Mycat的简单使用（二）

  • 主从读写分离
  • 双主双从读写分离
    • 原理
    • 配置数据库
      • 删除上述db1、db2释放压力
      • 创建四个配置文件
      • 配置Master1(M1)
      • 配置Slave1(S1)
      • 创建Master2(M2)配置文件并创建数据库
      • 创建Slave2(S2)配置文件并创建数据库
      • 在两台主机上建立主从复制账户
      • 在从机上配置需要复制的主机
      • 配置两个主机相互备份
      • 验证mysql主从复制
    • 配置mycat读写分离
    • 验证双主切换

主从读写分离

分别向主数据库 和从数据库 插入不一样的数据
在mycat客户端查询数据，发现都是写数据库的内容
修改Mycat的配置文件schema.xml的节点的balance属性

1. 当balance=0 时，不开启读写分离，所有读操作都发生在当前的writeHost上
2. 当balance=1 ，所有读操作都随机发送到当前的writeHost对应的readHost和备用的writeHos都参与select语句的负载均衡，简单的说当双主双从模式（M1->S1 ,M2-S2 M2和M2互为主备）
3. 当balance=2，所有的读操作都随机发送到所有的writeHost,readHost上
4. 当balance=3 ，所有的读操作都只发送到writeHost(db1)的readHost(db2)上

生产当中应该使用 1或者3，此处为了演示切换的效果设置balance="2"

<?xml version="1.0"?>
<!DOCTYPE mycat:schema SYSTEM "schema.dtd">
<mycat:schema xmlns:mycat="http://io.mycat/"><schema name="TESTDB" checkSQLschema="false" sqlMaxLimit="100" dataNode="dn1"></schema><dataNode name="dn1" dataHost="host1" database="testdb" /><dataHost name="host1" maxCon="1000" minCon="10" balance="2"writeType="0" dbType="mysql" dbDriver="native" switchType="1"  slaveThreshold="100"><heartbeat>select user()</heartbeat><!--can have multi write hosts --><writeHost host="hostM1" url="172.17.0.2:3306" user="root"   password="123456"><!-- can have multi read hosts --><readHost host="hostS1" url="172.17.0.3:3306" user="root" password="123456" /></writeHost></dataHost></mycat:schema>

使用客户端连接mycat查询数据

[root@mycat ~]# mysql -umycat -p123456 -h 127.0.0.1 -P 8066
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MySQL connection id is 4
Server version: 5.6.29-mycat-1.6-RELEASE-20161028204710 MyCat Server (OpenCloundDB)Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.MySQL [(none)]> use TESTDB
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -ADatabase changed
MySQL [TESTDB]> select * from test_table;
+----+--------------+
| id | name         |
+----+--------------+
|  1 | 订单信息     |
|  2 | 读机器       |
+----+--------------+
2 rows in set (0.01 sec)MySQL [TESTDB]> select * from test_table;
+----+--------------+
| id | name         |
+----+--------------+
|  1 | 订单信息     |
|  2 | 读机器       |
+----+--------------+
2 rows in set (0.01 sec)MySQL [TESTDB]> select * from test_table;
+----+--------------+
| id | name         |
+----+--------------+
|  1 | 订单信息     |
|  2 | 读机器       |
+----+--------------+
2 rows in set (0.00 sec)MySQL [TESTDB]> select * from test_table;
+----+--------------+
| id | name         |
+----+--------------+
|  1 | 订单信息     |
|  2 | 读机器       |
+----+--------------+
2 rows in set (0.00 sec)

双主双从读写分离

原理

一个主机ml用于处理所有写请求，它的从机s1和另一台主机m2还有它的从机s2负责所有读请
求。当m1主机宕机后，m2主机负责写请求，ml、m2互为备机。架构图如下。

配置数据库

此处重新准备数据库,使用docker安装如下四个mysql容器(可以删除db1、db2两个容器以释放虚拟机压力)

序号 角色 容器名 ip地址 server-id(my.cnf)
1 Master1 m1 172.17.0.2 1
2 Slave1 s1 172.17.0.3 2
3 Master2 m2 172.17.0.4 3
4 Slave s2 172.17.0.5 4

删除上述db1、db2释放压力

[root@mycat ~]# docker stop db1  && docker rm db1 && docker stop db2  && docker rm db2
db1
db1
db2
db2
[root@mycat ~]#

创建四个配置文件

创建配置文件目录：

#创建配置文件
[root@mycat ~]# mkdir -p /root/dbcnf#创建四个配置文件
[root@mycat ~]# touch /root/dbcnf/master1.cnf
[root@mycat ~]# touch /root/dbcnf/master2.cnf
[root@mycat ~]# touch /root/dbcnf/slave1.cnf
[root@mycat ~]# touch /root/dbcnf/slave2.cnf
[root@mycat ~]#

配置Master1(M1)

