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(topN)</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/sorting-orders.html">String comparators</a></li><li class="navListItem navListItemActive"><a class="navItem" href="/docs/26.0.0/querying/virtual-columns.html">Virtual columns</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/geo.html">Spatial filters</a></li></ul></div></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle collapsible">Configuration<span class="arrow"><svg width="24" height="24" viewBox="0 0 24 24"><path fill="#565656" d="M7.41 15.41L12 10.83l4.59 4.58L18 14l-6-6-6 6z"></path><path d="M0 0h24v24H0z" fill="none"></path></svg></span></h3><ul class="hide"><li class="navListItem"><a class="navItem" href="/docs/26.0.0/configuration/index.html">Configuration reference</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions.html">Extensions</a></li><li class="navListItem"><a class="navItem" 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<blockquote>
<p>Apache Druid supports two query languages: <a href="/docs/26.0.0/querying/sql.html">Druid SQL</a> and <a href="/docs/26.0.0/querying/querying.html">native queries</a>.
This document describes the native
language. For information about functions available in SQL, refer to the
<a href="/docs/26.0.0/querying/sql-scalar.html">SQL documentation</a>.</p>
</blockquote>
<p>Virtual columns are queryable column &quot;views&quot; created from a set of columns during a query.</p>
<p>A virtual column can potentially draw from multiple underlying columns, although a virtual column always presents itself as a single column.</p>
<p>Virtual columns can be referenced by their output names to be used as <a href="/docs/26.0.0/querying/dimensionspecs.html">dimensions</a> or as inputs to <a href="/docs/26.0.0/querying/filters.html">filters</a> and <a href="/docs/26.0.0/querying/aggregations.html">aggregators</a>.</p>
<p>Each Apache Druid query can accept a list of virtual columns as a parameter. The following scan query is provided as an example:</p>
<pre><code class="hljs">{
<span class="hljs-attr">"queryType"</span>: <span class="hljs-string">"scan"</span>,
<span class="hljs-attr">"dataSource"</span>: <span class="hljs-string">"page_data"</span>,
<span class="hljs-attr">"columns"</span>:[],
<span class="hljs-attr">"virtualColumns"</span>: [
{
<span class="hljs-attr">"type"</span>: <span class="hljs-string">"expression"</span>,
<span class="hljs-attr">"name"</span>: <span class="hljs-string">"fooPage"</span>,
<span class="hljs-attr">"expression"</span>: <span class="hljs-string">"concat('foo' + page)"</span>,
<span class="hljs-attr">"outputType"</span>: <span class="hljs-string">"STRING"</span>
},
{
<span class="hljs-attr">"type"</span>: <span class="hljs-string">"expression"</span>,
<span class="hljs-attr">"name"</span>: <span class="hljs-string">"tripleWordCount"</span>,
<span class="hljs-attr">"expression"</span>: <span class="hljs-string">"wordCount * 3"</span>,
<span class="hljs-attr">"outputType"</span>: <span class="hljs-string">"LONG"</span>
}
],
<span class="hljs-attr">"intervals"</span>: [
<span class="hljs-string">"2013-01-01/2019-01-02"</span>
]
}
</code></pre>
<h2><a class="anchor" aria-hidden="true" id="virtual-column-types"></a><a href="#virtual-column-types" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Virtual column types</h2>
<h3><a class="anchor" aria-hidden="true" id="expression-virtual-column"></a><a href="#expression-virtual-column" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Expression virtual column</h3>
<p>Expression virtual columns use Druid's native <a href="/docs/26.0.0/misc/math-expr.html">expression</a> system to allow defining query time
transforms of inputs from one or more columns.</p>
<p>The expression virtual column has the following syntax:</p>
