确定要切换成员的member_id。

show variables like '%server_%';
SELECT * FROM performance_schema.replication_group_members;

执行切换。

SELECT group_replication_set_as_primary('换成目标主库的member_id');

例如：

SELECT group_replication_set_as_primary('e44f902b-bf50-11ea-89d7-000000536bb6');

+--------------------------------------------------------------------------+
| group_replication_set_as_primary('e44f902b-bf50-11ea-89d7-000000536bb6') |
+--------------------------------------------------------------------------+
| Primary server switched to: e44f902b-bf50-11ea-89d7-000000536bb6         |
+--------------------------------------------------------------------------+
1 row in set (1.00 sec)

确认切换进度：

SELECT event_name, work_completed, work_estimated FROM performance_schema.events_stages_current WHERE event_name LIKE "%stage/group_rpl%";

MGR角色切换