修改/root/dbcnf/master1.cnf配置文件添加如下配置：

[mysqld]
#主服务器唯一ID
server-id=1
#启用二进制日志
log-bin=mysql-bin
# 设置不要复制的数据库(可设置多个)
binlog-ignore-db=mysql
binlog-ignore-db=information_schema
#设置需要复制的数据库
binlog-do-db=testdb
#设置logbin格式
binlog_format=STATEMENT
# 在作为从数据库的时候，有写入操作也要更新二进制日志文件
log-slave-updates
#表示自增长字段每次递增的量，指自增字段的起始值，其默认值是1，取值范围是1 .. 65535
auto-increment-increment=2
# 表示自增长字段从哪个数开始，指字段一次递增多少，他的取值范围是1 .. 65535
auto-increment-offset=1

使用上述文件创建容器：

[root@mycat ~]# docker run --name m1 -p 3316:3306 -v /root/dbcnf/master1.cnf:/etc/mysql/my.cnf -e MYSQL_ROOT_PASSWORD=123456 -d mysql:5.7
ace8d2729df2f7084c277fba06d18c17725d21a08c5eed6c676c7f890075523f
[root@mycat ~]# docker ps
CONTAINER ID   IMAGE       COMMAND                  CREATED         STATUS         PORTS                                                  NAMES
ace8d2729df2   mysql:5.7   "docker-entrypoint.s…"   5 seconds ago   Up 4 seconds   33060/tcp, 0.0.0.0:3316->3306/tcp, :::3316->3306/tcp   m1
[root@mycat ~]# docker inspect --format '{{ .NetworkSettings.IPAddress }}'  m1
172.17.0.2
[root@mycat ~]#

通过docker命令查看到m1容器的ip地址为172.17.0.2,填入上述准备的表格中

关于mysql中部分配置的说明：
1、关于log-slave-updates()
从库开启log-bin参数，如果直接往从库写数据，是可以记录log-bin日志的，但是从库通过I0线程读取主库二进制日志文件，然后通过SQL线程写入的数据，是不会记录binlog日志的。也就是说从库从主库上复制的数据，是不写入从库的binlog日志的。所以从库做为其他从库的主库时需要在配置文件中添加log-slave-updates参数。
2、关于binlog-format
mysql复制主要有三种方式：
基于SQL语句的复制(statement-based replication, SBR)，
基于行的复制(row-based replication, RBR)，
混合模式复制(mixed-based replication, MBR)。对应的，
binlog的格式也有三种：STATEMENT，ROW，MIXED。
① STATEMENT模式（SBR）
每一条会修改数据的sql语句会记录到binlog中。优点是并不需要记录每一条sql语句和每一行的数据变化，减少了binlog日志量，节约IO，提高性能。缺点是在某些情况下会导致master-slave中的数据不一致(如sleep()函数， last_insert_id()，以及user-defined functions(udf)等会出现问题)
② ROW模式（RBR）
不记录每条sql语句的上下文信息，仅需记录哪条数据被修改了，修改成什么样了。而且不会出现某些特定情况下的存储过程、或function、或trigger的调用和触发无法被正确复制的问题。缺点是会产生大量的日志，尤其是alter table的时候会让日志暴涨。
③ MIXED模式（MBR）
以上两种模式的混合使用，一般的复制使用STATEMENT模式保存binlog，对于STATEMENT模式无法复制的操作使用ROW模式保存binlog，MySQL会根据执行的SQL语句选择日志保存方式。

配置Slave1(S1)

保持原配置/root/dbcnf/slave1.cnf不动即可

[mysqld]#从服务器唯一ID
server-id=2
#启用中继日志
relay-log=mysql-relay

使用上述文件创建容器并查看ip

[root@mycat ~]# vi /root/dbcnf/slave1.cnf [root@mycat ~]# docker run --name s1 -p 3326:3306 -v /root/dbcnf/slave1.cnf:/etc/mysql/my.cnf -e MYSQL_ROOT_PASSWORD=123456 -d mysql:5.7
78f1f8ce6c8b1d6d4216ac2de432a95b39fee99c3bd689d1326bb9399a255d8c[root@mycat ~]# docker ps
CONTAINER ID   IMAGE       COMMAND                  CREATED          STATUS          PORTS                                                  NAMES
78f1f8ce6c8b   mysql:5.7   "docker-entrypoint.s…"   5 seconds ago    Up 3 seconds    33060/tcp, 0.0.0.0:3326->3306/tcp, :::3326->3306/tcp   s1
ace8d2729df2   mysql:5.7   "docker-entrypoint.s…"   12 minutes ago   Up 12 minutes   33060/tcp, 0.0.0.0:3316->3306/tcp, :::3316->3306/tcp   m1[root@mycat ~]# docker inspect --format '{{ .NetworkSettings.IPAddress }}'  s1
172.17.0.3
[root@mycat ~]#

创建Master2(M2)配置文件并创建数据库

创建/root/dbcnf/master2.cnf配置文件并添加如下配置：
同Master1相似,需要修改server-id(为3)、和auto_increment_offset配置

[mysqld]
#主服务器唯一ID
server-id=3
#启用二进制日志
log-bin=mysql-bin
# 设置不要复制的数据库(可设置多个)
binlog-ignore-db=mysql
binlog-ignore-db=information_schema
#设置需要复制的数据库
binlog-do-db=testdb
#设置logbin格式
binlog_format=STATEMENT
# 在作为从数据库的时候，有写入操作也要更新二进制日志文件
log-slave-updates
#表示自增长字段每次递增的量，指自增字段的起始值，其默认值是1，取值范围是1 .. 65535
auto-increment-increment=2
# 表示自增长字段从哪个数开始，指字段一次递增多少，他的取值范围是1 .. 65535
auto-increment-offset=2

