分片副本管理

提示

仅企业版支持

副本管理对于线上服务至关重要，CnosDB提供如下一些副本管理相关命令：

• 副本分布查看
• 增加副本
• 删除副本
• 提升节点为主
• 销毁复制组

副本以及分片相关概念可以参见 数据分片与复制

查看副本分布

show replicas

show replicas 返回复制组相关信息，包括分布在哪些节点、开始结束时间、所属的数据库名字等，如下所示：

my_db ❯ show replicas;
+------------+----------+--------------+-------------------------+-------------------------+
| replica_id | location | database     | start_time              | end_time                |
+------------+----------+--------------+-------------------------+-------------------------+
| 2          | 1001*    | usage_schema | 2023-12-19 00:00:00 UTC | 2024-12-18 00:00:00 UTC |
| 5          | 1001*    | my_db        | 2022-11-02 23:00:00 UTC | 2022-11-03 07:20:00 UTC |
+------------+----------+--------------+-------------------------+-------------------------+

* 标识复制组的主节点所位于的节点ID

增加副本

replica add

replica add 复制组在指定节点增加一个副本，如下所示：

my_db ❯ replica add replica_id 5 node_id 2001;
Query took 0.058 seconds.

my_db ❯ show replicas;
+------------+------------+--------------+-------------------------+-------------------------+
| replica_id | location   | database     | start_time              | end_time                |
+------------+------------+--------------+-------------------------+-------------------------+
| 2          | 1001*      | usage_schema | 2023-12-19 00:00:00 UTC | 2024-12-18 00:00:00 UTC |
| 5          | 1001*,2001 | my_db        | 2022-11-02 23:00:00 UTC | 2022-11-03 07:20:00 UTC |
+------------+------------+--------------+-------------------------+-------------------------+

复制组5在2001节点增加了一个副本；主节点是1001，从节点是2001

提升节点为主

replica promote

replica promote 提升一个从节点为主节点，这在更换机器等运维过程中可能会用到，如下所示：

my_db ❯ replica promote replica_id 5 node_id 2001;
Query took 0.854 seconds.

my_db ❯ show replicas;
+------------+------------+--------------+-------------------------+-------------------------+
| replica_id | location   | database     | start_time              | end_time                |
+------------+------------+--------------+-------------------------+-------------------------+
| 2          | 1001*      | usage_schema | 2023-12-19 00:00:00 UTC | 2024-12-18 00:00:00 UTC |
| 5          | 1001,2001* | my_db        | 2022-11-02 23:00:00 UTC | 2022-11-03 07:20:00 UTC |
+------------+------------+--------------+-------------------------+-------------------------+
Query took 0.010 seconds.

提升复制组5在2001节点为主节点；主节点变成2001，1001降为从节点

删除副本

replica remove

replica remove 删除一个副本，主从副本都支持删除；如果删除的是主节点则会从剩余节点随机挑选一个为新的主，如下所示：

my_db ❯ replica remove replica_id 5 node_id 2001;
Query took 0.036 seconds.

my_db ❯ show replicas;
+------------+----------+--------------+-------------------------+-------------------------+
| replica_id | location | database     | start_time              | end_time                |
+------------+----------+--------------+-------------------------+-------------------------+
| 2          | 1001*    | usage_schema | 2023-12-19 00:00:00 UTC | 2024-12-18 00:00:00 UTC |
| 5          | 1001*    | my_db        | 2022-11-02 23:00:00 UTC | 2022-11-03 07:20:00 UTC |
+------------+----------+--------------+-------------------------+-------------------------+
Query took 0.011 seconds.

删除复制组5在2001副本，剩余的副本自动变为主节点

【如果只有一个副本不允许删除，可以通过下面的销毁复制组达到删除目的】

销毁复制组

replica destory

replica destory 销毁整个复制组，如下所示：

my_db ❯ replica destory replica_id 5;
Query took 0.027 seconds.

my_db ❯ show replicas;
+------------+----------+--------------+-------------------------+-------------------------+
| replica_id | location | database     | start_time              | end_time                |
+------------+----------+--------------+-------------------------+-------------------------+
| 2          | 1001*    | usage_schema | 2023-12-19 00:00:00 UTC | 2024-12-18 00:00:00 UTC |
+------------+----------+--------------+-------------------------+-------------------------+

销毁复制组5，如果是只有一个副本的复制可以通过销毁方式达到删除目的