MySQL MGR

一、安装插件（先进入数据库安装插件）

INSTALL PLUGIN group_replication SONAME 'group_replication.so';

 二、调整MySQL各节点的配置文件并重启MySQL服务(所有节点执行) 带*的需要重点检查

## config master
server-id               				= 17218228149
log-bin                 				= mysql-bin
master_info_repository  				= TABLE
binlog_format           				= ROW
expire_logs_days        				= 7
sync_binlog             				= 1
gtid_mode                				= on
enforce-gtid-consistency 				= true
binlog_rows_query_log_events 			        = on
*binlog_checksum　　　　　　　　　　　　　　　　　　　　　　　　 =‘none’


## config slave
skip-slave-start
slave-parallel-workers  				= 8
slave-parallel-type 					= LOGICAL_CLOCK
*slave_preserve_commit_order 			        = 1
log_slave_updates      					= 1
*report_host						= 192.168.1.149（本机IP）


## config relay log
relay-log               				= relay-log
relay_log_recovery      				= ON
sync_relay_log          				= 0
relay_log_info_repository 				= TABLE


## config group replication
transaction_write_set_extraction		　　　= XXHASH64
*loose-group_replication_group_name	 	　　　= "412cbc47-74e7-11eb-8283-000c2915e93c"   #可以随便填但是要遵守UUID的格式（三台一致）
loose-group_replication_start_on_boot	　　　　　　　　= OFF
loose-group_replication_bootstrap_group	　　　　　　　　= OFF
*loose-group_replication_local_address	　　　　　　　　= "192.168.1.149:33581"
*loose-group_replication_group_seeds		　　　= "192.168.1.147:33581,192.168.1.148:33581,192.168.1.149:33581"
*loose-group_replication_ip_whitelist	　　　　　　　 = "192.168.1.147,192.168.1.148,192.168.1.149"

 三、配置MGR通信账号，并清理MASTER(所有节点执行)

CREATE USER repl@'%' IDENTIFIED BY 'repl';
GRANT REPLICATION SLAVE ON *.* TO repl@'%';
RESET MASTER;
RESET SLAVE ALL;

 四、创建MGR依赖的复制环境(所有节点执行)

CHANGE MASTER TO MASTER_USER='repl', 
MASTER_PASSWORD='repl'
FOR CHANNEL 'group_replication_recovery';

 五、在主节点上启动MGR(在节点192.168.1.147上执行)

SET GLOBAL group_replication_bootstrap_group=ON;
START group_replication;
SET GLOBAL group_replication_bootstrap_group=off;

 六、在辅助节点上启动MGR(在节点192.168.1.148和在节点192.168.1.149上执行)

START group_replication;

 七、搭建完成后，可以使用下面语句查看状态：

## 查看各节点状态
SELECT * 
FROM performance_schema.replication_group_members;

## 查看当前MGR模式(单主还是多主)
SELECT @@group_replication_single_primary_mode;

 八、判断节点状态

## 查看当前节点状态
SELECT member_state 
FROM performance_schema.replication_group_members 
WHERE member_id=@@server_uuid;


## 通过节点是否可写来判断群集是否为主节点
SELECT * 
FROM performance_schema.global_variables 
WHERE variable_name IN ('read_only', 'super_read_only');

九、MGR成员的五种状态：

ONLINE: The member is in a fully functioning state.
该成员处于完全运作状态。

RECOVERING: The server has joined a group from which it is retrieving data.
服务器已加入从中检索数据的组。

OFFLINE: The group replication plugin is installed but has not been started.


组复制插件已安装，但尚未启动。 

ERROR: The member has encountered an error, either during applying transactions or during the recovery phase, and is not participating in the group's transactions.


成员在应用事务或恢复阶段遇到错误，并且未参与组的事务。 

UNREACHABLE: The failure detection process suspects that this member cannot be contacted, because the group messages have timed out.


失败检测进程怀疑无法联系此成员，因为组消息已超时。 

 

 十、新增MGR节点

目前MySQL不支持自动扩展新节点并将全量数据同步到新节点，因此需要：

1、备份任一节点数据(MySQLDump或Xtrabackup)至新节点并还原

2、在新节点上设置与备份数据对应的Executed_Gtid_Set

3、在新节点上执行下面命令直接启动MGR复制即可。

CHANGE MASTER TO MASTER_USER='repl', 
MASTER_PASSWORD='repl'
FOR CHANNEL 'group_replication_recovery';

START GROUP_REPLICATION;