使用上述文件创建容器并查看ip

[root@mycat ~]# vi /root/dbcnf/master2.cnf[root@mycat ~]# docker run --name m2 -p 3336:3306 -v /root/dbcnf/master2.cnf:/etc/mysql/my.cnf -e MYSQL_ROOT_PASSWORD=123456 -d mysql:5.7
d567f78b546e63eecf172b36d648f31868632b632fbad230b570d812078459f8[root@mycat ~]# docker ps
CONTAINER ID   IMAGE       COMMAND                  CREATED          STATUS          PORTS                                                  NAMES
d567f78b546e   mysql:5.7   "docker-entrypoint.s…"   9 seconds ago    Up 4 seconds    33060/tcp, 0.0.0.0:3336->3306/tcp, :::3336->3306/tcp   m2
78f1f8ce6c8b   mysql:5.7   "docker-entrypoint.s…"   4 minutes ago    Up 3 minutes    33060/tcp, 0.0.0.0:3326->3306/tcp, :::3326->3306/tcp   s1
ace8d2729df2   mysql:5.7   "docker-entrypoint.s…"   16 minutes ago   Up 16 minutes   33060/tcp, 0.0.0.0:3316->3306/tcp, :::3316->3306/tcp   m1[root@mycat ~]# docker inspect --format '{{ .NetworkSettings.IPAddress }}'  m2
172.17.0.4[root@mycat ~]#

创建Slave2(S2)配置文件并创建数据库

创建/root/dbcnf/slave2.cnf配置文件并添加如下配置(同Slave1一样即可),修改server-id

[mysqld]#从服务器唯一ID
server-id=4
#启用中继日志
relay-log=mysql-relay

使用上述文件创建容器并查看ip

[root@mycat ~]# vim /root/dbcnf/slave2.cnf [root@mycat ~]# docker run --name s2 -p 3346:3306 -v /root/dbcnf/slave2.cnf:/etc/mysql/my.cnf -e MYSQL_ROOT_PASSWORD=123456 -d mysql:5.7
f2706a827e15c2443e4056793a9b58370e528148d279546edc677a833a6611fb[root@mycat ~]# docker ps
CONTAINER ID   IMAGE       COMMAND                  CREATED          STATUS          PORTS                                                  NAMES
f2706a827e15   mysql:5.7   "docker-entrypoint.s…"   5 seconds ago    Up 2 seconds    33060/tcp, 0.0.0.0:3346->3306/tcp, :::3346->3306/tcp   s2
d567f78b546e   mysql:5.7   "docker-entrypoint.s…"   8 minutes ago    Up 8 minutes    33060/tcp, 0.0.0.0:3336->3306/tcp, :::3336->3306/tcp   m2
78f1f8ce6c8b   mysql:5.7   "docker-entrypoint.s…"   12 minutes ago   Up 12 minutes   33060/tcp, 0.0.0.0:3326->3306/tcp, :::3326->3306/tcp   s1
ace8d2729df2   mysql:5.7   "docker-entrypoint.s…"   24 minutes ago   Up 24 minutes   33060/tcp, 0.0.0.0:3316->3306/tcp, :::3316->3306/tcp   m1[root@mycat ~]# docker inspect --format '{{ .NetworkSettings.IPAddress }}'  s2
172.17.0.5
[root@mycat ~]#

至此，四台mysql机器（实际是容器）的环境信息如下：

序号 角色 容器名 容器id ip地址 server-id(my.cnf) 启用二进制日志 启用中继日志
1 Master1 m1 ace8d2729df2 172.17.0.2 1 是
2 Slave1 s1 78f1f8ce6c8b 172.17.0.3 2 是
3 Master2 m2 6b3868d2f49d 172.17.0.4 3 是
4 Slave s2 d99c2936a62d 172.17.0.5 4 是

在两台主机上建立主从复制账户

在两个mysql主机上（M1、M2）建立帐户并授权。CREATE USER 'slave'@'%' IDENTIFIED BY '123456'; GRANT REPLICATION SLAVE, REPLICATION CLIENT ON *.* TO 'slave'@'%';

具体操作如下:

mysql客户端登录连接m1(IP:172.17.0.2)创建slave用户,并查询master状态

[root@mycat ~]# mysql -uroot -p123456 -h 172.17.0.2 -P3306
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.7.34-log MySQL Community Server (GPL)Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.MySQL [(none)]> CREATE USER 'slave'@'%' IDENTIFIED BY '123456';
Query OK, 0 rows affected (0.00 sec)MySQL [(none)]> GRANT REPLICATION SLAVE, REPLICATION CLIENT ON *.* TO 'slave'@'%';
Query OK, 0 rows affected (0.01 sec)MySQL [(none)]> show master status;
+------------------+----------+--------------+--------------------------+-------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB         | Executed_Gtid_Set |
+------------------+----------+--------------+--------------------------+-------------------+
| mysql-bin.000003 |      619 | testdb       | mysql,information_schema |                   |
+------------------+----------+--------------+--------------------------+-------------------+
1 row in set (0.00 sec)MySQL [(none)]>

