mysql主从服务（主从从结构）
下午的126分钟开始：
删除所有数据库，只保留系统库
53服务器操作：
[root@host53 mysql]# pwd
/var/lib/mysql
[root@host53 mysql]# systemctl stop mysqld.service
[root@host53 mysql]# rm -rf master.info relay-log.info
[root@host53 mysql]# rm -rf host53-relay-bin.*
[root@host53 mysql]# systemctl start mysqld
52 服务器操作：
[root@host52 mysql]# pwd
/var/lib/mysql
[root@host52 mysql]# systemctl stop mysqld
[root@host52 mysql]# rm -rf master.info relay-log.info
[root@host52 mysql]# rm -rf host52-relay-bin.*
[root@host52 mysql]# systemctl start mysqld
[root@host52 mysql]# mysql -uroot -p ——为了保证数据的一致性，把多于的数据库删除，只保留系统库
mysql> drop database gamedb;
Query OK, 1 row affected (0.15 sec)
51服务器操作：
oot@host51 mysql]# systemctl stop mysqld.service
[root@host51 mysql]# rm -rf master51.*
[root@host51 mysql]# ls
auto.cnf gamedb ib_buffer_pool ibdata1 ib_logfile0 ib_logfile1 mysql performance_schema xtrabackup_info
[root@host51 mysql]# rm -rf gamedb/ ——删除库的文件就相当于把库给删了
[root@host51 mysql]# systemctl restart mysqld
135分钟哦
52.是从库也是主库
53:
[root@host53 ~]# systemctl stop mysqld
[root@host53 ~]# vim /etc/my.cnf
[mysqld]
server_id=53
:wq
[root@host53 ~]# systemctl start mysqld
[root@host53 ~]# mysql -h192.168.4.52 -uyaya -p123qqq...A
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
+--------------------+
4 rows in set (0.00 sec)
mysql> show slave status;
Empty set (0.00 sec)
mysql> change master to
-> master_host="192.168.4.52",
-> master_user="yaya",
-> master_password="123qqq...A",
-> master_log_file="master52.000001",
-> master_log_pos=154;
Query OK, 0 rows affected, 2 warnings (0.31 sec)
mysql> start slave;
Query OK, 0 rows affected (0.01 sec)
mysql> show slave status\G;
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.4.52
Master_User: yaya
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: master52.000001
Read_Master_Log_Pos: 154
Relay_Log_File: host53-relay-bin.000002
Relay_Log_Pos: 319
Relay_Master_Log_File: master52.000001
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
为共享数据创建数据：
在51数据库操作：
mysql> create database gamedb;
Query OK, 1 row affected (0.04 sec)
mysql> create table gamedb.a(id int);
Query OK, 0 rows affected (0.27 sec)
mysql> grant select,insert on gamedb.* to testuser@"%" identified by "123qqq...A";
Query OK, 0 rows affected, 1 warning (0.03 sec)
什么原因：
mysql> show master status;
+-----------------+----------+--------------+------------------+-------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+-----------------+----------+--------------+------------------+-------------------+
| master52.000001 | 154 | | | |
+-----------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)
[root@host52 mysql]# mysqlbinlog master52.000001 | grep -insert
5:#180720 16:14:44 server id 52 end_log_pos 123 CRC32 0xbb198393 Start: binlog v 4, server v 5.7.17-log created 180720 16:14:44 at startup
[mysqld]
log_slave_updates
server_id=52
log-bin=master52
binlog_format="mixed
mysql> show slave status\G;
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.4.52
Master_User: yaya
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: master52.000002
Read_Master_Log_Pos: 720
Relay_Log_File: host53-relay-bin.000004
Relay_Log_Pos: 365
Relay_Master_Log_File: master52.000002
Slave_IO_Running: Yes
Slave_SQL_Running: No
Last_Error: Error 'Table 'gamedb.a' doesn't exist' on query. Default database: 'gamedb'. Query: 'insert into a values(6663)'
报错信息：开了集连，生产环境下应该先开集连
解决方案：
mysql> stop slave;
Query OK, 0 rows affected (0.01 sec)
mysql> create database gamedb;
Query OK, 1 row affected (0.00 sec)
mysql> use gamedb;
Database changed
mysql> create table a(id int);
Query OK, 0 rows affected (0.16 sec)
mysql> start slave;
Query OK, 0 rows affected (0.09 sec)
mysql> select * from a;
+------+
| id |
+------+
| 6663 |
| 6663 |
+------+
2 rows in set (0.00 sec)
主主结构（互为主从）
不能同时给客户端insert update 的权限，有可能出现冲突
一般跟第三方软件做高可用集群