CLUSTER_INFO
CLUSTER_INFO 表提供了集群的节点拓扑信息。
sql
USE INFORMATION_SCHEMA;
DESC TABLE CLUSTER_INFO;USE INFORMATION_SCHEMA;
DESC TABLE CLUSTER_INFO;输出如下：
sql
+-------------+----------------------+------+------+---------+---------------+
| Column | Type | Key | Null | Default | Semantic Type |
+-------------+----------------------+------+------+---------+---------------+
| peer_id | Int64 | | NO | | FIELD |
| peer_type | String | | NO | | FIELD |
| peer_addr | String | | YES | | FIELD |
| version | String | | NO | | FIELD |
| git_commit | String | | NO | | FIELD |
| start_time | TimestampMillisecond | | YES | | FIELD |
| uptime | String | | YES | | FIELD |
| active_time | String | | YES | | FIELD |
+-------------+----------------------+------+------+---------+---------------++-------------+----------------------+------+------+---------+---------------+
| Column | Type | Key | Null | Default | Semantic Type |
+-------------+----------------------+------+------+---------+---------------+
| peer_id | Int64 | | NO | | FIELD |
| peer_type | String | | NO | | FIELD |
| peer_addr | String | | YES | | FIELD |
| version | String | | NO | | FIELD |
| git_commit | String | | NO | | FIELD |
| start_time | TimestampMillisecond | | YES | | FIELD |
| uptime | String | | YES | | FIELD |
| active_time | String | | YES | | FIELD |
+-------------+----------------------+------+------+---------+---------------+每个列的含义：
peer_id: 节点的服务器 ID。对于 standalone 来讲，该字段总是为0，对于集群模式下的 frontend 该字段总为-1。因为在这两种情况下，该字段没有实际含义。peer_type: 节点类型, 分布式集群里可能是METASRV、FRONTEND或者DATANODE。单机模式显示为STANDALONE。peer_addr: 节点的 gRPC 服务地址。对于单机部署，该字段总为空。version: 节点的版本号，形如0.7.2的字符串。start_time: 节点的启动时间。uptime: 节点的持续运行时间，形如24h 10m 59s 150ms的字符串。active_time: 距离节点上一次活跃（也就是发送心跳请求）过去的时间，形如24h 10m 59s 150ms的字符串。单机模式下该字段总为空。
尝试查询下这张表：
sql
SELECT * FROM CLUSTER_INFO;SELECT * FROM CLUSTER_INFO;一个单机模式的样例输出：
sql
+---------+------------+-----------+---------+------------+-------------------------+--------+-------------+
| peer_id | peer_type | peer_addr | version | git_commit | start_time | uptime | active_time |
+---------+------------+-----------+---------+------------+-------------------------+--------+-------------+
| 0 | STANDALONE | | 0.7.2 | 86ab3d9 | 2024-04-30T06:40:02.074 | 18ms | |
+---------+------------+-----------+---------+------------+-------------------------+--------+-------------++---------+------------+-----------+---------+------------+-------------------------+--------+-------------+
| peer_id | peer_type | peer_addr | version | git_commit | start_time | uptime | active_time |
+---------+------------+-----------+---------+------------+-------------------------+--------+-------------+
| 0 | STANDALONE | | 0.7.2 | 86ab3d9 | 2024-04-30T06:40:02.074 | 18ms | |
+---------+------------+-----------+---------+------------+-------------------------+--------+-------------+另一个输出来自一个分布式集群，它有三个 Datanode、一个 Frontend 和一个 Metasrv：
sql
+---------+-----------+----------------+---------+------------+-------------------------+----------+-------------+
| peer_id | peer_type | peer_addr | version | git_commit | start_time | uptime | active_time |
+---------+-----------+----------------+---------+------------+-------------------------+----------+-------------+
| 1 | DATANODE | 127.0.0.1:4101 | 0.7.2 | 86ab3d9 | 2024-04-30T06:40:04.791 | 4s 478ms | 1s 467ms |
| 2 | DATANODE | 127.0.0.1:4102 | 0.7.2 | 86ab3d9 | 2024-04-30T06:40:06.098 | 3s 171ms | 162ms |
| 3 | DATANODE | 127.0.0.1:4103 | 0.7.2 | 86ab3d9 | 2024-04-30T06:40:07.425 | 1s 844ms | 1s 839ms |
| -1 | FRONTEND | 127.0.0.1:4001 | 0.7.2 | 86ab3d9 | 2024-04-30T06:40:08.815 | 454ms | 47ms |
| 0 | METASRV | 127.0.0.1:3002 | unknown | unknown | | | |
+---------+-----------+----------------+---------+------------+-------------------------+----------+-------------++---------+-----------+----------------+---------+------------+-------------------------+----------+-------------+
| peer_id | peer_type | peer_addr | version | git_commit | start_time | uptime | active_time |
+---------+-----------+----------------+---------+------------+-------------------------+----------+-------------+
| 1 | DATANODE | 127.0.0.1:4101 | 0.7.2 | 86ab3d9 | 2024-04-30T06:40:04.791 | 4s 478ms | 1s 467ms |
| 2 | DATANODE | 127.0.0.1:4102 | 0.7.2 | 86ab3d9 | 2024-04-30T06:40:06.098 | 3s 171ms | 162ms |
| 3 | DATANODE | 127.0.0.1:4103 | 0.7.2 | 86ab3d9 | 2024-04-30T06:40:07.425 | 1s 844ms | 1s 839ms |
| -1 | FRONTEND | 127.0.0.1:4001 | 0.7.2 | 86ab3d9 | 2024-04-30T06:40:08.815 | 454ms | 47ms |
| 0 | METASRV | 127.0.0.1:3002 | unknown | unknown | | | |
+---------+-----------+----------------+---------+------------+-------------------------+----------+-------------+