Common commands - Development Guide| Alibaba Cloud Documentation Center

In an E-MapReduce (EMR) cluster, you can run Kudu-related commands to perform operations. This topic describes the common commands of Kudu.

Prerequisites

An EMR cluster is created, and Kudu is selected from the optional services when you create the cluster. For more information, see Create a cluster.
You have logged on to the cluster. For more information, see Log on to a cluster.

Background information

You can run the following commands:

kudu master list: queries master nodes
kudu tserver list: queries tablet servers
kudu cluster ksck: checks the health of a cluster
kudu table list: queries all tables
kudu table describe: describes a table
kudu-tserver --dump_metrics_json and kudu-master --dump_metrics_json: check the metrics of a Kudu cluster

Limits

Kudu must be deployed in the cluster that you created.

kudu master list: queries master nodes

Syntax
```
kudu master list <your_Intranet_IP>
```
Note <your_Intranet_IP> specifies the internal IP address of a Kudu cluster. Separate multiple IP addresses with commas (,). Example: 192.168.10.59,192.168.10.60,192.168.10.61.

Example: Run the following command to query master nodes:

kudu master list 192.168.10.59,192.168.10.60,192.168.10.61

Information similar to the following output is returned:

               uuid               |          rpc-addresses           |   role
----------------------------------+----------------------------------+----------
 3ebef6e84e0d45b2b6b5d24a2911**** | emr-header-1.cluster-23****:7051 | LEADER
 a4e0160acd804e8d83b4448183f6**** | emr-header-3.cluster-23****:7051 | FOLLOWER
 0d9fdf59efce48e58f18cf212c2c**** | emr-header-2.cluster-23****:7051 | FOLLOWER

kudu tserver list: queries tablet servers

Syntax
```
kudu tserver list <your_Intranet_IP>
```

Example: Run the following command to query tablet servers:

kudu tserver list 192.168.10.59,192.168.10.60,192.168.10.61

Information similar to the following output is returned:

               uuid               |          rpc-addresses
----------------------------------+----------------------------------
 be173a301ea24997a4a7a0f78815**** | emr-worker-2.cluster-23****:7050
 2a8257107d0048728707e783035e**** | emr-worker-1.cluster-23****:7050

kudu cluster ksck: checks the health of a cluster

Syntax
```
kudu cluster ksck <your_Intranet_IP>
```

Example: Run the following command to check the health of your cluster:

kudu cluster ksck 192.168.10.59,192.168.10.60,192.168.10.61

Information similar to the following output is returned:

Master Summary
               UUID               |    Address    | Status
----------------------------------+---------------+---------
 0d9fdf59efce48e58f18cf212c2c**** | 192.168.10.60 | HEALTHY
 3ebef6e84e0d45b2b6b5d24a2911**** | 192.168.10.61 | HEALTHY
 a4e0160acd804e8d83b4448183f6**** | 192.168.10.59 | HEALTHY

               Flag                | Value  |  Tags  |         Master
-----------------------------------+--------+--------+-------------------------
 raft_get_node_instance_timeout_ms | 300000 | hidden | all 3 server(s) checked

Tablet Server Summary
               UUID               |             Address              | Status  | Location
----------------------------------+----------------------------------+---------+----------
 2a8257107d0048728707e783035e**** | emr-worker-1.cluster-234593:7050 | HEALTHY | <none>
 be173a301ea24997a4a7a0f78815**** | emr-worker-2.cluster-234593:7050 | HEALTHY | <none>

Tablet Server Location Summary
 Location |  Count
----------+---------
 <none>   |       2

               Flag                | Value  |  Tags  |      Tablet Server
-----------------------------------+--------+--------+-------------------------
 raft_get_node_instance_timeout_ms | 300000 | hidden | all 2 server(s) checked

Version Summary
 Version |         Servers
---------+-------------------------
 1.10.0  | all 5 server(s) checked

The cluster doesn't have any matching tablets

The cluster doesn't have any matching tables
Tablet Replica Count Summary
   Statistic    | Replica Count
----------------+---------------
 Minimum        | 0
 First Quartile | 0
 Median         | 0
 Third Quartile | 0
 Maximum        | 0


==================
Warnings:
==================
Some masters have unsafe, experimental, or hidden flags set
Some tablet servers have unsafe, experimental, or hidden flags set

OK

kudu table list: queries all tables

Syntax
```
kudu table list <your_Intranet_IP>
```
Example: Run the following command to query all tables:
```
kudu table list 192.168.10.59,192.168.10.60,192.168.10.61
```
Information similar to the following output is returned:
```
impala::default.my_first_table
```

kudu table describe: describes a table

Syntax
```
kudu table describe <your_Intranet_IP> <your_tablename>
```
Note <your_tablename> specifies the name of a table. You can run the kudu table list command to obtain the name of the table whose content you want to describe. For more information about the kudu table list command, see kudu table list: queries all tables. Example: impala::default.my_first_table.

Example: Run the following command to describe a table:

kudu table describe 192.168.10.59,192.168.10.60,192.168.10.61 impala::default.my_first_table

Information similar to the following output is returned:

ABLE impala::default.my_first_table (
    id INT64 NOT NULL,
    name STRING NULLABLE,
    PRIMARY KEY (id)
)
HASH (id) PARTITIONS 16
REPLICAS 1

kudu-tserver --dump_metrics_json and kudu-master --dump_metrics_json: check the metrics of a Kudu cluster

Check the metrics of tablet servers
```
kudu-tserver --dump_metrics_json
```
Check the metrics of master servers
```
kudu-master --dump_metrics_json
```