所有的关系型数据库都存在一个通病性能差，在企业中如果用户量特别打，将所有的数据都存放在一台服务器上，其性能时远远达不到要求的。所以需要使用一些手段来解决其性能的问题。
提升性能的方式有向上扩展以及向外扩展
向上扩展(Scale Up):使用更新更好的硬件，但硬件在怎么更新也有其性能的极限。盲目的向上扩展无法结局根本的问题
向外扩展(Scale Out):就是使用多台机器分摊压力来提供服务
主从复制就是拿多个数据库服务器，组合成一个服务器的集合对外共同服务实现性能的提升，逻辑上使用的时对外扩展的方式(Scale out)来提升服务器的性能。
| 服务器类型 | ip地址 |
|---|---|
| 主 | 192.168.73.133 |
| 从 | 192.168.73.145 |
1.在主服务器上启用二进制日志
[root@localhost ~]# vim /etc/mysql/my.cnf
log-bin=/data/bin/mysql-bin
binlog-format=row
server-id=12.创建二进制日志目录
[root@localhost ~]# mkdir /data/bin
[root@localhost ~]# chown -R mysql.mysql /data/bin3.重启服务
[root@localhost ~]# service mysqld restart
Restarting mysqld (via systemctl): [ OK ]4.创建一个用来让从服务器复制数据的账号
MariaDB [(none)]> GRANT REPLICATION SLAVE ON *.* TO repluser@‘192.168.73.%‘ IDENTIFIED BY ‘centos‘;
Query OK, 0 rows affected (0.00 sec)
5.查看主服务器正在使用的二进制日志
MariaDB [(none)]> SHOW MASTER LOGS;
+------------------+-----------+
| Log_name | File_size |
+------------------+-----------+
| mysql-bin.000001 | 515 | #当前二进制文件及位置需要记录，从服务器设置时需要
+------------------+-----------+
1 row in set (0.00 sec)1.修改配置文件
server-id = 2 #server-id改为和主服务器不同
read-only #设置为只读
#log-bin=mysql-bin #将二进制日志关闭2.启动MySQL服务器
[root@localhost ~]# service mysqld restart
Starting mysqld (via systemctl): [ OK ]3.关联主服务器
MariaDB [(none)]> CHANGE MASTER TO MASTER_HOST=‘192.168.73.133‘,MASTER_USER=‘repluser‘,MASTER_PASSWORD=‘centos‘,MASTER_PORT=3306,MASTER_LOG_FILE=‘mysql-bin.000001‘,MASTER_LOG_POS=515;
Query OK, 0 rows affected (0.01 sec)4.查看从服务器状态
MariaDB [(none)]> SHOW SLAVE STATUS\G;
*************************** 1. row ***************************
Slave_IO_State:
Master_Host: 192.168.73.133
Master_User: repluser
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-bin.000001
Read_Master_Log_Pos: 515
Relay_Log_File: localhost-relay-bin.000001
Relay_Log_Pos: 4
Relay_Master_Log_File: mysql-bin.000001
Slave_IO_Running: No
Slave_SQL_Running: No
Replicate_Do_DB:
Replicate_Ignore_DB:
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: 515
Relay_Log_Space: 256
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: NULL
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: 0
Master_SSL_Crl:
Master_SSL_Crlpath:
Using_Gtid: No
Gtid_IO_Pos:
Replicate_Do_Domain_Ids:
Replicate_Ignore_Domain_Ids:
Parallel_Mode: conservative
SQL_Delay: 0
SQL_Remaining_Delay: NULL
Slave_SQL_Running_State:
1 row in set (0.00 sec)
ERROR: No query specified
5.启动线程
MariaDB [(none)]> START SLAVE;
Query OK, 0 rows affected (0.00 sec)在主服务器上导入一个hellodb数据库
[root@localhost ~]# mysql < hellodb_innodb.sql 从服务器上查看是否同步成功
MariaDB [(none)]> SHOW DATABASES;
+--------------------+
| Database |
+--------------------+
| hellodb | #已经有hellodb库
| information_schema |
| mysql |
| performance_schema |
| test |
+--------------------+
5 rows in set (0.00 sec)| 拥有一台已经有数据的mysql服务器，追加一台从服务器 |
服务器 | IP地址 |
|---|---|---|
