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E-MapReduce:Common commands

Last Updated:Sep 05, 2023

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.

Query master nodes

  • Syntax

    kudu master list <Internal IP addresses of master nodes>
    Note

    If your cluster contains multiple master nodes, separate the internal IP addresses of the master nodes with commas (,). Example: 192.168.**.**,192.168.**.**,192.168.**.**.

  • Example: Run the following command to query master nodes:

    kudu master list 192.168.**.**,192.168.**.**,192.168.**.**

    Information similar to the following output is returned:

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

Query tablet servers

  • Syntax

    kudu tserver list <Internal IP addresses of master nodes>
  • Example: Run the following command to query tablet servers:

    kudu tserver list 192.168.**.**,192.168.**.**,192.168.**.**

    Information similar to the following output is returned:

                   uuid               |                         rpc-addresses
    ----------------------------------+---------------------------------------------------------------
     f54035d36a974241b125888f6dd3**** | core-1-1.c-4ac28de1af8c****.cn-hangzhou.emr.aliyuncs.com:7050
     5f448cb2ac1f47a0ab97aab066ad**** | core-1-2.c-4ac28de1af8c****.cn-hangzhou.emr.aliyuncs.com:7050

Check the health of a cluster

  • Syntax

    kudu cluster ksck <Internal IP addresses of master nodes>
  • Example: Run the following command to check the health of your cluster:

    kudu cluster ksck 192.168.**.**,192.168.**.**,192.168.**.**

    Information similar to the following output is returned:

    Master Summary
                   UUID               |    Address    | Status
    ----------------------------------+---------------+---------
     0d9fdf59efce48e58f18cf212c2c**** | 192.168.**.** | HEALTHY
     3ebef6e84e0d45b2b6b5d24a2911**** | 192.168.**.** | HEALTHY
     a4e0160acd804e8d83b4448183f6**** | 192.168.**.** | 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**** | core-1-1.cluster-234593:7050 | HEALTHY | <none>
     be173a301ea24997a4a7a0f78815**** | core-1-2.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

Query all tables

  • Syntax

    kudu table list <Internal IP addresses of master nodes>
  • Example: Run the following command to query all tables:

    kudu table list 192.168.**.**,192.168.**.**,192.168.**.**

    Information similar to the following output is returned:

    impala::default.my_first_table

Describe a table

  • Syntax

    kudu table describe <Internal IP addresses of master nodes> <your_tablename>
    Note

    <your_tablename> in the code 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. Example: impala::default.my_first_table.

  • Example: Run the following command to describe a table:

    kudu table describe 192.168.**.**,192.168.**.**,192.168.**.** 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

Check the metrics of a cluster

  • Check the metrics of master nodes

    kudu-master --dump_metrics_json
  • Check the metrics of tablet servers

    kudu-tserver --dump_metrics_json