CLUSTER_INFO
CLUSTER_INFO 表提供了集群的节点拓扑信息。
USE INFORMATION_SCHEMA;
DESC TABLE CLUSTER_INFO;
输出如下：
+-----------------------+----------------------+------+------+---------+---------------+
| Column | Type | Key | Null | Default | Semantic Type |
+-----------------------+----------------------+------+------+---------+---------------+
| peer_id | Int64 | | NO | | FIELD |
| peer_type | String | | NO | | FIELD |
| peer_addr | String | | YES | | FIELD |
| peer_hostname | String | | YES | | FIELD |
| total_cpu_millicores | Int64 | | NO | | FIELD |
| total_memory_bytes | Int64 | | NO | | FIELD |
| cpu_usage_millicores | Int64 | | NO | | FIELD |
| memory_usage_bytes | Int64 | | NO | | FIELD |
| version | String | | NO | | FIELD |
| git_commit | String | | NO | | FIELD |
| start_time | TimestampMillisecond | | YES | | FIELD |
| uptime | String | | YES | | FIELD |
| active_time | String | | YES | | FIELD |
| node_status | 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。peer_hostname: 节点的主机名。total_cpu_millicores: 节点的总 CPU 毫核数。total_memory_bytes: 节点的总内存字节数。cpu_usage_millicores: 节点的 CPU 使用毫核数。此功能仅在容器化环境 (cgroup v2) 中有效。memory_usage_bytes: 节点的内存使用字节数。此功能仅在容器化环境 (cgroup v2) 中有效。version: 节点的版本号，形如0.7.2的字符串。git_commit: 节点编译的 git 版本号。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。node_status: 节点的状态信息。
尝试查询下这张表：
SELECT * FROM CLUSTER_INFO;
一个单机模式的样例输出：
+---------+------------+-----------+---------------+----------------------+--------------------+----------------------+--------------------+---------+-----------+----------------------------+--------+-------------+-------------+
| peer_id | peer_type | peer_addr | peer_hostname | total_cpu_millicores | total_memory_bytes | cpu_usage_millicores | memory_usage_bytes | version | git_commit| start_time | uptime | active_time | node_status |
+---------+------------+-----------+---------------+----------------------+--------------------+----------------------+--------------------+---------+-----------+----------------------------+--------+-------------+-------------+
| 0 | STANDALONE | | | 16000 | 17179869184 | 0 | 0 | 0.7.2 | 86ab3d9 | 2024-04-30T06:40:02.074 | 18ms | | NULL |
+---------+------------+-----------+---------------+----------------------+--------------------+----------------------+--------------------+---------+-----------+----------------------------+--------+-------------+-------------+
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：
+---------+-----------+----------------+-------------------------------------+----------------------+--------------------+----------------------+--------------------+---------+-----------+----------------------------+----------+-------------+-------------------------------------------------------------------+
| peer_id | peer_type | peer_addr | peer_hostname | total_cpu_millicores | total_memory_bytes | cpu_usage_millicores | memory_usage_bytes | version | git_commit| start_time | uptime | active_time | node_status |
+---------+-----------+----------------+-------------------------------------+----------------------+--------------------+----------------------+--------------------+---------+-----------+----------------------------+----------+-------------+-------------------------------------------------------------------+
| 1 | DATANODE | 127.0.0.1:4101 | mycluster-datanode-0 | 1000 | 1073741824 | 1 | 34570240 | 0.7.2 | 86ab3d9 | 2024-04-30T06:40:04.791 | 4s 478ms | 1s 467ms | {"workloads":["hybrid"],"leader_regions":46,"follower_regions":0} |
| 2 | DATANODE | 127.0.0.1:4102 | mycluster-datanode-1 | 1000 | 1073741824 | 1 | 38170624 | 0.7.2 | 86ab3d9 | 2024-04-30T06:40:06.098 | 3s 171ms | 162ms | {"workloads":["hybrid"],"leader_regions":46,"follower_regions":0} |
| 3 | DATANODE | 127.0.0.1:4103 | mycluster-datanode-2 | 1000 | 1073741824 | 1 | 37085184 | 0.7.2 | 86ab3d9 | 2024-04-30T06:40:07.425 | 1s 844ms | 1s 839ms | {"workloads":["hybrid"],"leader_regions":46,"follower_regions":0} |
| -1 | FRONTEND | 127.0.0.1:4001 | mycluster-frontend-6c5d4bcf78-m7jtx | 1000 | 1073741824 | 1 | 45465600 | 0.7.2 | 86ab3d9 | 2024-04-30T06:40:08.815 | 454ms | 47ms | NULL |
| 0 | METASRV | 127.0.0.1:3002 | mycluster-meta-54bd44bd94-g8dzm | 1000 | 1073741824 | 0 | 28368896 | unknown | unknown | | | | {"is_leader":true} |
+---------+-----------+----------------+-------------------------------------+----------------------+--------------------+----------------------+--------------------+---------+-----------+----------------------------+----------+-------------+-------------------------------------------------------------------+