| Master | 192.168.73.148 | |
| Slave | 192.168.73.149 |
Master中的数据
[root@localhost ~]# mysql -e "SHOW DATABASES;"
+--------------------+
| Database |
+--------------------+
| information_schema |
| hellodb |
| mysql |
| performance_schema |
| test |
| test1 |
+--------------------+1.修改主服务器配置文件
[root@localhost ~]# vim /etc/my.cnf
[mysqld]
log-bin=/data/bin/mysql-bin
binlog-format=row
[root@localhost ~]# systemctl restart mariadb
2.创建复制账号
[root@localhost ~]# mysql -e "GRANT REPLICATION SLAVE ON *.* TO ‘repluser‘@‘192.168.73.%‘ IDENTIFIED BY ‘centos‘;"3.备份主节点中的所有数据
[root@localhost ~]# mysqldump -A --single-transaction -F --master-data=1 > /data/all.sql
[root@localhost ~]# vim /data/all.sql4.将备份数据传送给从节点
[root@localhost ~]# scp /data/all.sql 192.168.73.149:/data1.修改配置文件
[root@localhost ~]# vim /etc/my.cnf
[mysqld]
server-id=2
read-only2.清空MySQL数据库
[root@localhost ~]# rm -rf /var/lib/mysql/*3.修改备份数据将chang master to 加入文件中
CHANGE MASTER TO
MASTER_HOST=‘192.168.73.148‘,
MASTER_USER=‘repluser‘,
MASTER_PASSWORD=‘centos‘,
MASTER_PORT=3306,
MASTER_LOG_FILE=‘mysql-bin.000005‘,
MASTER_LOG_POS=245;4.启动MySQL服务，并导入备份
[root@localhost ~]# mysql < /data/all.sql 5.查看从节点状态
MariaDB [(none)]> SHOW SLAVE STATUS\G;
*************************** 1. row ***************************
Slave_IO_State:
Master_Host: 192.168.73.148
Master_User: repluser
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-bin.000005
Read_Master_Log_Pos: 245
Relay_Log_File: mariadb-relay-bin.000001
Relay_Log_Pos: 4
Relay_Master_Log_File: mysql-bin.000005
Slave_IO_Running: No
Slave_SQL_Running: No
Replicate_Do_DB:
Replicate_Ignore_DB:
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: 245
Relay_Log_Space: 245
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: NULL
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: 0
1 row in set (0.00 sec)
6.启动线程
MariaDB [(none)]> START SLAVE;
Query OK, 0 rows affected (0.00 sec)7.再次查看从节点状态，复制的2个线程已经启动
MariaDB [(none)]> SHOW SLAVE STATUS\G;
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.73.148
Master_User: repluser
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-bin.000005
Read_Master_Log_Pos: 245
Relay_Log_File: mariadb-relay-bin.000002
Relay_Log_Pos: 529
Relay_Master_Log_File: mysql-bin.000005
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
Replicate_Do_DB:
Replicate_Ignore_DB:
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: 245
Relay_Log_Space: 825
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)主节点删test1库
MariaDB [(none)]> DROP DATABASE test1;
Query OK, 1 row affected (0.01 sec)从节点查看是否同步
MariaDB [(none)]> SHOW DATABASES;
+--------------------+
| Database |
+--------------------+
| information_schema |
| hellodb |
| mysql |
| performance_schema |
| test |
+--------------------+
5 rows in set (0.00 sec) #已经没有test1库原文：https://blog.51cto.com/11886307/2390636