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| <h1 class="title topictitle1" id="ariaid-title1">Connecting to Impala Daemon from impala-shell</h1> |
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| <div class="body conbody"> |
| |
| <div class="p"> Within an <span class="keyword cmdname">impala-shell</span> session, you can only issue |
| queries while connected to an instance of the <span class="keyword cmdname">impalad</span> |
| daemon. You can specify the connection information: <ul class="ul"> |
| <li class="li"> Through command-line options when you run the |
| <span class="keyword cmdname">impala-shell</span> command. </li> |
| |
| <li class="li"> Through a configuration file that is read when you run the |
| <span class="keyword cmdname">impala-shell</span> command. </li> |
| |
| <li class="li"> During an <span class="keyword cmdname">impala-shell</span> session, by issuing a |
| <code class="ph codeph">CONNECT</code> command. </li> |
| |
| </ul> |
| <div class="note note"><span class="notetitle">Note:</span> You cannot connect to the 3.2 or earlier versions of Impala |
| using the <code class="ph codeph">'hs2'</code> or <code class="ph codeph">'hs2-http'</code> protocol |
| (<code class="ph codeph">--protocol</code> option).</div> |
| See <a class="xref" href="impala_shell_options.html">impala-shell Configuration Options</a> for the command-line and configuration |
| file options you can use. </div> |
| |
| |
| <p class="p"> You can connect to any Impala daemon (<span class="keyword cmdname">impalad</span>), and |
| that daemon coordinates the execution of all queries sent to it. </p> |
| |
| |
| <p class="p"> |
| For simplicity during development, you might always connect to the same host, perhaps running <span class="keyword cmdname">impala-shell</span> on |
| the same host as <span class="keyword cmdname">impalad</span> and specifying the hostname as <code class="ph codeph">localhost</code>. |
| </p> |
| |
| |
| <p class="p"> In a production environment, you might enable load balancing, in which |
| you connect to specific host/port combination but queries are forwarded to |
| arbitrary hosts. This technique spreads the overhead of acting as the |
| coordinator node among all the Impala daemons in the cluster. See <a class="xref" href="impala_proxy.html">Using Impala through a Proxy for High Availability</a> for details. </p> |
| |
| |
| <p class="p"> |
| <strong class="ph b">To connect to an Impala during shell startup:</strong> |
| </p> |
| |
| |
| <ol class="ol"> |
| <li class="li"> Locate the hostname that is running an instance of the |
| <span class="keyword cmdname">impalad</span> daemon. If that <span class="keyword cmdname">impalad</span> |
| uses a non-default port (something other than port 21000) for |
| <span class="keyword cmdname">impala-shell</span> connections, find out the port number |
| also. </li> |
| |
| |
| <li class="li"> Use the <code class="ph codeph">-i</code> option to the |
| <span class="keyword cmdname">impala-shell</span> interpreter to specify the connection |
| information for that instance of <span class="keyword cmdname">impalad</span>: |
| <pre class="pre codeblock"><code># When you are connecting to an impalad running on the same machine. |
| # The prompt will reflect the current hostname. |
| $ impala-shell |
| |
| # When you are connecting to an impalad running on a remote machine, and impalad is listening |
| # on a non-default port over the HTTP HiveServer2 protocol. |
| $ impala-shell -i <var class="keyword varname">some.other.hostname</var>:<var class="keyword varname">port_number</var> --protocol='hs2-http' |
| # When you are connecting to an impalad running on a remote machine, and impalad is listening |
| # on a non-default port. |
| $ impala-shell -i <var class="keyword varname">some.other.hostname</var>:<var class="keyword varname">port_number</var> |
| </code></pre> |
| </li> |
| |
| </ol> |
| |
| |
| <p class="p"> |
| <strong class="ph b">To connect to an Impala in the<span class="keyword cmdname">impala-shell</span> |
| session:</strong> |
| </p> |
| |
| |
| <ol class="ol"> |
| <li class="li"> Start the Impala shell with no connection: |
