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class="breadcrumbs__link">Druid SQL</span><meta itemprop="position" content="2"></li><li itemscope="" itemprop="itemListElement" itemtype="https://schema.org/ListItem" class="breadcrumbs__item breadcrumbs__item--active"><span class="breadcrumbs__link" itemprop="name">SQL data types</span><meta itemprop="position" content="3"></li></ul></nav><div class="tocCollapsible_ETCw theme-doc-toc-mobile tocMobile_ITEo"><button type="button" class="clean-btn tocCollapsibleButton_TO0P">On this page</button></div><div class="theme-doc-markdown markdown"><header><h1>SQL data types</h1></header><blockquote><p>Apache Druid supports two query languages: Druid SQL and <a href="/docs/26.0.0/querying/">native queries</a>. |
| This document describes the SQL language.</p></blockquote><p>Columns in Druid are associated with a specific data type. This topic describes supported data types in <a href="/docs/26.0.0/querying/sql">Druid SQL</a>. </p><h2 class="anchor anchorWithStickyNavbar_LWe7" id="standard-types">Standard types<a href="#standard-types" class="hash-link" aria-label="Direct link to Standard types" title="Direct link to Standard types"></a></h2><p>Druid natively supports the following basic column types:</p><ul><li>LONG: (64 bit signed int)</li><li>FLOAT (32 bit float)</li><li>DOUBLE: (64 bit float)</li><li>STRING: (UTF-8 encoded strings and string arrays)</li><li>COMPLEX: non-standard data types, such as nested JSON, hyperUnique and approxHistogram, and DataSketches</li><li>ARRAY: arrays composed of any of these types</li></ul><p>Timestamps (including the <code>__time</code> column) are treated by Druid as longs, with the value being the number of |
| milliseconds since 1970-01-01 00:00:00 UTC, not counting leap seconds. Therefore, timestamps in Druid do not carry any |
| timezone information, but only carry information about the exact moment in time they represent. See the |
| <a href="/docs/26.0.0/querying/sql-scalar#date-and-time-functions">Time functions</a> section for more information about timestamp handling.</p><p>Casts between two SQL types with the same Druid runtime type (see below table) have no effect, other than exceptions |
| noted in the table. Casts between two SQL types that have different Druid runtime types generate a runtime cast in |
| Druid. If a value cannot be cast to the target type, as in <code>CAST('foo' AS BIGINT)</code>, Druid either substitutes a default |
| value (when <code>druid.generic.useDefaultValueForNull = true</code>, the default mode), or substitutes <a href="#null-values">NULL</a> (when |
| <code>druid.generic.useDefaultValueForNull = false</code>). NULL values cast to non-nullable types are also substituted with a |
| default value. For example, if <code>druid.generic.useDefaultValueForNull = true</code>, a null VARCHAR cast to BIGINT is converted |
| to a zero.</p><p>The following table describes how Druid maps SQL types onto native types when running queries.</p><table><thead><tr><th>SQL type</th><th>Druid runtime type</th><th>Default value<sup>*</sup></th><th>Notes</th></tr></thead><tbody><tr><td>CHAR</td><td>STRING</td><td><code>''</code></td><td></td></tr><tr><td>VARCHAR</td><td>STRING</td><td><code>''</code></td><td>Druid STRING columns are reported as VARCHAR. Can include <a href="#multi-value-strings">multi-value strings</a> as well.</td></tr><tr><td>DECIMAL</td><td>DOUBLE</td><td><code>0.0</code></td><td>DECIMAL uses floating point, not fixed point math</td></tr><tr><td>FLOAT</td><td>FLOAT</td><td><code>0.0</code></td><td>Druid FLOAT columns are reported as FLOAT</td></tr><tr><td>REAL</td><td>DOUBLE</td><td><code>0.0</code></td><td></td></tr><tr><td>DOUBLE</td><td>DOUBLE</td><td><code>0.0</code></td><td>Druid DOUBLE columns are reported as DOUBLE</td></tr><tr><td>BOOLEAN</td><td>LONG</td><td><code>false</code></td><td></td></tr><tr><td>TINYINT</td><td>LONG</td><td><code>0</code></td><td></td></tr><tr><td>SMALLINT</td><td>LONG</td><td><code>0</code></td><td></td></tr><tr><td>INTEGER</td><td>LONG</td><td><code>0</code></td><td></td></tr><tr><td>BIGINT</td><td>LONG</td><td><code>0</code></td><td>Druid