In the earlier chapters, we've got seen the set up of Impala using Cloudera and its architecture.
This chapter explains a way to begin Impala Shell and the various options of the shell.
The commands of Impala shell are classified as general commands, query specific options, and table and database specific options, as explained below.
Table and Database specific options
Open the cloudera terminal, sign in as superuser, and type cloudera as password as shown below.
Start Impala shell by typing the following command −
The general purpose commands of Impala are explained below −
The help command of Impala shell gives you a list of the commands available in Impala −
The version command gives you the current version of Impala, as shown below.
The history command of Impala displays the last 10 commands executed in the shell. Following is the example of the history command. Here we have executed 5 commands, namely, version, help, show, use, and history.
You can come out of the Impala shell using the quit or exit command, as shown below.
The connect command is used to connect to a given instance of Impala. In case you do not specify any instance, then it connects to the default port 21000 as shown below.
The query specific commands of Impala accept a query. They are explained below −
The explain command returns the execution plan for the given query.
The profile command displays the low-level information about the recent query. This command is used for diagnosis and performance tuning of a query. Following is the example of a profile command. In this scenario, the profile command returns the low-level information of explain query.
The following table lists out the table and data specific options in Impala.
|Sr.No||Command & Explanation|
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