mysql客户端登录连接m2(ip:172.17.0.4)创建slave用户,并查询master状态

[root@mycat ~]# mysql -uroot -p123456 -h 172.17.0.4 -P3306
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.7.34-log MySQL Community Server (GPL)Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.MySQL [(none)]> CREATE USER 'slave'@'%' IDENTIFIED BY '123456';
Query OK, 0 rows affected (0.06 sec)MySQL [(none)]> GRANT REPLICATION SLAVE, REPLICATION CLIENT ON *.* TO 'slave'@'%';
Query OK, 0 rows affected (0.01 sec)MySQL [(none)]> show master status;
+------------------+----------+--------------+--------------------------+-------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB         | Executed_Gtid_Set |
+------------------+----------+--------------+--------------------------+-------------------+
| mysql-bin.000003 |      619 | testdb       | mysql,information_schema |                   |
+------------------+----------+--------------+--------------------------+-------------------+
1 row in set (0.00 sec)MySQL [(none)]>

配置完两个Master后通过查询可以知道Log_File和Log_POS的值为下述内容。

序号 角色 容器名 容器id ip地址 server-id(my.cnf) 启用二进制日志 启用中继日志 MASTER_LOG_FILE MASTER_LOG_POS
1 Master1 m1 ace8d2729df2 172.17.0.2 1 是 是 mysql-bin.000003 619
2 Slave1 s1 78f1f8ce6c8b 172.17.0.3 2 是
3 Master2 m2 6b3868d2f49d 172.17.0.4 3 是 mysql-bin.000003 619
4 Slave s2 d99c2936a62d 172.17.0.5 4 是

分别记录下File和Position的值后,执行完此步骤后不要再操作主服务器MySQL，防止主服务器状态值变化

在从机上配置需要复制的主机

Slave1(s1) 复制 Master1(m1)，Slave2(s2) 复制 Master2(m2)
CHANGE MASTER TO MASTER_HOST='主机的IP地址', MASTER_USER='slave', MASTER_PASSWORD='123123', MASTER_LOG_FILE='mysql-bin.具体数字',MASTER_LOG_POS=具体值;

进入Slave1(s1)执行 复制主机的命令,并启动从机的slave功能

CHANGE MASTER TO MASTER_HOST='172.17.0.2', MASTER_USER='slave', MASTER_PASSWORD='123456', MASTER_LOG_FILE='mysql-bin.000003',MASTER_LOG_POS=619;

[root@mycat ~]# mysql -uroot -p123456 -h172.17.0.3 -P3306
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.7.34 MySQL Community Server (GPL)Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.MySQL [(none)]> CHANGE MASTER TO MASTER_HOST='172.17.0.2',-> MASTER_USER='slave',-> MASTER_PASSWORD='123456',-> MASTER_LOG_FILE='mysql-bin.000003',MASTER_LOG_POS=619;
Query OK, 0 rows affected, 2 warnings (0.04 sec)MySQL [(none)]> start slave;
Query OK, 0 rows affected (0.00 sec)MySQL [(none)]> show slave status\G;
*************************** 1. row ***************************Slave_IO_State: Waiting for master to send eventMaster_Host: 172.17.0.2Master_User: slaveMaster_Port: 3306Connect_Retry: 60Master_Log_File: mysql-bin.000003Read_Master_Log_Pos: 619Relay_Log_File: mysql-relay.000002Relay_Log_Pos: 320Relay_Master_Log_File: mysql-bin.000003Slave_IO_Running: YesSlave_SQL_Running: YesReplicate_Do_DB: Replicate_Ignore_DB: Replicate_Do_Table: Replicate_Ignore_Table: Replicate_Wild_Do_Table: Replicate_Wild_Ignore_Table: Last_Errno: 0Last_Error: Skip_Counter: 0Exec_Master_Log_Pos: 619Relay_Log_Space: 523Until_Condition: NoneUntil_Log_File: Until_Log_Pos: 0Master_SSL_Allowed: NoMaster_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: NoLast_IO_Errno: 0Last_IO_Error: Last_SQL_Errno: 0Last_SQL_Error: Replicate_Ignore_Server_Ids: Master_Server_Id: 1Master_UUID: 306d7a6c-cf33-11eb-8ea3-0242ac110002Master_Info_File: /var/lib/mysql/master.infoSQL_Delay: 0SQL_Remaining_Delay: NULLSlave_SQL_Running_State: Slave has read all relay log; waiting for more updatesMaster_Retry_Count: 86400Master_Bind: Last_IO_Error_Timestamp: Last_SQL_Error_Timestamp: Master_SSL_Crl: Master_SSL_Crlpath: Retrieved_Gtid_Set: Executed_Gtid_Set: Auto_Position: 0Replicate_Rewrite_DB: Channel_Name: Master_TLS_Version:
1 row in set (0.00 sec)ERROR: No query specifiedMySQL [(none)]>

进入Slave2(s2)执行 复制主机的命令,并启动从机的slave功能

复制的是M2（IP：172.17.0.4）
CHANGE MASTER TO MASTER_HOST='172.17.0.4', MASTER_USER='slave', MASTER_PASSWORD='123456', MASTER_LOG_FILE='mysql-bin.000003',MASTER_LOG_POS=619;