LONG columns (except <code>__time</code>) are reported as BIGINT</td></tr><tr><td>TIMESTAMP</td><td>LONG</td><td><code>0</code>, meaning 1970-01-01 00:00:00 UTC</td><td>Druid's <code>__time</code> column is reported as TIMESTAMP. Casts between string and timestamp types assume standard SQL formatting, e.g. <code>2000-01-02 03:04:05</code>, <em>not</em> ISO8601 formatting. For handling other formats, use one of the <a href="/docs/26.0.0/querying/sql-scalar#date-and-time-functions">time functions</a>.</td></tr><tr><td>DATE</td><td>LONG</td><td><code>0</code>, meaning 1970-01-01</td><td>Casting TIMESTAMP to DATE rounds down the timestamp to the nearest day. Casts between string and date types assume standard SQL formatting, e.g. <code>2000-01-02</code>. For handling other formats, use one of the <a href="/docs/26.0.0/querying/sql-scalar#date-and-time-functions">time functions</a>.</td></tr><tr><td>ARRAY</td><td>ARRAY</td><td><code>NULL</code></td><td>Druid native array types work as SQL arrays, and multi-value strings can be converted to arrays. See the <a href="#arrays"><code>ARRAY</code> details</a>.</td></tr><tr><td>OTHER</td><td>COMPLEX</td><td>none</td><td>May represent various Druid column types such as hyperUnique, approxHistogram, etc.</td></tr></tbody></table><sup>*</sup> Default value applies if `druid.generic.useDefaultValueForNull = true` (the default mode). Otherwise, the default value is `NULL` for all types.<h2 class="anchor anchorWithStickyNavbar_LWe7" id="multi-value-strings">Multi-value strings<a href="#multi-value-strings" class="hash-link" aria-label="Direct link to Multi-value strings" title="Direct link to Multi-value strings"></a></h2><p>Druid's native type system allows strings to potentially have multiple values. These |
| <a href="/docs/26.0.0/querying/multi-value-dimensions">multi-value string dimensions</a> are reported in SQL as <code>VARCHAR</code> typed, and can be |
| syntactically used like any other <code>VARCHAR</code>. Regular string functions that refer to multi-value string dimensions are |
| applied to all values for each row individually. Multi-value string dimensions can also be treated as arrays via special |
| <a href="/docs/26.0.0/querying/sql-multivalue-string-functions">multi-value string functions</a>, which can perform powerful array-aware operations, but retain |
| their <code>VARCHAR</code> typing and behavior.</p><p>Grouping by a multi-value expression observes the native Druid multi-value aggregation behavior, which is similar to |
| an implicit SQL <code>UNNEST</code>. Refer to the documentation on <a href="/docs/26.0.0/querying/multi-value-dimensions">multi-value string dimensions</a> |
| for additional details.</p><blockquote><p>Because multi-value dimensions are treated by the SQL planner as <code>VARCHAR</code>, there are some inconsistencies between how |
| they are handled in Druid SQL and in native queries. For example, expressions involving multi-value dimensions may be |
| incorrectly optimized by the Druid SQL planner: <code>multi_val_dim = 'a' AND multi_val_dim = 'b'</code> is optimized to |
| <code>false</code>, even though it is possible for a single row to have both "a" and "b" as values for <code>multi_val_dim</code>. The |
| SQL behavior of multi-value dimensions may change in a future release to more closely align with their behavior |
| in native queries, but the <a href="/docs/26.0.0/querying/sql-multivalue-string-functions">multi-value string functions</a> should be able to provide |
| nearly all possible native functionality.</p></blockquote><h2 class="anchor anchorWithStickyNavbar_LWe7" id="arrays">Arrays<a href="#arrays" class="hash-link" aria-label="Direct link to Arrays" title="Direct link to Arrays"></a></h2><p>Druid supports <code>ARRAY</code> types constructed at query time, though it currently lacks the ability to store them in |
