mysql主从目录
1.mysql主从复制数据原理
- 主库将所有的写操作记录在bin-log日志中，并生成一个bin dump线程将bin-log日志传输给从库的I/O进程。
- 从库生成两个线程，一个I/O，一个SQL线程
- I/O线程器请求主库的bin-log，并将得到的bin-log日志写入relaylog（中继日志）文件中
- SQL线程，会读取relay log文件中的日志，并解析成具体操作，来实现主从的操作一致，达到最终数据一致的目的
2. mysql安装
分别在主从两台服务器上安装mysql服务
3.mysql主从配置
3.1 确保从数据库与主数据库里的数据一样
为确保从数据库与主数据库里的数据一样，先全备主数据库并还原到从数据库中
//先查看主库有哪些库
[root@localhost ~]# mysql -uroot -pwangqing123! -e 'show databases;'
mysql: [Warning] Using a password on the command line interface can be insecure.
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| student |
| sys |
| teacher |
+--------------------+
//再查看从库有哪些库
[root@localhost ~]# mysql -uroot -pwangqing123! -e 'show databases;'
mysql: [Warning] Using a password on the command line interface can be insecure.
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
+--------------------+
//全备主库
//全备主库时需要另开一个终端，给数据库加上读锁，避免在备份期间有其他人在写入导致数据不一致
mysql> FLUSH TABLES WITH READ LOCK;
Query OK, 0 rows affected (0.00 sec)
//此锁表的终端必须在备份完成以后才能退出
//备份主库并将备份文件传送到从库
[root@localhost ~]# mysqldump -uroot -pwangqing123! --all-databases > /opt/all-201808191200.sql
mysqldump: [Warning] Using a password on the command line interface can be insecure.
[root@localhost ~]# ls /opt/
all-201808191200.sql
[root@localhost ~]# scp /opt/all-201808191200.sql [email protected]:/opt/
[email protected]'s password:
all-201808191200.sql 100% 786KB 10.6MB/s 00:00
//解除主库的锁表状态，直接退出交互式界面即可
mysql> quit
Bye
//在从库上恢复主库的备份并查看从库有哪些库，确保与主库一致
[root@localhost ~]# mysql -uroot -pwangqing123! < /opt/all-201808191200.sql
mysql: [Warning] Using a password on the command line interface can be insecure.
[root@localhost ~]# mysql -uroot -pwangqing123! -e 'show databases;'
mysql: [Warning] Using a password on the command line interface can be insecure.
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| student |
| sys |
| teacher |
+--------------------+
3.2 在主数据库里创建一个同步账号授权给从数据库使用
mysql> CREATE USER 'repl'@'172.16.12.129' IDENTIFIED BY 'repl123';
Query OK, 0 rows affected (0.00 sec)
mysql> GRANT REPLICATION SLAVE ON *.* TO 'repl'@'172.16.12.129';
Query OK, 0 rows affected (0.00 sec)
mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)
3.3 配置主数据库
[root@localhost ~]# vim /etc/my.cnf
//在[mysqld]这段的后面加上如下内容
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
log-bin=mysql-bin //启用binlog日志
server-id=1 //数据库服务器唯一标识符，主库的server-id值必须比从库的大
symbolic-links=0
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
//重启mysql服务
[root@localhost ~]# systemctl restart mysqld
[root@localhost ~]# ss -antl
State Recv-Q Send-Q Local Address:Port Peer Address:Port
LISTEN 0 128 *:22 *:*
LISTEN 0 100 127.0.0.1:25 *:*
LISTEN 0 128 :::22 :::*
LISTEN 0 100 ::1:25 :::*
LISTEN 0 80 :::3306 :::*
//查看主库的状态
mysql> show master status;
+------------------+----------+--------------+------------------+-------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+------------------+----------+--------------+------------------+-------------------+
| mysql-bin.000001 | 154 | | | |
+------------------+----------+--------------+------------------+-------------------+
1 row in set (0.01 sec)
3.4 配置从数据库
[root@localhost ~]# vim /etc/my.cnf
//添加如下内容
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
server-id=2 //设置从库的唯一标识符，从库的server-id值必须小于主库的该值
relay-log=mysql-relay-bin //启用中继日志relay-log
symbolic-links=0
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
//重启从库的mysql服务
[root@localhost ~]# systemctl restart mysqld
[root@localhost ~]# ss -antl
State Recv-Q Send-Q Local Address:Port Peer Address:Port
LISTEN 0 128 *:22 *:*
LISTEN 0 100 127.0.0.1:25 *:*
LISTEN 0 128 :::22 :::*
LISTEN 0 100 ::1:25 :::*
LISTEN 0 80 :::3306 :::*
//配置并启动主从复制
mysql> CHANGE MASTER TO
-> MASTER_HOST='172.16.12.128',
-> MASTER_USER='repl',
-> MASTER_PASSWORD='repl123',
-> MASTER_LOG_FILE='mysql-bin.000001',
-> MASTER_LOG_POS=154;
Query OK, 0 rows affected, 2 warnings (0.33 sec)
mysql> start slave;
Query OK, 0 rows affected (0.01 sec)
//查看从服务器状态
mysql> show slave status \G
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 172.16.12.128
Master_User: repl
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-bin.000001
Read_Master_Log_Pos: 154
Relay_Log_File: mysql-relay-bin.000002
Relay_Log_Pos: 320
Relay_Master_Log_File: mysql-bin.000001
Slave_IO_Running: Yes //此处必须为Yes
Slave_SQL_Running: Yes //此处必须为Yes
Replicate_Do_DB:
Replicate_Ignore_DB:
3.5 测试验证
在主服务器的student库的bj2表中插入数据：
mysql> select * from bj2;
Empty set (0.00 sec)
mysql> insert into bj2 values (1,'sean',20),(2,'tom',23),(3,'jerry',30);
Query OK, 3 rows affected (0.00 sec)
Records: 3 Duplicates: 0 Warnings: 0
mysql> select * from bj2;
+----+-------+------+
| id | name | age |
+----+-------+------+
| 1 | sean | 20 |
| 2 | tom | 23 |
| 3 | jerry | 30 |
+----+-------+------+
3 rows in set (0.00 sec)
在从数据库中查看数据是否同步：
mysql> use student;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Database changed
mysql> select * from bj2;
+----+-------+------+
| id | name | age |
+----+-------+------+
| 1 | sean | 20 |
| 2 | tom | 23 |
| 3 | jerry | 30 |
+----+-------+------+
3 rows in set (0.00 sec)