[root@mycat ~]# mysql -uroot -p123456 -h172.17.0.5 -P3306
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.7.34 MySQL Community Server (GPL)Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.MySQL [(none)]> CHANGE MASTER TO MASTER_HOST='172.17.0.4',-> MASTER_USER='slave',-> MASTER_PASSWORD='123456',-> MASTER_LOG_FILE='mysql-bin.000003',MASTER_LOG_POS=619;
Query OK, 0 rows affected, 2 warnings (0.05 sec)MySQL [(none)]> start slave;
Query OK, 0 rows affected (0.00 sec)MySQL [(none)]> show slave status\G;
*************************** 1. row ***************************Slave_IO_State: Waiting for master to send eventMaster_Host: 172.17.0.4Master_User: slaveMaster_Port: 3306Connect_Retry: 60Master_Log_File: mysql-bin.000003Read_Master_Log_Pos: 619Relay_Log_File: mysql-relay.000002Relay_Log_Pos: 320Relay_Master_Log_File: mysql-bin.000003Slave_IO_Running: YesSlave_SQL_Running: YesReplicate_Do_DB: Replicate_Ignore_DB: Replicate_Do_Table: Replicate_Ignore_Table: Replicate_Wild_Do_Table: Replicate_Wild_Ignore_Table: Last_Errno: 0Last_Error: Skip_Counter: 0Exec_Master_Log_Pos: 619Relay_Log_Space: 523Until_Condition: NoneUntil_Log_File: Until_Log_Pos: 0Master_SSL_Allowed: NoMaster_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: NoLast_IO_Errno: 0Last_IO_Error: Last_SQL_Errno: 0Last_SQL_Error: Replicate_Ignore_Server_Ids: Master_Server_Id: 3Master_UUID: 687b8bda-cf38-11eb-956e-0242ac110004Master_Info_File: /var/lib/mysql/master.infoSQL_Delay: 0SQL_Remaining_Delay: NULLSlave_SQL_Running_State: Slave has read all relay log; waiting for more updatesMaster_Retry_Count: 86400Master_Bind: Last_IO_Error_Timestamp: Last_SQL_Error_Timestamp: Master_SSL_Crl: Master_SSL_Crlpath: Retrieved_Gtid_Set: Executed_Gtid_Set: Auto_Position: 0Replicate_Rewrite_DB: Channel_Name: Master_TLS_Version:
1 row in set (0.00 sec)ERROR: No query specifiedMySQL [(none)]>

Slave_IO_Running、Slave_SQL_Running两个参数都是Yes，则说明主从配置成功！
如果显示Connecting可以再执行一次show slave status\G;

配置两个主机相互备份

Master2(db3) 复制 Master1(db1)，Master1(db1) 复制 Master2(db3) 步骤如下：
1、在Master1中配置配置复制命令
2、启动Master1的主从复制功能
3、查看Master1的slave状态
4、在Master2中配置配置复制命令
5、启动Master2的主从复制功能
6、查看Master2的slave状态

具体执行过程如下：
在Master1（IP：172.17.0.2）中配置配置复制命令,复制Master2（IP：172.17.0.4）

[root@mycat ~]# mysql -uroot -p123456 -h172.17.0.2 -P3306
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MySQL connection id is 4
Server version: 5.7.34-log MySQL Community Server (GPL)Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.MySQL [(none)]> CHANGE MASTER TO MASTER_HOST='172.17.0.4',-> MASTER_USER='slave',-> MASTER_PASSWORD='123456',-> MASTER_LOG_FILE='mysql-bin.000003',MASTER_LOG_POS=619;
Query OK, 0 rows affected, 2 warnings (0.04 sec)MySQL [(none)]> start slave;
Query OK, 0 rows affected (0.00 sec)MySQL [(none)]> show slave status\G;
*************************** 1. row ***************************Slave_IO_State: Waiting for master to send eventMaster_Host: 172.17.0.4Master_User: slaveMaster_Port: 3306Connect_Retry: 60Master_Log_File: mysql-bin.000003Read_Master_Log_Pos: 619Relay_Log_File: ace8d2729df2-relay-bin.000002Relay_Log_Pos: 320Relay_Master_Log_File: mysql-bin.000003Slave_IO_Running: YesSlave_SQL_Running: YesReplicate_Do_DB: Replicate_Ignore_DB: Replicate_Do_Table: Replicate_Ignore_Table: Replicate_Wild_Do_Table: Replicate_Wild_Ignore_Table: Last_Errno: 0Last_Error: Skip_Counter: 0Exec_Master_Log_Pos: 619Relay_Log_Space: 534Until_Condition: NoneUntil_Log_File: Until_Log_Pos: 0Master_SSL_Allowed: NoMaster_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: NoLast_IO_Errno: 0Last_IO_Error: Last_SQL_Errno: 0Last_SQL_Error: Replicate_Ignore_Server_Ids: Master_Server_Id: 3Master_UUID: 687b8bda-cf38-11eb-956e-0242ac110004Master_Info_File: /var/lib/mysql/master.infoSQL_Delay: 0SQL_Remaining_Delay: NULLSlave_SQL_Running_State: Slave has read all relay log; waiting for more updatesMaster_Retry_Count: 86400Master_Bind: Last_IO_Error_Timestamp: Last_SQL_Error_Timestamp: Master_SSL_Crl: Master_SSL_Crlpath: Retrieved_Gtid_Set: Executed_Gtid_Set: Auto_Position: 0Replicate_Rewrite_DB: Channel_Name: Master_TLS_Version:
1 row in set (0.00 sec)ERROR: No query specified

