标签：mysql主从复制原理
mysql主从复制
mysql支持单向 双向 链式级联 实时 异步复制，在复制过程中，一台服务器充当主服务器（Master）,而一个或多个其他服务器充当从服务器(Slave)
mysql主从复制的应用场景
1、主从服务器互为备份
2、主从服务器读写分离分担网站压力
读写分离
中大型公司：通过程序(php,java)
测试环境：代理软件(mysql-proxy,amoeba)
门户网站：分布式dbproxy（读写分离，hash负载均衡，健康检查）
主从同步实践操作（多实例环境） 1、主库上面设置server-id值并开启binlog参数 [root@centos03 ~]# egrep "log-bin|server-id" /data/3306/my.cnf log-bin = /data/3306/mysql-bin server-id = 1 检查实际配置效果 [root@centos03 ~]# mysql -uroot -p123456 -S /data/3306/mysql.sock -e "show variables like ‘log_bin‘;" +---------------+-------+ | Variable_name | Value | +---------------+-------+ | log_bin | ON | +---------------+-------+ 2、建立用于同步的账号 mysql> grant replication slave on *.* to rep@‘172.16.80.%‘ identified by ‘123456‘; 说明：replication slave 是mysql同步的必须权限，此处不要授权all mysql> flush privileges; 查看授权后的结果 mysql> show grants for rep@‘172.16.80.%‘; +--------------------------------------------------------------------------------------------------------------------------+ | Grants for rep@172.16.80.% | +--------------------------------------------------------------------------------------------------------------------------+ | GRANT REPLICATION SLAVE ON *.* TO ‘rep‘@‘172.16.80.%‘ IDENTIFIED BY PASSWORD ‘*6BB4837EB74329105EE4568DDA7DC67ED2CA2AD9‘ | +--------------------------------------------------------------------------------------------------------------------------+ 1 row in set (0.00 sec) 3、锁表，导出数据库 mysql> flush table with read lock; #该窗口不能断，新开一个窗口做数据库导出操作 Query OK, 0 rows affected (0.00 sec) mysql> show master status; +------------------+----------+--------------+------------------+ | File | Position | Binlog_Do_DB | Binlog_Ignore_DB | +------------------+----------+--------------+------------------+ | mysql-bin.000002 | 332 | | | +------------------+----------+--------------+------------------+ 1 row in set (0.00 sec) [root@centos03 ~]# mysqldump -uroot -p123456 -S /data/3306/mysql.sock -A -B --events --master-data=2 > /opt/rep.sql #导出所有数据库 [root@centos03 ~]# vim /opt/rep.sql -- CHANGE MASTER TO MASTER_LOG_FILE=‘mysql-bin.000002‘, MASTER_LOG_POS=332; #可以看到该语句的记录位置和上面show master status是一样的，注释状态 4、数据库导出后，解锁 mysql> show master status; #再次查看位置点，以验证上面的锁表操作是否有效 +------------------+----------+--------------+------------------+ | File | Position | Binlog_Do_DB | Binlog_Ignore_DB | +------------------+----------+--------------+------------------+ | mysql-bin.000002 | 332 | | | +------------------+----------+--------------+------------------+ 1 row in set (0.00 sec) mysql> unlock tables; Query OK, 0 rows affected (0.00 sec) 5、从库上面 [root@centos03 ~]# egrep "log-bin|server-id" /data/3307/my.cnf #log-bin = /data/3307/mysql-bin #log-bin无需开启 server-id = 3 #server-id的值不能和主库上面的值一样 [root@centos03 ~]# mysql -uroot -p123456 -S /data/3307/mysql.sock < /opt/rep.sql #导入从主库备份的数据库 [root@centos03 ~]# mysql -uroot -phello123 -S /data/3307/mysql.sock mysql> change master to -> master_host=‘172.16.80.118‘, -> master_user=‘rep‘, -> master_password=‘123456‘, -> master_log_file=‘mysql-bin.000002‘, -> master_log_pos=332; Query OK, 0 rows affected (0.03 sec) 验证一下 [root@centos03 ~]# cat /data/3307/data/master.info 18 mysql-bin.000002 332 172.16.80.118 rep 123456 3306 60 0 mysql> start slave; Query OK, 0 rows affected (0.01 sec) mysql> show slave status\G; #观察Slave_IO和Slave_SQL 这两个线程的状态是否是yes *************************** 1. row *************************** Slave_IO_State: Waiting for master to send event Master_Host: 172.16.80.118 Master_User: rep Master_Port: 3306 Connect_Retry: 60 Master_Log_File: mysql-bin.000002 Read_Master_Log_Pos: 332 Relay_Log_File: relay-bin.000002 Relay_Log_Pos: 253 Relay_Master_Log_File: mysql-bin.000002 Slave_IO_Running: Yes Slave_SQL_Running: Yes Replicate_Do_DB: Replicate_Ignore_DB: mysql Replicate_Do_Table: Replicate_Ignore_Table: Replicate_Wild_Do_Table: Replicate_Wild_Ignore_Table: Last_Errno: 0 Last_Error: Skip_Counter: 0 Exec_Master_Log_Pos: 332 Relay_Log_Space: 403 Until_Condition: None Until_Log_File: Until_Log_Pos: 0 Master_SSL_Allowed: No Master_SSL_CA_File: Master_SSL_CA_Path: Master_SSL_Cert: Master_SSL_Cipher: Master_SSL_Key: Seconds_Behind_Master: 0 Master_SSL_Verify_Server_Cert: No Last_IO_Errno: 0 Last_IO_Error: Last_SQL_Errno: 0 Last_SQL_Error: Replicate_Ignore_Server_Ids: Master_Server_Id: 1 1 row in set (0.00 sec)
6、登录主库创建数据库，看是否会同步到从库上面 [root@centos03 ~]# mysql -uroot -p123456 -S /data/3306/mysql.sock mysql> create database martin; Query OK, 1 row affected (0.01 sec) 观察从库，可以看到已经同步过来 mysql> show databases; +--------------------+ | Database | +--------------------+ | information_schema | | martin | | mysql | | performance_schema | | test | +--------------------+ 5 rows in set (0.00 sec) [root@centos03 ~]# cd /data/3307 [root@centos03 3307]# ls data my.cnf mysql mysqld.pid mysql_martin3307.err mysql.sock relay-bin.000001 relay-bin.000002 relay-bin.index relay-log.info [root@centos03 3307]# cat data/master.info 18 mysql-bin.000002 419 172.16.80.118 rep 123456 3306 60 0 [root@centos03 3307]# mysqlbinlog relay-bin.000002 /*!\C utf8 *//*!*/; SET @@session.character_set_client=33,@@session.collation_connection=33,@@session.collation_server=33/*!*/; SET @@session.lc_time_names=0/*!*/; SET @@session.collation_database=DEFAULT/*!*/; create database martin
mysql主从复制原理总结：
1、异步同步方式
2、逻辑同步模式，多种模式，默认是通过sql语句执行
3、主库通过记录bin-log实现对从库的同步，bin-log记录数据库更新的语句
4、主库一个IO线程，从库一个IO线程和一个SQL线程
5、从库关键文件master.info relay-log relay-info
6、如果从库还需要做级联从库，从库需要打开log-bin和log-slave-updates参数
本文出自 “厚德载物” 博客，谢绝转载！
标签：mysql主从复制原理
原文地址：http://huaxin.blog.51cto.com/903026/1841312
