MGR 5.7 多主集群搭建

参考文档：

https://dev.mysql.com/doc/refman/5.7/en/group-replication-configuring-instances.html

https://www.cnblogs.com/manger/p/7211932.html

1、搭建三个MYSQL 5.7，暂时不需要配置为主从复制，

192.168.150.101

192.168.150.102

192.168.150.103

安装方法如下：

https://www.cnblogs.com/nanxiang/p/12888222.html

三个实例，server_id分别配置为1，2，3

2、三个实例安装组复制插件

mysql> INSTALL PLUGIN group_replication SONAME 'group_replication.so';
Query OK, 0 rows affected (0.03 sec)

3、参考组复制要求，修改配置文件，重启数据库

https://dev.mysql.com/doc/refman/5.7/en/group-replication-requirements.html

my.cnf，各个节点，要做对应的修改，然后重启数据库生效

#MGR基础配置
disabled_storage_engines="MyISAM,BLACKHOLE,FEDERATED,ARCHIVE,MEMORY"
server_id=1 #每个节点要不一样
log-bin=mysql-bin
log-slave-updates
binlog-format=row
binlog-checksum=NONE
gtid_mode=ON
enforce_gtid_consistency=ON
master_info_repository=TABLE 
relay_log_info_repository=TABLE
transaction-write-set-extraction=XXHASH64 
##lower-case-table-names=1   这个参数在初始化时默认就是1，可以不用修改。
slave_parallel_type=LOGICAL_CLOCK
slave_parallel_workers=4
slave_preserve_commit_order=1

#MGR参数配置
transaction_write_set_extraction = XXHASH64  #以便在server收集写集合的同时将其记录到二进制日志。写集合基于每行的主键，并且是行更改后的唯一标识此标识将用于检测冲突。
loose-group_replication_group_name = 'ce9be252-2b71-11e6-b8f4-00212889f856' #组的名字可以随便起,但不能用主机的GTID，select uuid()可随机获取一个UUID
loose-group_replication_start_on_boot = off  #为了避免每次启动自动引导具有相同名称的第二个组,所以设置为OFF。
loose-group_replication_bootstrap_group = off #同上
loose-group_replication_local_address = '192.168.150.101:33061' #写自己主机所在IP
loose-group_replication_group_seeds ='192.168.150.101:33061,192.168.150.102:33061,192.168.150.103:33061'
loose-group_replication_single_primary_mode = off  #关闭单主模式的参数
loose-group_replication_enforce_update_everywhere_checks = on #开启多主模式的参数

4、在 101 节点创建repl用户，并授权

mysql>SET GLOBAL group_replication_bootstrap_group=ON; 

#这句只有server88,在第一次执行引导组的时候执行.

mysql> create user repl identified by '123456';
Query OK, 0 rows affected (10.01 sec)

mysql> grant all privileges on *.* to repl;
Query OK, 0 rows affected (0.00 sec)

  mysql> START GROUP_REPLICATION;

mysql> SET GLOBAL group_replication_bootstrap_group=OFF;

查询组内只有自己

mysql> SELECT * FROM performance_schema.replication_group_members;
+---------------------------+--------------------------------------+-------------+-------------+--------------+
| CHANNEL_NAME              | MEMBER_ID                            | MEMBER_HOST | MEMBER_PORT | MEMBER_STATE |
+---------------------------+--------------------------------------+-------------+-------------+--------------+
| group_replication_applier | 9fef2262-97b1-11ea-92b5-000c29cd3ff3 | host101     |        3306 | ONLINE       |
+---------------------------+--------------------------------------+-------------+-------------+--------------+

5、102和103节点分别加入到组复制中

SET SQL_LOG_BIN=0;
create user repl identified by '123456';
grant all privileges on *.* to repl;
SET SQL_LOG_BIN=1;
CHANGE MASTER TO MASTER_USER='repl',MASTER_PASSWORD='123456' FOR CHANNEL 'group_replication_recovery';
START GROUP_REPLICATION;

6、查询101节点的replication_group_members表

mysql> SELECT * FROM performance_schema.replication_group_members;
+---------------------------+--------------------------------------+-------------+-------------+--------------+
| CHANNEL_NAME              | MEMBER_ID                            | MEMBER_HOST | MEMBER_PORT | MEMBER_STATE |
+---------------------------+--------------------------------------+-------------+-------------+--------------+
| group_replication_applier | 83f050f5-a871-11ea-9161-000c29fa663f | host103     |        3306 | ONLINE       |
| group_replication_applier | 9fef2262-97b1-11ea-92b5-000c29cd3ff3 | host101     |        3306 | ONLINE       |
| group_replication_applier | adc4403d-97b2-11ea-b803-000c298076e0 | host102     |        3306 | ONLINE       |
+---------------------------+--------------------------------------+-------------+-------------+--------------+

7、测试多主MGR

101节点

mysql> create database ceshi;
Query OK, 1 row affected (10.01 sec)

102节点

mysql> create table t1(id int primary key);
Query OK, 0 rows affected (0.02 sec)

103节点

mysql> insert into t1 select 1;
Query OK, 1 row affected (0.01 sec)
Records: 1  Duplicates: 0  Warnings: 0

101节点

mysql> select * from ceshi.t1;
+----+
| id |
+----+
|  1 |
+----+
1 row in set (0.00 sec)

踩坑：

【2020-11-15T14:29:40.846054Z 31 [ERROR] Slave I/O for channel 'group_replication_recovery': error connecting to master 'repl@host101:3306' - retry-time: 60 retries: 1, Error_code: 2005】

连接超时，我没有配置/etc/hosts文件，配置如下后，解决问题。

192.168.150.101 host101
192.168.150.102 host102
192.168.150.103 host103

【2020-11-15T14:40:53.714400Z 0 [ERROR] Plugin group_replication reported: 'This member has more executed transactions than those present in the group. Local transactions: adc4403d-97b2-11ea-b803-000c298076e0:1,

ce9be252-2b71-11e6-b8f4-00212889f856:1 > Group transactions: ce9be252-2b71-11e6-b8f4-00212889f856:1-6'
2020-11-15T14:40:53.714449Z 0 [ERROR] Plugin group_replication reported: 'The member contains transactions not present in the group. The member will now exit the group.'】

我用的已有环境，一直在做测试，本地事务比组内事还要多，所以报错了。

解决方法：

reset master; ---初始化一下位点，重新启动组复制即可。