<pre><code class="hljs css language-json">{
<span class="hljs-attr">"type"</span>: <span class="hljs-string">"expression"</span>,
<span class="hljs-attr">"name"</span>: &lt;name of the virtual column&gt;,
<span class="hljs-attr">"expression"</span>: &lt;row expression&gt;,
<span class="hljs-attr">"outputType"</span>: &lt;output value type of expression&gt;
}
</code></pre>
<table>
<thead>
<tr><th>property</th><th>description</th><th>required?</th></tr>
</thead>
<tbody>
<tr><td>type</td><td>Must be <code>&quot;expression&quot;</code> to indicate that this is an expression virtual column.</td><td>yes</td></tr>
<tr><td>name</td><td>The name of the virtual column.</td><td>yes</td></tr>
<tr><td>expression</td><td>An <a href="/docs/26.0.0/misc/math-expr.html">expression</a> that takes a row as input and outputs a value for the virtual column.</td><td>yes</td></tr>
<tr><td>outputType</td><td>The expression's output will be coerced to this type. Can be LONG, FLOAT, DOUBLE, STRING, ARRAY types, or COMPLEX types.</td><td>no, default is FLOAT</td></tr>
</tbody>
</table>
<h3><a class="anchor" aria-hidden="true" id="nested-field-virtual-column"></a><a href="#nested-field-virtual-column" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Nested field virtual column</h3>
<p>The nested field virtual column is an optimized virtual column that can provide direct access into various paths of
a <code>COMPLEX&lt;json&gt;</code> column, including using their indexes.</p>
<p>This virtual column is used for the SQL operators <code>JSON_VALUE</code> (if <code>processFromRaw</code> is set to false) or <code>JSON_QUERY</code>
(if <code>processFromRaw</code> is true), and accepts 'JSONPath' or 'jq' syntax string representations of paths, or a parsed
list of &quot;path parts&quot; in order to determine what should be selected from the column.</p>
<p>You can define a nested field virtual column with any of the following equivalent syntaxes. The examples all produce
the same output value, with each example showing a different way to specify how to access the nested value. The first
is using JSONPath syntax <code>path</code>, the second with a jq <code>path</code>, and the third uses <code>pathParts</code>.</p>
<pre><code class="hljs css language-json"> {
<span class="hljs-attr">"type"</span>: <span class="hljs-string">"nested-field"</span>,
<span class="hljs-attr">"columnName"</span>: <span class="hljs-string">"shipTo"</span>,
<span class="hljs-attr">"outputName"</span>: <span class="hljs-string">"v0"</span>,
<span class="hljs-attr">"expectedType"</span>: <span class="hljs-string">"STRING"</span>,
<span class="hljs-attr">"path"</span>: <span class="hljs-string">"$.phoneNumbers[1].number"</span>
}
</code></pre>
<pre><code class="hljs css language-json"> {
<span class="hljs-attr">"type"</span>: <span class="hljs-string">"nested-field"</span>,
<span class="hljs-attr">"columnName"</span>: <span class="hljs-string">"shipTo"</span>,
<span class="hljs-attr">"outputName"</span>: <span class="hljs-string">"v1"</span>,
<span class="hljs-attr">"expectedType"</span>: <span class="hljs-string">"STRING"</span>,
<span class="hljs-attr">"path"</span>: <span class="hljs-string">".phoneNumbers[1].number"</span>,
<span class="hljs-attr">"useJqSyntax"</span>: <span class="hljs-literal">true</span>
}
</code></pre>
<pre><code class="hljs css language-json"> {
<span class="hljs-attr">"type"</span>: <span class="hljs-string">"nested-field"</span>,
<span class="hljs-attr">"columnName"</span>: <span class="hljs-string">"shipTo"</span>,
<span class="hljs-attr">"outputName"</span>: <span class="hljs-string">"v2"</span>,
<span class="hljs-attr">"expectedType"</span>: <span class="hljs-string">"STRING"</span>,
<span class="hljs-attr">"pathParts"</span>: [
{
<span class="hljs-attr">"type"</span>: <span class="hljs-string">"field"</span>,
