MySQL运维实战之ProxySQL（9.5）proxysql和MySQL Group Replication配合使用

作者：俊达

如果后端MySQL使用了Group Replication，可通过配置mysql_group_replication_hostgroups表来实现高可用

1 mysql_group_replication_hostgroups

字段	描述
writer_hostgroup	写hostgroup。read_only和super_read_only OFF的节点。
backup_writer_hostgroup	如果可写的节点数超过max_writers，将超出限制的节点的hostgroup设置为backup_writer_hostgroup
reader_hostgroup	读hostgroup。read_only或super_read_only ON的节点放入改hostgroup。
offline_hostgroup	如果后端mysql实例健康检查失败或group replication状态异常，则会被移入offline_hostgroup
active	是否启用。
max_writers	可写节点数上限。超过该限制数量的可写节点会放入backup_writer_hostgroup
writer_is_also_reader	如果设置为0，则只有只读节点加入reader_hostgroup。
	如果设置成1，则writer_hostgroup中的节点会同时加入reader_hostgroup；如果设置为2，则只会把backup_writer_hostgroup中的节点加入reader_hostgroup。（如果backup_writer_hostgroup中无节点，好像也会把writer_hostgroup中的节点加入到reader_hostgroup，疑似bug）。
max_transactions_behind
comment

2 配置集群节点

insert into mysql_servers (hostgroup_id, hostname, port, max_replication_lag)
values ( 200, '172.16.121.236', 3306, 3);insert into mysql_servers (hostgroup_id, hostname, port, max_replication_lag)
values ( 210, '172.16.121.237', 3306, 3);load mysql servers  to runtime; 
SAVE MYSQL servers  TO DISK;

3 配置集群信息

insert into mysql_group_replication_hostgroups
(writer_hostgroup, backup_writer_hostgroup, reader_hostgroup, 
offline_hostgroup, active, max_writers, writer_is_also_reader,
max_transactions_behind, comment)
values(200, 201, 210, 202, 1, 1, 0, 0, 'mysql mgr cluster 1');load mysql servers to runtime;
save mysql servers to disk;

4 创建和配置用户信息

在后端创建用户

mysql> create user 'mgr'@'%' identified by 'mgr123';
Query OK, 0 rows affected (0.06 sec)mysql> grant select,insert,update,delete,create,drop on *.* to 'mgr'@'%';
Query OK, 0 rows affected (0.02 sec)

在proxysql配置用户信息

insert into mysql_users
(username, password, transaction_persistent, backend, frontend, default_hostgroup, comment)
values ('mgr', 'mgr123', 1, 1, 1, 200, 'backend user for mgr cluster');load mysql users  to runtime; 
save mysql users to disk;