| segments. <code>ARRAY</code> types behave as standard SQL arrays, where results are grouped by matching entire arrays. This is in |
| contrast to the implicit <code>UNNEST</code> that occurs when grouping on multi-value dimensions directly or when used with the |
| multi-value functions. You can convert multi-value dimensions to standard SQL arrays either by explicitly by converting |
| them with <code>MV_TO_ARRAY</code> or implicitly when used within the <a href="/docs/26.0.0/querying/sql-array-functions">array functions</a>. Arrays may |
| also be constructed from multiple columns using the array functions.</p><h2 class="anchor anchorWithStickyNavbar_LWe7" id="multi-value-strings-behavior">Multi-value strings behavior<a href="#multi-value-strings-behavior" class="hash-link" aria-label="Direct link to Multi-value strings behavior" title="Direct link to Multi-value strings behavior"></a></h2><p>The behavior of Druid <a href="/docs/26.0.0/querying/multi-value-dimensions">multi-value string dimensions</a> varies depending on the context of |
| their usage.</p><p>When used with standard <code>VARCHAR</code> functions which expect a single input value per row, such as <code>CONCAT</code>, Druid will map |
| the function across all values in the row. If the row is null or empty, the function receives <code>NULL</code> as its input.</p><p>When used with the explicit <a href="/docs/26.0.0/querying/sql-multivalue-string-functions">multi-value string functions</a>, Druid processes the |
| row values as if they were <code>ARRAY</code> typed. Any operations which produce null and empty rows are distinguished as |
| separate values (unlike implicit mapping behavior). These multi-value string functions, typically denoted with an <code>MV_</code> |
| prefix, retain their <code>VARCHAR</code> type after the computation is complete. Note that Druid multi-value columns do <em>not</em> |
| distinguish between empty and null rows. An empty row will never appear natively as input to a multi-valued function, |
| but any multi-value function which manipulates the array form of the value may produce an empty array, which is handled |
| separately while processing.</p><blockquote><p>Do not mix the usage of multi-value functions and normal scalar functions within the same expression, as the planner will be unable |
| to determine how to properly process the value given its ambiguous usage. A multi-value string must be treated consistently within |
| an expression.</p></blockquote><p>When converted to <code>ARRAY</code> or used with <a href="/docs/26.0.0/querying/sql-array-functions">array functions</a>, multi-value strings behave as standard SQL arrays and can no longer |
| be manipulated with non-array functions.</p><p>Druid serializes multi-value <code>VARCHAR</code> results as a JSON string of the array, if grouping was not applied on the value. |
| If the value was grouped, due to the implicit <code>UNNEST</code> behavior, all results will always be standard single value |
| <code>VARCHAR</code>. <code>ARRAY</code> typed results will be serialized into stringified JSON arrays if the context parameter |
| <code>sqlStringifyArrays</code> is set, otherwise they remain in their array format.</p><h2 class="anchor anchorWithStickyNavbar_LWe7" id="null-values">NULL values<a href="#null-values" class="hash-link" aria-label="Direct link to NULL values" title="Direct link to NULL values"></a></h2><p>The <a href="/docs/26.0.0/configuration/#sql-compatible-null-handling"><code>druid.generic.useDefaultValueForNull</code></a> |
| runtime property controls Druid's NULL handling mode. For the most SQL compliant behavior, set this to <code>false</code>.</p><p>When <code>druid.generic.useDefaultValueForNull = true</code> (the default mode), Druid treats NULLs and empty strings |
| interchangeably, rather than according to the SQL standard. In this mode Druid SQL only has partial support for NULLs. |