<span class="hljs-attr">"field"</span>: <span class="hljs-string">"phoneNumbers"</span>
},
{
<span class="hljs-attr">"type"</span>: <span class="hljs-string">"arrayElement"</span>,
<span class="hljs-attr">"index"</span>: <span class="hljs-number">1</span>
},
{
<span class="hljs-attr">"type"</span>: <span class="hljs-string">"field"</span>,
<span class="hljs-attr">"field"</span>: <span class="hljs-string">"number"</span>
}
]
}
</code></pre>
<table>
<thead>
<tr><th>property</th><th>description</th><th>required?</th></tr>
</thead>
<tbody>
<tr><td>type</td><td>Must be <code>&quot;nested-field&quot;</code> to indicate that this is a nested field virtual column.</td><td>yes</td></tr>
<tr><td>columnName</td><td>The name of the <code>COMPLEX&lt;json&gt;</code> input column.</td><td>yes</td></tr>
<tr><td>outputName</td><td>The name of the virtual column.</td><td>yes</td></tr>
<tr><td>expectedType</td><td>The native Druid output type of the column, Druid will coerce output to this type if it does not match the underlying data. This can be <code>STRING</code>, <code>LONG</code>, <code>FLOAT</code>, <code>DOUBLE</code>, or <code>COMPLEX&lt;json&gt;</code>. Extracting <code>ARRAY</code> types is not yet supported.</td><td>no, default <code>STRING</code></td></tr>
<tr><td>pathParts</td><td>The parsed path parts used to locate the nested values. <code>path</code> will be translated into <code>pathParts</code> internally. One of <code>path</code> or <code>pathParts</code> must be set</td><td>no, if <code>path</code> is defined</td></tr>
<tr><td>processFromRaw</td><td>If set to true, the virtual column will process the &quot;raw&quot; JSON data to extract values rather than using an optimized &quot;literal&quot; value selector. This option allows extracting non-literal values (such as nested JSON objects or arrays) as a <code>COMPLEX&lt;json&gt;</code> at the cost of much slower performance.</td><td>no, default false</td></tr>
<tr><td>path</td><td>'JSONPath' (or 'jq') syntax path. One of <code>path</code> or <code>pathParts</code> must be set.</td><td>no, if <code>pathParts</code> is defined</td></tr>
<tr><td>useJqSyntax</td><td>If true, parse <code>path</code> using 'jq' syntax instead of 'JSONPath'.</td><td>no, default is false</td></tr>
</tbody>
</table>
<h4><a class="anchor" aria-hidden="true" id="nested-path-part"></a><a href="#nested-path-part" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Nested path part</h4>
<p>Specify <code>pathParts</code> as an array of objects that describe each component of the path to traverse. Each object can take the following properties:</p>
<table>
<thead>
<tr><th>property</th><th>description</th><th>required?</th></tr>
</thead>
<tbody>
<tr><td>type</td><td>Must be 'field' or 'arrayElement'. Use <code>field</code> when accessing a specific field in a nested structure. Use <code>arrayElement</code> when accessing a specific integer position of an array (zero based).</td><td>yes</td></tr>
<tr><td>field</td><td>The name of the 'field' in a 'field' <code>type</code> path part</td><td>yes, if <code>type</code> is 'field'</td></tr>
<tr><td>index</td><td>The array element index if <code>type</code> is <code>arrayElement</code></td><td>yes, if <code>type</code> is 'arrayElement'</td></tr>
</tbody>
</table>
<p>See <a href="/docs/26.0.0/querying/nested-columns.html">Nested columns</a> for more information on ingesting and storing nested data.</p>
<h3><a class="anchor" aria-hidden="true" id="list-filtered-virtual-column"></a><a href="#list-filtered-virtual-column" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>List filtered virtual column</h3>
<p>This virtual column provides an alternative way to use
<a href="/docs/26.0.0/querying/dimensionspecs.html#filtered-dimensionspecs">'list filtered' dimension spec</a> as a virtual column. It has optimized
