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href="#frequently-asked-questions"><span>Frequently Asked Questions</span></a></h1><p><strong>How can I identify my version of IoTDB?</strong></p><p>There are several ways to identify the version of IoTDB that you are using:</p><ul><li>Launch IoTDB&#39;s Command Line Interface:</li></ul><div class="language-text line-numbers-mode" data-ext="text" data-title="text"><pre class="language-text"><code>&gt; ./start-cli.sh -p 6667 -pw root -u root -h localhost
 _____       _________  ______   ______    
|_   _|     |  _   _  ||_   _ `.|_   _ \   
  | |   .--.|_/ | | \_|  | | `. \ | |_) |  
  | | / .&#39;`\ \  | |      | |  | | |  __&#39;.  
 _| |_| \__. | _| |_    _| |_.&#39; /_| |__) | 
|_____|&#39;.__.&#39; |_____|  |______.&#39;|_______/  version x.x.x
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><ul><li>Check pom.xml file:</li></ul><div class="language-text line-numbers-mode" data-ext="text" data-title="text"><pre class="language-text"><code>&lt;version&gt;x.x.x&lt;/version&gt;
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></div></div><ul><li>Use JDBC API:</li></ul><div class="language-text line-numbers-mode" data-ext="text" data-title="text"><pre class="language-text"><code>String iotdbVersion = tsfileDatabaseMetadata.getDatabaseProductVersion();
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></div></div><ul><li>Use Command Line Interface:</li></ul><div class="language-text line-numbers-mode" data-ext="text" data-title="text"><pre class="language-text"><code>IoTDB&gt; show version
show version
+---------------+
|version        |
+---------------+
|x.x.x          |
+---------------+
Total line number = 1
It costs 0.241s
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><p><strong>Where can I find IoTDB logs?</strong></p><p>Suppose your root directory is:</p><div class="language-text line-numbers-mode" data-ext="text" data-title="text"><pre class="language-text"><code>$ pwd
/workspace/iotdb

$ ls -l
server/
cli/
pom.xml
Readme.md
...
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><p>Let <code>$IOTDB_HOME = /workspace/iotdb/server/target/iotdb-server-{project.version}</code></p><p>Let <code>$IOTDB_CLI_HOME = /workspace/iotdb/cli/target/iotdb-cli-{project.version}</code></p><p>By default settings, the logs are stored under <code>IOTDB_HOME/logs</code>. You can change log level and storage path by configuring <code>logback.xml</code> under <code>IOTDB_HOME/conf</code>.</p><p><strong>Where can I find IoTDB data files?</strong></p><p>By default settings, the data files (including tsfile, metadata, and WAL files) are stored under <code>IOTDB_HOME/data</code>.</p><p><strong>How do I know how many time series are stored in IoTDB?</strong></p><p>Use IoTDB&#39;s Command Line Interface:</p><div class="language-text line-numbers-mode" data-ext="text" data-title="text"><pre class="language-text"><code>IoTDB&gt; show timeseries root
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></div></div><p>In the result, there is a statement shows <code>Total timeseries number</code>, this number is the timeseries number in IoTDB.</p><p>In the current version, IoTDB supports querying the number of time series. Use IoTDB&#39;s Command Line Interface:</p><div class="language-text line-numbers-mode" data-ext="text" data-title="text"><pre class="language-text"><code>IoTDB&gt; count timeseries root
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></div></div><p>If you are using Linux, you can use the following shell command:</p><div class="language-text line-numbers-mode" data-ext="text" data-title="text"><pre class="language-text"><code>&gt; grep &quot;0,root&quot; $IOTDB_HOME/data/system/schema/mlog.txt |  wc -l
&gt;   6
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div></div></div><p><strong>Can I use Hadoop and Spark to read TsFile in IoTDB?</strong></p><p>Yes. IoTDB has intense integration with Open Source Ecosystem. IoTDB supports <a href="https://github.com/apache/iotdb/tree/master/hadoop" target="_blank" rel="noopener noreferrer">Hadoop<span><svg class="external-link-icon" xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path><polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg><span class="external-link-icon-sr-only">open in new window</span></span></a>, <a href="https://github.com/apache/iotdb/tree/master/spark" target="_blank" rel="noopener noreferrer">Spark<span><svg class="external-link-icon" xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path><polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg><span class="external-link-icon-sr-only">open in new window</span></span></a> and <a href="https://github.com/apache/iotdb/tree/master/grafana" target="_blank" rel="noopener noreferrer">Grafana<span><svg class="external-link-icon" xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path><polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg><span class="external-link-icon-sr-only">open in new window</span></span></a> visualization tool.</p><p><strong>How does IoTDB handle duplicate points?</strong></p><p>A data point is uniquely identified by a full time series path (e.g. <code>root.vehicle.d0.s0</code>) and timestamp. If you submit a new point with the same path and timestamp as an existing point, IoTDB updates the value of this point instead of inserting a new point.</p><p><strong>How can I tell what type of the specific timeseries?</strong></p><p>Use <code>SHOW TIMESERIES &lt;timeseries path&gt;</code> SQL in IoTDB&#39;s Command Line Interface:</p><p>For example, if you want to know the type of all timeseries, the &lt;timeseries path&gt; should be <code>root</code>. The statement will be:</p><div class="language-text line-numbers-mode" data-ext="text" data-title="text"><pre class="language-text"><code>IoTDB&gt; show timeseries root
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></div></div><p>If you want to query specific sensor, you can replace the &lt;timeseries path&gt; with the sensor name. For example:</p><div class="language-text line-numbers-mode" data-ext="text" data-title="text"><pre class="language-text"><code>IoTDB&gt; show timeseries root.fit.d1.s1
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></div></div><p>Otherwise, you can also use wildcard in timeseries path:</p><div class="language-text line-numbers-mode" data-ext="text" data-title="text"><pre class="language-text"><code>IoTDB&gt; show timeseries root.fit.d1.*
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></div></div><p><strong>How can I change IoTDB&#39;s Cli time display format?</strong></p><p>The default IoTDB&#39;s Cli time display format is readable (e.g. <code>1970-01-01T08:00:00.001</code>), if you want to display time in timestamp type or other readable format, add parameter <code>-disableISO8601</code> in start command:</p><div class="language-text line-numbers-mode" data-ext="text" data-title="text"><pre class="language-text"><code>&gt; $IOTDB_CLI_HOME/sbin/start-cli.sh -h 127.0.0.1 -p 6667 -u root -pw root -disableISO8601
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