| <pre class="pre codeblock"><code>$ impala-shell</code></pre></li> |
| |
| |
| <li class="li"> Locate the hostname that is running the <span class="keyword cmdname">impalad</span> |
| daemon. If that <span class="keyword cmdname">impalad</span> uses a non-default port |
| (something other than port 21000) for <span class="keyword cmdname">impala-shell</span> |
| connections, find out the port number also. </li> |
| |
| |
| <li class="li"> Use the <code class="ph codeph">connect</code> command to connect to an Impala |
| instance. Enter a command of the form: |
| <pre class="pre codeblock"><code>[Not connected] > connect <var class="keyword varname">impalad-host</var></code></pre><div class="note note"><span class="notetitle">Note:</span> |
| Replace <var class="keyword varname">impalad-host</var> with the hostname you have |
| configured to run Impala in your environment. The changed prompt |
| indicates a successful connection. </div> |
| |
| </li> |
| |
| </ol> |
| |
| |
| <p class="p"> |
| <strong class="ph b">To start <span class="keyword cmdname">impala-shell</span> in a specific database:</strong> |
| </p> |
| |
| |
| <p class="p"> You can use all the same connection options as in previous examples. For |
| simplicity, these examples assume that you are logged into one of the |
| Impala daemons. </p> |
| |
| |
| <ol class="ol"> |
| <li class="li"> |
| Find the name of the database containing the relevant tables, views, and so |
| on that you want to operate on. |
| </li> |
| |
| |
| <li class="li"> |
| Use the <code class="ph codeph">-d</code> option to the |
| <span class="keyword cmdname">impala-shell</span> interpreter to connect and immediately |
| switch to the specified database, without the need for a <code class="ph codeph">USE</code> |
| statement or fully qualified names: |
| <pre class="pre codeblock"><code># Subsequent queries with unqualified names operate on |
| # tables, views, and so on inside the database named 'staging'. |
| $ impala-shell -i localhost -d staging |
| |
| # It is common during development, ETL, benchmarking, and so on |
| # to have different databases containing the same table names |
| # but with different contents or layouts. |
| $ impala-shell -i localhost -d parquet_snappy_compression |
| $ impala-shell -i localhost -d parquet_gzip_compression |
| </code></pre> |
| </li> |
| |
| </ol> |
| |
| |
| <p class="p"> |
| <strong class="ph b">To run one or several statements in non-interactive mode:</strong> |
| </p> |
| |
| |
| <p class="p"> You can use all the same connection options as in previous examples. For |
| simplicity, these examples assume that you are logged into one of the |
| Impala daemons. </p> |
| |
| |
| <ol class="ol"> |
| <li class="li"> |
| Construct a statement, or a file containing a sequence of statements, |
| that you want to run in an automated way, without typing or copying |
| and pasting each time. |
| </li> |
| |
| |
| <li class="li"> |
| Invoke <span class="keyword cmdname">impala-shell</span> with the <code class="ph codeph">-q</code> option to run a single statement, or |
| the <code class="ph codeph">-f</code> option to run a sequence of statements from a file. |
| The <span class="keyword cmdname">impala-shell</span> command returns immediately, without going into |
| the interactive interpreter. |
| <pre class="pre codeblock"><code># A utility command that you might run while developing shell scripts |
| # to manipulate HDFS files. |
| $ impala-shell -i localhost -d database_of_interest -q 'show tables' |
| |
| # A sequence of CREATE TABLE, CREATE VIEW, and similar DDL statements |
| # can go into a file to make the setup process repeatable. |
| $ impala-shell -i localhost -d database_of_interest -f recreate_tables.sql |
| </code></pre> |
| </li> |
| |
| </ol> |
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| |
| </div> |
| |
| <div class="related-links"> |
| <div class="familylinks"> |
| <div class="parentlink"><strong>Parent topic:</strong> <a class="link" href="../topics/impala_impala_shell.html">Using the Impala Shell (impala-shell Command)</a></div> |
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