMmNnOoPpQqRrSsTtUuVvWwXxYyZz0123456789‘
length = len(chars) - 1
random = Random()
for i in range(randomlength):
str+=chars[random.randint(0, length)]
return str
def inc_data(conn):
db = conn.dba
# db = conn.test
collection = db.account
for i in range(100000):
str = ‘‘
chars = ‘AaBbCcDdEeFfGgHhIiJjKkLlMmNnOoPpQqRrSsTtUuVvWwXxYyZz0123456789‘
length = len(chars) - 1
random = Random()
for i in range(15):
str+=chars[random.randint(0, length)]
string = str
collection.insert({"name" : string, "age" : 123+i, "address" : "hangzhou"+string})
if __name__ ==‘__main__‘:
conn = pymongo.MongoClient(host=‘192.168.200.A/B‘,port=30000)
StartTime = time.time()
print "===============$inc==============="
print "StartTime : %s" %StartTime
inc_data(conn)
EndTime = time.time()
print "EndTime : %s" %EndTime
CostTime = round(EndTime-StartTime)
print "CostTime : %s" %CostTime
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查看是否分片：db.collection.stats()
mongos> db.account.stats() #查看集合的分布情况
...
...
"shards" : {
"shard0000" : {
"ns" : "dba.account",
"count" : 89710,
"size" : 10047520,
...
...
"shard0001" : {
"ns" : "dba.account",
"count" : 19273,
"size" : 2158576,
...
...
"shard0002" : {
"ns" : "dba.account",
"count" : 91017,
"size" : 10193904,
...
...
上面加粗部分为集合的基本信息，可以看到分片成功，各个分片都有数据(count)。到此MongoDB分片集群搭建成功。
++++++++++++++++++++++++++++++++++++++++++++++++
感兴趣的同学可以看下面这个比较有趣的现象：
#在写之前分片的基本信息：
mongos> sh.status()
--- Sharding Status ---
...
...
databases:
{ "_id" : "admin", "partitioned" : false, "primary" : "config" }
{ "_id" : "test", "partitioned" : false, "primary" : "shard0000" }
{ "_id" : "dba", "partitioned" : true, "primary" : "shard0000" }
dba.account
shard key: { "name" : 1 }
chunks:
shard0000 1
{ "name" : { "$minKey" : 1 } } -->> { "name" : { "$maxKey" : 1 } } on : shard0000 Timestamp(1, 0) #可以看到这里片键的写入，都是写在shard0000里面的。
#在写期间的分片基本信息：
mongos> sh.status()
--- Sharding Status ---
...
...
databases:
{ "_id" : "admin", "partitioned" : false, "primary" : "config" }
{ "_id" : "test", "partitioned" : false, "primary" : "shard0000" }
{ "_id" : "dba", "partitioned" : true, "primary" : "shard0000" }
dba.account
shard key: { "name" : 1 }
chunks: #数据块分布
shard0000 1
shard0001 1
shard0002 1
{ "name" : { "$minKey" : 1 } } -->> { "name" : "5yyfY8mmR5HyhGJ" } on : shard0001 Timestamp(2, 0)
{ "name" : "5yyfY8mmR5HyhGJ" } -->> { "name" : "woQAv99Pq1FVoMX" } on : shard0002 Timestamp(3, 0)
{ "name" : "woQAv99Pq1FVoMX" } -->> { "name" : { "$maxKey" : 1 } } on : shard0000 Timestamp(3, 1) #可以看到片键写入的基本分布
#在写完成后的基本信息：
mongos> sh.status()
--- Sharding Status ---
...
...
databases:
{ "_id" : "admin", "partitioned" : false, "primary" : "config" }
{ "_id" : "test", "partitioned" : false, "primary" : "shard0000" }
{ "_id" : "dba", "partitioned" : true, "primary" : "shard0000" }
dba.account
shard key: { "name" : 1 }
chunks: #数据块分布
shard0000 2
shard0001 1
shard0002 2
{ "name" : { "$minKey" : 1 } } -->> { "name" : "5yyfY8mmR5HyhGJ" } on : shard0001 Timestamp(2, 0)
{ "name" : "5yyfY8mmR5HyhGJ" } -->> { "name" : "UavMbMlfszZOFrz" } on : shard0000 Timestamp(4, 0)
{ "name" : "UavMbMlfszZOFrz" } -->> { "name" : "t9LyVSNXDmf6esP" } on : shard0002 Timestamp(4, 1)
{ "name" : "t9LyVSNXDmf6esP" } -->> { "name" : "woQAv99Pq1FVoMX" } on : shard0002 Timestamp(3, 4)
{ "name" : "woQAv99Pq1FVoMX" } -->> { "name" : { "$maxKey" : 1 } } on : shard0000 Timestamp(3,