内容纲要
概要描述
2.1.4及之后版本默认为mgr架构，不需要手动进行处理
建议安装Advisor，可以在后台检测以及进行选主的操作。
特殊情况下需进去手动切换，需进入到底层mysql。
详细说明
测试环境：kundb-2.1.8-final
- 手动切换，执行 group_replication_set_as_primary 手动切换
- 通过 kundb advisor，优雅切换（推荐方式）
方案一. 底层 mysql 执行 group_replication_set_as_primary
[root@kv2~]# kubectl get pods -owide|grep kundb1
kundb-kungate-kundb1-646f87f668-4llht 1/1 Running 0 42h 172.22.23.3 kv3
kundb-kungate-kundb1-646f87f668-ffqnt 1/1 Running 0 42h 172.22.23.2 kv2
kundb-kungate-kundb1-646f87f668-sqnjw 1/1 Running 0 42h 172.22.23.4 kv4
# 进入任一个kungate pod
[root@kv2~]# kubectl exec -it kundb-kungate-kundb1-646f87f668-sqnjw bash
# 进入底层mysql
root@kv4:/vt/manager# mysql --socket=/vdir/mnt/disk1/kundb1/kundbdata/mysql.sock -p'TEwD8*9#Qm!Pd&AG'
# 查询performance_schema.replication_group_members表
mysql> select * from performance_schema.replication_group_members;
+---------------------------+--------------------------------------+-------------+-------------+--------------+-------------+----------------+----------------------------+
| CHANNEL_NAME | MEMBER_ID | MEMBER_HOST | MEMBER_PORT | MEMBER_STATE | MEMBER_ROLE | MEMBER_VERSION | MEMBER_COMMUNICATION_STACK |
+---------------------------+--------------------------------------+-------------+-------------+--------------+-------------+----------------+----------------------------+
| group_replication_applier | 690e516f-382b-11ee-9559-be9416f75e51 | kv4 | 15006 | ONLINE | PRIMARY | 8.0.30 | XCom |
| group_replication_applier | 6916ff25-382b-11ee-ab46-8a6f5b87ea5a | kv2 | 15006 | ONLINE | SECONDARY | 8.0.30 | XCom |
| group_replication_applier | 69628fc1-382b-11ee-bcd5-8e01529700b9 | kv3 | 15006 | ONLINE | SECONDARY | 8.0.30 | XCom |
+---------------------------+--------------------------------------+-------------+-------------+--------------+-------------+----------------+----------------------------+
3 rows in set (0.00 sec)
# 前面的信息可以看到，主节点是kv4，这里我们将主切换成kv2
# 其中6916ff25-382b-11ee-ab46-8a6f5b87ea5a 为需要切换节点的MEMBER_ID
mysql> select group_replication_set_as_primary('6916ff25-382b-11ee-ab46-8a6f5b87ea5a');
+--------------------------------------------------------------------------+
| group_replication_set_as_primary('6916ff25-382b-11ee-ab46-8a6f5b87ea5a') |
+--------------------------------------------------------------------------+
| Primary server switched to: 6916ff25-382b-11ee-ab46-8a6f5b87ea5a |
+--------------------------------------------------------------------------+
1 row in set (0.28 sec)
# 再次查看，kv2变成了 PRIMARY
mysql> select * from performance_schema.replication_group_members;
+---------------------------+--------------------------------------+-------------+-------------+--------------+-------------+----------------+----------------------------+
| CHANNEL_NAME | MEMBER_ID | MEMBER_HOST | MEMBER_PORT | MEMBER_STATE | MEMBER_ROLE | MEMBER_VERSION | MEMBER_COMMUNICATION_STACK |
+---------------------------+--------------------------------------+-------------+-------------+--------------+-------------+----------------+----------------------------+
| group_replication_applier | 690e516f-382b-11ee-9559-be9416f75e51 | kv4 | 15006 | ONLINE | SECONDARY | 8.0.30 | XCom |
| group_replication_applier | 6916ff25-382b-11ee-ab46-8a6f5b87ea5a | kv2 | 15006 | ONLINE | PRIMARY | 8.0.30 | XCom |
| group_replication_applier | 69628fc1-382b-11ee-bcd5-8e01529700b9 | kv3 | 15006 | ONLINE | SECONDARY | 8.0.30 | XCom |
+---------------------------+--------------------------------------+-------------+-------------+--------------+-------------+----------------+----------------------------+
3 rows in set (0.00 sec)
方案二. Advisor切换
进入KUNDBA服务，找到对应的kundb服务进入，点击下面的主备切换按钮
选择优雅切换，从kv2切换至kv3，点击确定
切换前需要确保集群的健康状态，以及流水落后现象不严重。如果不满足条件，需要做相应的修复后再进行操作
等待一会之后，页面会提示 shard 优雅切换成功(1/1)
点击存储节点，可以看到切换记录
