MySQL主主复制及相关的排坑
主主复制的本质就是2台MySQL服务器互为主从。
但如此配置极易产生问题，如数据不一致导致主键的冲突，以及一些其他的错误。
为了减少主键冲突的情况，可以考虑让两个节点的id分别使用技术和偶数，这就需要用到两个服务器选项来配置。
auto_increment_offset #设置id的开始点
auto_increment_increment #设置id的步进主主复制工作中不推荐使用，如确实需要使用，也将其当为主从来使用。
主主复制的搭建
使用2台主机来配置主主复制
| 主机 | ip |
|---|---|
| Master1 | 192.168.73.110 |
| Master2 | 192.168.73.111 |
配置Master1
1.修改配置文件
[root@Master1 ~]# vim /etc/my.cnf
[mysqld]
log-bin
server-id=1
auto_increment_offset=1
auto_increment_increment=22.启动MySQL服务
[root@Master1 ~]# systemctl start mariadb3.查看二进制日志位置
[root@Master1 ~]# mysql -e "SHOW MASTER LOGS;"
+--------------------+-----------+
| Log_name | File_size |
+--------------------+-----------+
| mariadb-bin.000001 | 245 |
+--------------------+-----------+4.创建一个用来复制数据的用户
[root@Master1 ~]# mysql -e "GRANT REPLICATION SLAVE ON *.* TO 'repluser'@'192.168.73.%' IDENTIFIED BY 'centos';"配置Master2为Master1的从节点
1.修改配置文件
[root@Master2 ~]# vim /etc/my.cnf
[mysqld]
log-bin
server-id=2
auto_increment_offset=1
auto_increment_increment=22.设置CHANGE MASTER TO
MariaDB [(none)]> CHANGE MASTER TO MASTER_HOST='192.168.73.110', MASTER_USER='repluser',MASTER_PASSWORD='centos',MASTER_PORT=3306,MASTER_LOG_FILE='mariadb-bin.000001',MASTER_LOG_POS=245;
Query OK, 0 rows affected (0.01 sec)3.查看从节点状态，确认无误
MariaDB [(none)]> SHOW SLAVE STATUS\G;
*************************** 1. row ***************************
Slave_IO_State:
Master_Host: 192.168.73.110
Master_User: repluser
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mariadb-bin.000001
Read_Master_Log_Pos: 245
Relay_Log_File: mariadb-relay-bin.000001
Relay_Log_Pos: 4
Relay_Master_Log_File: mariadb-bin.000001
Slave_IO_Running: No
Slave_SQL_Running: No4.启动线程
MariaDB [(none)]> START SLAVE;
Query OK, 0 rows affected (0.01 sec)5.再次查看从节点状态
MariaDB [(none)]> SHOW SLAVE STATUS\G;
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.73.110
Master_User: repluser
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mariadb-bin.000001
Read_Master_Log_Pos: 407
Relay_Log_File: mariadb-relay-bin.000002
Relay_Log_Pos: 693
Relay_Master_Log_File: mariadb-bin.000001
Slave_IO_Running: Yes
Slave_SQL_Running: Yes #线程已经全部启动6.查看二进制日志位置
查看二级制日志位置用于，给Master1作为从节点使用。由于Master2上无数据二进制日志为干净日志，所以可以直接供Master1使用。
MariaDB [(none)]> SHOW MASTER LOGS;
+--------------------+-----------+
| Log_name | File_size |
+--------------------+-----------+
| mariadb-bin.000001 | 245 |
+--------------------+-----------+
1 row in set (0.00 sec)配置Master1为Master2的从节点
1.输入CHANGE MASTER TO的信息
CHANGE MASTER TO MASTER_HOST='192.168.73.111', MASTER_USER='repluser',MASTER_PASSWORD='centos',MASTER_PORT=3306,MASTER_LOG_FILE='mariadb-bin.000001',MASTER_LOG_POS=245;2.查看从状态,确认信息无误
MariaDB [(none)]> SHOW SLAVE STATUS\G;
*************************** 1. row ***************************
Slave_IO_State:
Master_Host: 192.168.73.111
Master_User: repluser
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mariadb-bin.000001
Read_Master_Log_Pos: 245
Relay_Log_File: mariadb-relay-bin.000001
Relay_Log_Pos: 4
Relay_Master_Log_File: mariadb-bin.000001
Slave_IO_Running: No
Slave_SQL_Running: No3.启动线程
MariaDB [(none)]> START SLAVE;
Query OK, 0 rows affected (0.01 sec)4.再次查看slave status
MariaDB [(none)]> SHOW SLAVE STATUS\G;
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.73.111
Master_User: repluser
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mariadb-bin.000001
Read_Master_Log_Pos: 245
Relay_Log_File: mariadb-relay-bin.000002
Relay_Log_Pos: 531
Relay_Master_Log_File: mariadb-bin.000001
Slave_IO_Running: Yes
Slave_SQL_Running: Yes主主复制搭建完毕
测试
测试一、查看Master1输入数据，Master2能否复制
1.从Master1上导入hellodb数据库
[root@Master1 ~]# mysql -e "SHOW DATABASES;"
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| test |
+--------------------+
[root@Master1 ~]# mysql < hellodb_innodb.sql
[root@Master1 ~]# mysql -e "SHOW DATABASES;"
+--------------------+
| Database |
+--------------------+
| information_schema |
| hellodb |
| mysql |
| performance_schema |
| test |
+--------------------+2.从节点上查看数据库
[root@Master2 ~]# mysql -e "SHOW DATABASES;"
+--------------------+
| Database |
+--------------------+
| information_schema |
| hellodb |
| mysql |
| performance_schema |
| test |
