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<blockquote>
<p>Apache Druid supports two query languages: Druid SQL and <a href="/docs/latest/querying/querying.html">native queries</a>.
This document describes the SQL language.</p>
</blockquote>
<p>Druid supports string dimensions containing multiple values.
This page describes the operations you can perform on multi-value string dimensions using <a href="/docs/latest/querying/sql.html">Druid SQL</a>.
See <a href="/docs/latest/querying/sql-data-types.html#multi-value-strings">SQL multi-value strings</a> and native <a href="/docs/latest/querying/multi-value-dimensions.html">Multi-value dimensions</a> for more information.</p>
<p>All array references in the multi-value string function documentation can refer to multi-value string columns or
<code>ARRAY</code> types. These functions are largely identical to the <a href="/docs/latest/querying/sql-array-functions.html">array functions</a>, but use
<code>VARCHAR</code> types and behavior. Multi-value strings can also be converted to <code>ARRAY</code> types using <code>MV_TO_ARRAY</code>. For
additional details about <code>ARRAY</code> types, see <a href="/docs/latest/querying/sql-data-types.html#arrays"><code>ARRAY</code> data type documentation</a>.</p>
<table>
<thead>
<tr><th>Function</th><th>Description</th></tr>
</thead>
<tbody>
<tr><td><code>MV_FILTER_ONLY(expr, arr)</code></td><td>Filters multi-value <code>expr</code> to include only values contained in array <code>arr</code>.</td></tr>
<tr><td><code>MV_FILTER_NONE(expr, arr)</code></td><td>Filters multi-value <code>expr</code> to include no values contained in array <code>arr</code>.</td></tr>
<tr><td><code>MV_LENGTH(arr)</code></td><td>Returns length of the array expression.</td></tr>
<tr><td><code>MV_OFFSET(arr, long)</code></td><td>Returns the array element at the 0-based index supplied, or null for an out of range index.</td></tr>
<tr><td><code>MV_ORDINAL(arr, long)</code></td><td>Returns the array element at the 1-based index supplied, or null for an out of range index.</td></tr>
<tr><td><code>MV_CONTAINS(arr, expr)</code></td><td>If <code>expr</code> is a scalar type, returns 1 if <code>arr</code> contains <code>expr</code>. If <code>expr</code> is an array, returns 1 if <code>arr</code> contains all elements of <code>expr</code>. Otherwise returns 0.</td></tr>
<tr><td><code>MV_OVERLAP(arr1, arr2)</code></td><td>Returns 1 if <code>arr1</code> and <code>arr2</code> have any elements in common, else 0.</td></tr>
<tr><td><code>MV_OFFSET_OF(arr, expr)</code></td><td>Returns the 0-based index of the first occurrence of <code>expr</code> in the array. If no matching elements exist in the array, returns <code>-1</code> or <code>null</code> if <code>druid.generic.useDefaultValueForNull=false</code>.</td></tr>
<tr><td><code>MV_ORDINAL_OF(arr, expr)</code></td><td>Returns the 1-based index of the first occurrence of <code>expr</code> in the array. If no matching elements exist in the array, returns <code>-1</code> or <code>null</code> if <code>druid.generic.useDefaultValueForNull=false</code>.</td></tr>
<tr><td><code>MV_PREPEND(expr, arr)</code></td><td>Adds <code>expr</code> to <code>arr</code> at the beginning, the resulting array type determined by the type of the array.</td></tr>
<tr><td><code>MV_APPEND(arr1, expr)</code></td><td>Appends <code>expr</code> to <code>arr</code>, the resulting array type determined by the type of the first array.</td></tr>
<tr><td><code>MV_CONCAT(arr1, arr2)</code></td><td>Concatenates <code>arr2</code> to <code>arr1</code>. The resulting array type is determined by the type of <code>arr1</code>.</td></tr>
<tr><td><code>MV_SLICE(arr, start, end)</code></td><td>Returns the subarray of <code>arr</code> from the 0-based index start(inclusive) to end(exclusive), or <code>null</code>, if start is less than 0, greater than length of arr or greater than end.</td></tr>
<tr><td><code>MV_TO_STRING(arr, str)</code></td><td>Joins all elements of <code>arr</code> by the delimiter specified by <code>str</code>.</td></tr>
<tr><td><code>STRING_TO_MV(str1, str2)</code></td><td>Splits <code>str1</code> into an array on the delimiter specified by <code>str2</code>.</td></tr>
<tr><td><code>MV_TO_ARRAY(str)</code></td><td>Converts a multi-value string from a <code>VARCHAR</code> to a <code>VARCHAR ARRAY</code>.</td></tr>
</tbody>
</table>
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