Using a Kudu Client

Kudu is a columnar storage manager developed for the Apache Hadoop platform. Kudu shares the common technical properties of Hadoop ecosystem applications. It is horizontally scalable and supports highly available operations.

Prerequisites

The cluster client has been installed. For example, the client is installed in the /opt/hadoopclient directory. The client directory in the following operations is only an example. Change it to the actual installation directory.

Procedure

Log in to the node where the client is installed as the client installation user.

Run the su - omm command to switch to user omm.
Run the following command to go to the client installation directory:

cd /opt/hadoopclient
Run the following command to configure environment variables:

source bigdata_env
Run the Kudu command line tool.

Run the command line tool of the Kudu component to view help information.

kudu -h

The command output is as follows:
```
Usage: kudu <command> [<args>]
 
<command> can be one of the following:
         cluster   Operate on a Kudu cluster
        diagnose   Diagnostic tools for Kudu servers and clusters
              fs   Operate on a local Kudu filesystem
             hms   Operate on remote Hive Metastores
   local_replica   Operate on local tablet replicas via the local filesystem
          master   Operate on a Kudu Master
             pbc   Operate on PBC (protobuf container) files
            perf   Measure the performance of a Kudu cluster
  remote_replica   Operate on remote tablet replicas on a Kudu Tablet Server
           table   Operate on Kudu tables
          tablet   Operate on remote Kudu tablets
            test   Various test actions
         tserver   Operate on a Kudu Tablet Server
             wal   Operate on WAL (write-ahead log) files
```
The Kudu command line tool does not support DDL and DML operations, but provides the refined query function for the cluster, master, tserver, fs, and table parameters.

Common operations:
- Check the tables in the current cluster.
  kudu table list KuduMaster instance IP1:7051, KuduMaster instance IP2:7051, KuduMaster instance IP3:7051
- Query the configurations of the KuduMaster instance of the Kudu service.
  kudu master get_flags KuduMaster instance IP:7051
- Query the schema of a table.
  kudu table describe KuduMaster instance IP1:7051, KuduMaster instance IP2:7051, KuduMaster instance IP3:7051 Table name
- Delete a table.
  kudu table delete KuduMaster instance IP1:7051, KuduMaster instance IP2:7051, KuduMaster instance IP3:7051 Table name
  
  To obtain the IP address of the KuduMaster instance, choose Components > Kudu > Instances on the cluster details page.