[DataBase] MongoDB (8) 副本集

MongoDB  创建副本集

MongoDB复制是将数据同步在多个服务器的过程。

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。

复制还允许您从硬件故障和服务中断中恢复数据。

1. 建立配置文件

mongodb.conf

  1 # Start MongoDB as a daemon on port 5568
  2
  3 port = 5568
  4 fork = true
  5 replSet = test_replica_set
  6 dbpath = /datatest/db
  7 logpath = /datatest/db/test.log
  8 logappend = true
  9 

mongodb2.conf

  2
  3 port = 5569
  4 fork = true
  5 replSet = test_replica_set
  6 dbpath = /datatest/db2
  7 logpath = /datatest/db/test2.log
  8 logappend = true
  9 

mongodb3.conf

  2
  3 port = 5570
  4 fork = true
  5 replSet = test_replica_set
  6 dbpath = /datatest/db3
  7 logpath = /datatest/db/test.log
  8 logappend = true
  9

2. 启动数据库

mac-abeen:bin abeen$ sudo ./mongod -f mongodb.conf
about to fork child process, waiting until server is ready for connections.
forked process: 37181
child process started successfully, parent exiting
mac-abeen:bin abeen$ sudo ./mongod -f mongodb2.conf
about to fork child process, waiting until server is ready for connections.
forked process: 37185
child process started successfully, parent exiting
mac-abeen:bin abeen$ sudo ./mongod -f mongodb3.conf
about to fork child process, waiting until server is ready for connections.
forked process: 37189
child process started successfully, parent exiting

3. 初始化副本集

mac-abeen:bin abeen$ ./mongo --nodb
MongoDB shell version: 3.2.8
> config = {}
{ }
> config = {"_id": "test_replica_set", "members": [
... {"_id": 0, "host": "localhost:5568"}, {"_id": 1, "host": "localhost:5569"}, {"_id": 2, "host": "localhost:5570"}]}
{
	"_id" : "test_replica_set",
	"members" : [
		{
			"_id" : 0,
			"host" : "localhost:5568"
		},
		{
			"_id" : 1,
			"host" : "localhost:5569"
		},
		{
			"_id" : 2,
			"host" : "localhost:5570"
		}
	]
}
> db = (new Mongo("localhost:5568")).getDB("test")
test
> rs.initiate(config)
{ "ok" : 1 }
test_replica_set:OTHER> 

test_replica_set:PRIMARY> rs.config()
{
	"_id" : "test_replica_set",
	"version" : 1,
	"protocolVersion" : NumberLong(1),
	"members" : [
		{
			"_id" : 0,
			"host" : "localhost:5568",
			"arbiterOnly" : false,
			"buildIndexes" : true,
			"hidden" : false,
			"priority" : 1,
			"tags" : {

			},
			"slaveDelay" : NumberLong(0),
			"votes" : 1
		},
		{
			"_id" : 1,
			"host" : "localhost:5569",
			"arbiterOnly" : false,
			"buildIndexes" : true,
			"hidden" : false,
			"priority" : 1,
			"tags" : {

			},
			"slaveDelay" : NumberLong(0),
			"votes" : 1
		},
		{
			"_id" : 2,
			"host" : "localhost:5570",
			"arbiterOnly" : false,
			"buildIndexes" : true,
			"hidden" : false,
			"priority" : 1,
			"tags" : {

			},
			"slaveDelay" : NumberLong(0),
			"votes" : 1
		}
	],
	"settings" : {
		"chainingAllowed" : true,
		"heartbeatIntervalMillis" : 2000,
		"heartbeatTimeoutSecs" : 10,
		"electionTimeoutMillis" : 10000,
		"getLastErrorModes" : {

		},
		"getLastErrorDefaults" : {
			"w" : 1,
			"wtimeout" : 0
		},
		"replicaSetId" : ObjectId("5850f445c8cacd70496883b0")
	}
}

4. 写入数据并查看副本集数据

test_replica_set:PRIMARY>
test_replica_set:PRIMARY> for (i=0; i < 100; i++){db.coll.insert({"count": i})}
WriteResult({ "nInserted" : 1 })
test_replica_set:PRIMARY> db.coll.count()
100
test_replica_set:PRIMARY> db.coll.find().limit(5)
{ "_id" : ObjectId("5850f5f35f1a7d82c0b45b51"), "count" : 0 }
{ "_id" : ObjectId("5850f5f35f1a7d82c0b45b52"), "count" : 1 }
{ "_id" : ObjectId("5850f5f35f1a7d82c0b45b53"), "count" : 2 }
{ "_id" : ObjectId("5850f5f35f1a7d82c0b45b54"), "count" : 3 }
{ "_id" : ObjectId("5850f5f35f1a7d82c0b45b55"), "count" : 4 }

查看副本集是否有数据
mac-abeen:bin abeen$ ./mongo --port 5569 --host localhost
MongoDB shell version: 3.2.8
connecting to: localhost:5569/test

test_replica_set:SECONDARY> db.coll.find().limit(5)
Error: error: { "ok" : 0, "errmsg" : "not master and slaveOk=false", "code" : 13435 }
设置连接可读取数据
test_replica_set:SECONDARY> db.setSlaveOk()
副本中已有数据
test_replica_set:SECONDARY> db.coll.find().limit(5)
{ "_id" : ObjectId("5850f5f35f1a7d82c0b45b53"), "count" : 2 }
{ "_id" : ObjectId("5850f5f35f1a7d82c0b45b55"), "count" : 4 }
{ "_id" : ObjectId("5850f5f35f1a7d82c0b45b52"), "count" : 1 }
{ "_id" : ObjectId("5850f5f35f1a7d82c0b45b54"), "count" : 3 }
{ "_id" : ObjectId("5850f5f35f1a7d82c0b45b51"), "count" : 0 }