access to the underlying column value indexes that can provide a small performance improvement in some cases.</p>
<pre><code class="hljs css language-json"> {
<span class="hljs-attr">"type"</span>: <span class="hljs-string">"mv-filtered"</span>,
<span class="hljs-attr">"name"</span>: <span class="hljs-string">"filteredDim3"</span>,
<span class="hljs-attr">"delegate"</span>: <span class="hljs-string">"dim3"</span>,
<span class="hljs-attr">"values"</span>: [<span class="hljs-string">"hello"</span>, <span class="hljs-string">"world"</span>],
<span class="hljs-attr">"isAllowList"</span>: <span class="hljs-literal">true</span>
}
</code></pre>
<table>
<thead>
<tr><th>property</th><th>description</th><th>required?</th></tr>
</thead>
<tbody>
<tr><td>type</td><td>Must be <code>&quot;mv-filtered&quot;</code> to indicate that this is a list filtered virtual column.</td><td>yes</td></tr>
<tr><td>name</td><td>The output name of the virtual column</td><td>yes</td></tr>
<tr><td>delegate</td><td>The name of the multi-value STRING input column to filter</td><td>yes</td></tr>
<tr><td>values</td><td>Set of STRING values to allow or deny</td><td>yes</td></tr>
<tr><td>isAllowList</td><td>If true, the output of the virtual column will be limited to the set specified by <code>values</code>, else it will provide all values <em>except</em> those specified.</td><td>No, default true</td></tr>
</tbody>
</table>
</span></div></article></div><div class="docs-prevnext"><a class="docs-prev button" href="/docs/26.0.0/querying/sorting-orders.html"><span class="arrow-prev">โ† </span><span>String comparators</span></a><a class="docs-next button" href="/docs/26.0.0/development/geo.html"><span>Spatial filters</span><span class="arrow-next"> โ†’</span></a></div></div></div><nav class="onPageNav"><ul class="toc-headings"><li><a href="#virtual-column-types">Virtual column types</a><ul class="toc-headings"><li><a href="#expression-virtual-column">Expression virtual column</a></li><li><a href="#nested-field-virtual-column">Nested field virtual column</a></li><li><a href="#list-filtered-virtual-column">List filtered virtual column</a></li></ul></li></ul></nav></div><footer class="nav-footer druid-footer" id="footer"><div class="container"><div class="text-center"><p><a href="/technology">Technology</a>โ€‚ยทโ€‚<a href="/use-cases">Use Cases</a>โ€‚ยทโ€‚<a href="/druid-powered">Powered by Druid</a>โ€‚ยทโ€‚<a href="/docs/26.0.0/">Docs</a>โ€‚ยทโ€‚<a href="/community/">Community</a>โ€‚ยทโ€‚<a href="/downloads.html">Download</a>โ€‚ยทโ€‚<a href="/faq">FAQ</a></p></div><div class="text-center"><a title="Join the user group" href="https://groups.google.com/forum/#!forum/druid-user" target="_blank"><span class="fa fa-comments"></span></a>โ€‚ยทโ€‚<a title="Follow Druid" href="https://twitter.com/druidio" target="_blank"><span class="fab fa-twitter"></span></a>โ€‚ยทโ€‚<a title="Download via Apache" href="https://www.apache.org/dyn/closer.cgi?path=/incubator/druid/{{ site.druid_versions[0].versions[0].version }}/apache-druid-{{ site.druid_versions[0].versions[0].version }}-bin.tar.gz" target="_blank"><span class="fas fa-feather"></span></a>โ€‚ยทโ€‚<a title="GitHub" href="https://github.com/apache/druid" target="_blank"><span class="fab fa-github"></span></a></div><div class="text-center license">Copyright ยฉ 2022 <a href="https://www.apache.org/" target="_blank">Apache Software Foundation</a>.<br/>Except where otherwise noted, licensed under <a rel="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA 4.0</a>.<br/>Apache Druid, Druid, and the Druid logo are either registered trademarks or trademarks of The Apache Software Foundation in the United States and other countries.</div></div></footer></div><script type="text/javascript" src="https://cdn.jsdelivr.net/npm/docsearch.js@2/dist/cdn/docsearch.min.js"></script><script>
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