在Master2（IP：172.17.0.4）中配置配置复制命令,复制Master1（IP：172.17.0.2）

[root@mycat ~]# mysql -uroot -p123456 -h172.17.0.4 -P3306
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MySQL connection id is 5
Server version: 5.7.34-log MySQL Community Server (GPL)Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.MySQL [(none)]> CHANGE MASTER TO MASTER_HOST='172.17.0.2',-> MASTER_USER='slave',-> MASTER_PASSWORD='123456',-> MASTER_LOG_FILE='mysql-bin.000003',MASTER_LOG_POS=619;
Query OK, 0 rows affected, 2 warnings (0.03 sec)MySQL [(none)]> start slave;
Query OK, 0 rows affected (0.00 sec)MySQL [(none)]> show slave status\G;
*************************** 1. row ***************************Slave_IO_State: Waiting for master to send eventMaster_Host: 172.17.0.2Master_User: slaveMaster_Port: 3306Connect_Retry: 60Master_Log_File: mysql-bin.000003Read_Master_Log_Pos: 619Relay_Log_File: 6b3868d2f49d-relay-bin.000002Relay_Log_Pos: 320Relay_Master_Log_File: mysql-bin.000003Slave_IO_Running: YesSlave_SQL_Running: YesReplicate_Do_DB: Replicate_Ignore_DB: Replicate_Do_Table: Replicate_Ignore_Table: Replicate_Wild_Do_Table: Replicate_Wild_Ignore_Table: Last_Errno: 0Last_Error: Skip_Counter: 0Exec_Master_Log_Pos: 619Relay_Log_Space: 534Until_Condition: NoneUntil_Log_File: Until_Log_Pos: 0Master_SSL_Allowed: NoMaster_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: NoLast_IO_Errno: 0Last_IO_Error: Last_SQL_Errno: 0Last_SQL_Error: Replicate_Ignore_Server_Ids: Master_Server_Id: 1Master_UUID: 306d7a6c-cf33-11eb-8ea3-0242ac110002Master_Info_File: /var/lib/mysql/master.infoSQL_Delay: 0SQL_Remaining_Delay: NULLSlave_SQL_Running_State: Slave has read all relay log; waiting for more updatesMaster_Retry_Count: 86400Master_Bind: Last_IO_Error_Timestamp: Last_SQL_Error_Timestamp: Master_SSL_Crl: Master_SSL_Crlpath: Retrieved_Gtid_Set: Executed_Gtid_Set: Auto_Position: 0Replicate_Rewrite_DB: Channel_Name: Master_TLS_Version:
1 row in set (0.00 sec)ERROR: No query specifiedMySQL [(none)]>

验证mysql主从复制

使用mysql客户端分别连接m1、s1、m2、s2，在M1中创建数据库create database testdb,在s1、m2、s2中查询数据库是否正常同步。

配置mycat读写分离

修改<dataHost>的balance属性，通过此属性配置读写分离的类型
修改 Mycat 的配置文件schema.xml,在原有基础上增加writeHost以及对应的readHost

<?xml version="1.0"?>
<!DOCTYPE mycat:schema SYSTEM "schema.dtd">
<mycat:schema xmlns:mycat="http://io.mycat/"><schema name="TESTDB" checkSQLschema="false" sqlMaxLimit="100" dataNode="dn1"></schema><dataNode name="dn1" dataHost="host1" database="testdb" /><dataHost name="host1" maxCon="1000" minCon="10" balance="1" writeType="0" dbType="mysql" dbDriver="native" switchType="1"  slaveThreshold="100" ><heartbeat>select 1</heartbeat><!-- can have multi write hosts --><writeHost host="hostM1" url="172.17.0.2:3306" user="root" password="123456"><!-- can have multi read hosts --><readHost host="hostS1" url="172.17.0.3:3306" user="root"  password="123456" /></writeHost><writeHost host="hostM2" url="172.17.0.4:3306" user="root" password="123456"><!-- can have multi read hosts --><readHost host="hostS2" url="172.17.0.5:3306" user="root"  password="123456" /></writeHost></dataHost></mycat:schema>

  • balance=“1”: 全部的readHost与stand by writeHost参与select语句的负载均衡。

  • writeType=“0”: 所有写操作发送到配置的第一个writeHost，第一个挂了切到还生存的第二个

  • writeType=“1”，所有写操作都随机的发送到配置的 writeHost，1.5 以后废弃不推荐

  • writeHost，重新启动后以切换后的为准，切换记录在配置文件中:dnindex.properties 。

  • switchType="1"

    • 1默认值，自动切换。
    • -1 表示不自动切换
    • 2 基于 MySQL 主从同步的状态决定是否切换。

操作1
登录mycat创建数据库，成功后登录m1、s1、m2、s2查看表use testdb;,show tables;
可以看到四个数据库都出现了表结构,说明在mycat下主从复制可以用