+--------------------+测试二、Master2插入数据查看Master1是否能复制
1.在Master2中插入条记录
[root@Master2 ~]# mysql -e "INSERT hellodb.teachers(name,age) VALUE ('Ye Fan','25');"
[root@Master2 ~]# mysql -e "INSERT hellodb.teachers(name,age) VALUE ('Shi Hao','20');"
[root@Master2 ~]# mysql -e "SELECT * FROM hellodb.teachers"
+-----+---------------+-----+--------+
| TID | Name | Age | Gender |
+-----+---------------+-----+--------+
| 1 | Song Jiang | 45 | M |
| 2 | Zhang Sanfeng | 94 | M |
| 3 | Miejue Shitai | 77 | F |
| 4 | Lin Chaoying | 93 | F |
| 5 | Ye Fan | 25 | NULL |
| 7 | Shi Hao | 20 | NULL | #此处可以看到插入数据时主键tid是以2为步进递增的。
+-----+---------------+-----+--------+2.在Master1上查看数据
[root@Master1 ~]# mysql -e "SELECT * FROM hellodb.teachers;"
+-----+---------------+-----+--------+
| TID | Name | Age | Gender |
+-----+---------------+-----+--------+
| 1 | Song Jiang | 45 | M |
| 2 | Zhang Sanfeng | 94 | M |
| 3 | Miejue Shitai | 77 | F |
| 4 | Lin Chaoying | 93 | F |
| 5 | Ye Fan | 25 | NULL |
| 7 | Shi Hao | 20 | NULL |
+-----+---------------+-----+--------+测试三、两边同时创建一张相同的表
1.同时对两个主机做出创建表的操作
2.查看Master1的hellodb库
[root@Master1 ~]# mysql -e "SHOW TABLES FROM hellodb"
+-------------------+
| Tables_in_hellodb |
+-------------------+
| classes |
| coc |
| courses |
| scores |
| students |
| teachers |
| test |
| toc |
+-------------------+3.查看Master2的hellodb库
[root@Master2 ~]# mysql -e "SHOW TABLES FROM hellodb"
+-------------------+
| Tables_in_hellodb |
+-------------------+
| classes |
| coc |
| courses |
| scores |
| students |
| teachers |
| test |
| toc |
+-------------------+此处看上好像没问提
测试四、继续插入数据,从看看复制状况
1.在Master1上继续往hellodb.test表中插入数据
[root@Master1 ~]# mysql -e "INSERT hellodb.test VALUE(1,'Tang San');"2.Master2上查看复制状况
[root@Master2 ~]# mysql
MariaDB [(none)]> SELECT * FROM hellodb.test;
Empty set (0.00 sec)
#没有复制到数据查错
分别查看Master1和Master2主机上的SLAVE STATUS;
Master1状态
MariaDB [(none)]> SHOW SLAVE STATUS\G;
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.73.111
Master_User: repluser
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mariadb-bin.000001
Read_Master_Log_Pos: 871
Relay_Log_File: mariadb-relay-bin.000002
Relay_Log_Pos: 1018
Relay_Master_Log_File: mariadb-bin.000001
Slave_IO_Running: Yes
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: 1050
Last_Error: Error 'Table 'test' already exists' on query. Default database: ''. Query: 'CREATE TABLE hellodb.test(id int auto_increment primary key,name char(20))'
Skip_Counter: 0
Exec_Master_Log_Pos: 732
Relay_Log_Space: 1453
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: 1050
Last_SQL_Error: Error 'Table 'test' already exists' on query. Default database: ''. Query: 'CREATE TABLE hellodb.test(id int auto_increment primary key,name char(20))'
Replicate_Ignore_Server_Ids:
Master_Server_Id: 2
1 row in set (0.00 sec)
ERROR: No query specifiedMaster2状态
MariaDB [(none)]> SHOW SLAVE STATUS\G;
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.73.110
Master_User: repluser
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mariadb-bin.000001
Read_Master_Log_Pos: 8360
Relay_Log_File: mariadb-relay-bin.000002
Relay_Log_Pos: 8308
Relay_Master_Log_File: mariadb-bin.000001
Slave_IO_Running: Yes
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: 1050
Last_Error: Error 'Table 'test' already exists' on query. Default database: ''. Query: 'CREATE TABLE hellodb.test(id int auto_increment primary key,name char(20))'
Skip_Counter: 0
Exec_Master_Log_Pos: 8022
Relay_Log_Space: 8942
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: 1050
Last_SQL_Error: Error 'Table 'test' already exists' on query. Default database: ''. Query: 'CREATE TABLE hellodb.test(id int auto_increment primary key,name char(20))'
Replicate_Ignore_Server_Ids:
Master_Server_Id: 1
1 row in set (0.00 sec)
ERROR: No query specified
显示出来刚在在创建表时已经复制出错，由于两边同时创建了同一张表发生了冲突
排错
分别在主从节点上停止线程
MariaDB [(none)]> STOP SLAVE;分别在主从节点上使用sql_slave_skip_counter忽略错误
MariaDB [(none)]> SET GLOBAL sql_slave_skip_counter=1;分别在主从节点上再次启动线程
MariaDB [(none)]> START SLAVE;再次在从节点上查test表
[root@Master2 ~]# mysql -e "SELECT * FROM hellodb.test;"
+----+----------+
| id | name |
+----+----------+
| 1 | Tang San |
+----+----------+此时数据已经能正常复制过去