通过docker ps 或 docker ps|awk '{print $1," ",$13}' 命令可以查看到四个容器对应的容器id（容器内部的主机名即为容器id）

操作2
在mycat中插入能区分的数据，比如插入时带着主机名字的变量,然后查询数据,发现数据库中主机名字在M2、S1、S2之间切换,说明读写分离生效

[root@mycat ~]# mysql -umycat -p123456 -h127.0.0.1 -P8066
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MySQL connection id is 4
Server version: 5.6.29-mycat-1.6-RELEASE-20161028204710 MyCat Server (OpenCloundDB)Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.MySQL [(none)]> use TESTDB
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -ADatabase changed
MySQL [TESTDB]> INSERT INTO user_info(NAME) VALUES(@@hostname);
Query OK, 1 row affected, 1 warning (0.01 sec)MySQL [TESTDB]> select * from user_info;
+----+--------------+
| id | name         |
+----+--------------+
| 11 | 78f1f8ce6c8b |
+----+--------------+
1 row in set (0.00 sec)MySQL [TESTDB]> select * from user_info;
+----+--------------+
| id | name         |
+----+--------------+
| 11 | 6b3868d2f49d |
+----+--------------+
1 row in set (0.00 sec)MySQL [TESTDB]> select * from user_info;
+----+--------------+
| id | name         |
+----+--------------+
| 11 | 78f1f8ce6c8b |
+----+--------------+
1 row in set (0.00 sec)MySQL [TESTDB]> select * from user_info;
+----+--------------+
| id | name         |
+----+--------------+
| 11 | 78f1f8ce6c8b |
+----+--------------+
1 row in set (0.01 sec)MySQL [TESTDB]> select * from user_info;
+----+--------------+
| id | name         |
+----+--------------+
| 11 | d99c2936a62d |
+----+--------------+
1 row in set (0.01 sec)MySQL [TESTDB]> select * from user_info;
+----+--------------+
| id | name         |
+----+--------------+
| 11 | 78f1f8ce6c8b |
+----+--------------+
1 row in set (0.01 sec)MySQL [TESTDB]> select * from user_info;
+----+--------------+
| id | name         |
+----+--------------+
| 11 | 78f1f8ce6c8b |
+----+--------------+
1 row in set (0.00 sec)MySQL [TESTDB]> select * from user_info;
+----+--------------+
| id | name         |
+----+--------------+
| 11 | 78f1f8ce6c8b |
+----+--------------+
1 row in set (0.00 sec)MySQL [TESTDB]> select * from user_info;
+----+--------------+
| id | name         |
+----+--------------+
| 11 | 6b3868d2f49d |
+----+--------------+
1 row in set (0.00 sec)MySQL [TESTDB]> select * from user_info;
+----+--------------+
| id | name         |
+----+--------------+
| 11 | d99c2936a62d |
+----+--------------+
1 row in set (0.00 sec)

验证双主切换

模拟Master1（M1）异常（此处可以停止mysql服务或者停止容器）,测试mycat能否自动切换到Master2正常插入。实现高可用性。


停止m1容器

root@mycat ~]# docker ps
CONTAINER ID   IMAGE       COMMAND                  CREATED       STATUS       PORTS                                                  NAMES
d99c2936a62d   mysql:5.7   "docker-entrypoint.s…"   3 hours ago   Up 3 hours   33060/tcp, 0.0.0.0:3346->3306/tcp, :::3346->3306/tcp   s2
6b3868d2f49d   mysql:5.7   "docker-entrypoint.s…"   3 hours ago   Up 3 hours   33060/tcp, 0.0.0.0:3336->3306/tcp, :::3336->3306/tcp   m2
78f1f8ce6c8b   mysql:5.7   "docker-entrypoint.s…"   3 hours ago   Up 3 hours   33060/tcp, 0.0.0.0:3326->3306/tcp, :::3326->3306/tcp   s1
ace8d2729df2   mysql:5.7   "docker-entrypoint.s…"   4 hours ago   Up 4 hours   33060/tcp, 0.0.0.0:3316->3306/tcp, :::3316->3306/tcp   m1
[root@mycat ~]# docker stop m1
m1
[root@mycat ~]# docker ps
CONTAINER ID   IMAGE       COMMAND                  CREATED       STATUS       PORTS                                                  NAMES
d99c2936a62d   mysql:5.7   "docker-entrypoint.s…"   3 hours ago   Up 3 hours   33060/tcp, 0.0.0.0:3346->3306/tcp, :::3346->3306/tcp   s2
6b3868d2f49d   mysql:5.7   "docker-entrypoint.s…"   3 hours ago   Up 3 hours   33060/tcp, 0.0.0.0:3336->3306/tcp, :::3336->3306/tcp   m2
78f1f8ce6c8b   mysql:5.7   "docker-entrypoint.s…"   3 hours ago   Up 3 hours   33060/tcp, 0.0.0.0:3326->3306/tcp, :::3326->3306/tcp   s1
[root@mycat ~]#

插入数据,并查询

[root@mycat ~]# mysql -umycat -p123456 -h127.0.0.1 -P8066
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MySQL connection id is 6
Server version: 5.6.29-mycat-1.6-RELEASE-20161028204710 MyCat Server (OpenCloundDB)Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.MySQL [(none)]> use TESTDB
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -ADatabase changed
MySQL [TESTDB]> INSERT INTO user_info(NAME) VALUES(concat('valid-switch--',@@hostname));
Query OK, 1 row affected, 1 warning (0.01 sec)MySQL [TESTDB]> select * from user_info;
+----+----------------------------+
| id | name                       |
+----+----------------------------+
| 11 | d99c2936a62d               |
| 12 | valid-switch--d99c2936a62d |
+----+----------------------------+
2 rows in set (0.01 sec)MySQL [TESTDB]> select * from user_info;
+----+----------------------------+
| id | name                       |
+----+----------------------------+
| 11 | d99c2936a62d               |
| 12 | valid-switch--d99c2936a62d |
+----+----------------------------+
2 rows in set (0.00 sec)MySQL [TESTDB]> select * from user_info;
+----+----------------------------+
| id | name                       |
+----+----------------------------+
| 11 | d99c2936a62d               |
| 12 | valid-switch--d99c2936a62d |
+----+----------------------------+
2 rows in set (0.00 sec)

通过实验发现插入操作成功，且查询时能访问到M2对应的S2的机器(如上图所示)
此时重新启动M1后登录Mycat查询数据，发现查询的内容是Master1、Salve1、Salve2其中Master1变为备份主机了。

[root@mycat ~]# mysql -umycat -p123456 -h127.0.0.1 -P8066
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MySQL connection id is 7
Server version: 5.6.29-mycat-1.6-RELEASE-20161028204710 MyCat Server (OpenCloundDB)Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.MySQL [(none)]> use TESTDB
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -ADatabase changed
MySQL [TESTDB]> select * from user_info;
+----+----------------------------+
| id | name                       |
+----+----------------------------+
| 11 | d99c2936a62d               |
| 12 | valid-switch--d99c2936a62d |
+----+----------------------------+
2 rows in set (0.00 sec)MySQL [TESTDB]> select * from user_info;
+----+--------------+
| id | name         |
+----+--------------+
| 11 | 78f1f8ce6c8b |
+----+--------------+
1 row in set (0.01 sec)MySQL [TESTDB]> select * from user_info;
+----+----------------------------+
| id | name                       |
+----+----------------------------+
| 11 | d99c2936a62d               |
| 12 | valid-switch--d99c2936a62d |
+----+----------------------------+
2 rows in set (0.01 sec)MySQL [TESTDB]> select * from user_info;
+----+--------------+
| id | name         |
+----+--------------+
| 11 | 78f1f8ce6c8b |
+----+--------------+
1 row in set (0.00 sec)MySQL [TESTDB]> select * from user_info;
+----+----------------------------+
| id | name                       |
+----+----------------------------+
| 11 | d99c2936a62d               |
| 12 | valid-switch--d99c2936a62d |
+----+----------------------------+
2 rows in set (0.00 sec)MySQL [TESTDB]> select * from user_info;
+----+--------------+
| id | name         |
+----+--------------+
| 11 | 78f1f8ce6c8b |
+----+--------------+
1 row in set (0.01 sec)MySQL [TESTDB]> select * from user_info;
+----+--------------+
| id | name         |
+----+--------------+
| 11 | 78f1f8ce6c8b |
+----+--------------+
1 row in set (0.00 sec)MySQL [TESTDB]> select * from user_info;
+----+----------------------------+
| id | name                       |
+----+----------------------------+
| 11 | ace8d2729df2               |
| 12 | valid-switch--ace8d2729df2 |
+----+----------------------------+
2 rows in set (0.01 sec)MySQL [TESTDB]> select * from user_info;
+----+--------------+
| id | name         |
+----+--------------+
| 11 | 78f1f8ce6c8b |
+----+--------------+
1 row in set (0.00 sec)MySQL [TESTDB]> select * from user_info;
+----+----------------------------+
| id | name                       |
+----+----------------------------+
| 11 | ace8d2729df2               |
| 12 | valid-switch--ace8d2729df2 |
+----+----------------------------+
2 rows in set (0.01 sec)MySQL [TESTDB]> select * from user_info;
+----+----------------------------+
| id | name                       |
+----+----------------------------+
| 11 | d99c2936a62d               |
| 12 | valid-switch--d99c2936a62d |
+----+----------------------------+
2 rows in set (0.00 sec)MySQL [TESTDB]> select * from user_info;
+----+----------------------------+
| id | name                       |
+----+----------------------------+
| 11 | ace8d2729df2               |
| 12 | valid-switch--ace8d2729df2 |
+----+----------------------------+
2 rows in set (0.00 sec)MySQL [TESTDB]>

通过上述查询发现查询时可以落到M1、S1、S2上。双主切换成功。

由于篇幅已经挺长了，就写一篇【Mycat的简单使用（三）【分库分表】】继续介绍

版权声明：
原创博主：牛哄哄的柯南
博主原文链接：https://keafmd.blog.csdn.net/

看完如果对你有帮助，感谢点赞支持！
如果你是电脑端，看到右下角的 “一键三连” 了吗，没错点它[哈哈]

加油！

共同努力！

Keafmd

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