| For example, the expressions <code>col IS NULL</code> and <code>col = ''</code> are equivalent, and both evaluate to true if <code>col</code> |
| contains an empty string. Similarly, the expression <code>COALESCE(col1, col2)</code> returns <code>col2</code> if <code>col1</code> is an empty |
| string. While the <code>COUNT(*)</code> aggregator counts all rows, the <code>COUNT(expr)</code> aggregator counts the number of rows |
| where <code>expr</code> is neither null nor the empty string. Numeric columns in this mode are not nullable; any null or missing |
| values are treated as zeroes.</p><p>When <code>druid.generic.useDefaultValueForNull = false</code>, NULLs are treated more closely to the SQL standard. In this mode, |
| numeric NULL is permitted, and NULLs and empty strings are no longer treated as interchangeable. This property |
| affects both storage and querying, and must be set on all Druid service types to be available at both ingestion time |
| and query time. There is some overhead associated with the ability to handle NULLs; see |
| the <a href="/docs/26.0.0/design/segments#handling-null-values">segment internals</a> documentation for more details.</p><h2 class="anchor anchorWithStickyNavbar_LWe7" id="boolean-logic">Boolean logic<a href="#boolean-logic" class="hash-link" aria-label="Direct link to Boolean logic" title="Direct link to Boolean logic"></a></h2><p>The <a href="/docs/26.0.0/configuration/#expression-processing-configurations"><code>druid.expressions.useStrictBooleans</code></a> |
| runtime property controls Druid's boolean logic mode. For the most SQL compliant behavior, set this to <code>true</code>.</p><p>When <code>druid.expressions.useStrictBooleans = false</code> (the default mode), Druid uses two-valued logic.</p><p>When <code>druid.expressions.useStrictBooleans = true</code>, Druid uses three-valued logic for |
| <a href="/docs/26.0.0/misc/math-expr">expressions</a> evaluation, such as <code>expression</code> virtual columns or <code>expression</code> filters. |
| However, even in this mode, Druid uses two-valued logic for filter types other than <code>expression</code>.</p><h2 class="anchor anchorWithStickyNavbar_LWe7" id="nested-columns">Nested columns<a href="#nested-columns" class="hash-link" aria-label="Direct link to Nested columns" title="Direct link to Nested columns"></a></h2><p>Druid supports storing nested data structures in segments using the native <code>COMPLEX<json></code> type. See <a href="/docs/26.0.0/querying/nested-columns">Nested columns</a> for more information.</p><p>You can interact with nested data using <a href="/docs/26.0.0/querying/sql-json-functions">JSON functions</a>, which can extract nested values, parse from string, serialize to string, and create new <code>COMPLEX<json></code> structures.</p><p><code>COMPLEX</code> types have limited functionality outside the specialized functions that use them, so their behavior is undefined when:</p><ul><li>Grouping on complex values.</li><li>Filtering directly on complex values, such as <code>WHERE json is NULL</code>.</li><li>Used as inputs to aggregators without specialized handling for a specific complex type.</li></ul><p>In many cases, functions are provided to translate <code>COMPLEX</code> value types to <code>STRING</code>, which serves as a workaround solution until <code>COMPLEX</code> type functionality can be improved.</p></div></article><nav class="pagination-nav docusaurus-mt-lg" aria-label="Docs pages"><a class="pagination-nav__link pagination-nav__link--prev" href="/docs/26.0.0/querying/sql"><div class="pagination-nav__sublabel">Previous</div><div class="pagination-nav__label">Overview and syntax</div></a><a class="pagination-nav__link pagination-nav__link--next" href="/docs/26.0.0/querying/sql-operators"><div class="pagination-nav__sublabel">Next</div><div class="pagination-nav__label">Operators</div></a></nav></div></div><div class="col col--3"><div class="tableOfContents_bqdL thin-scrollbar theme-doc-toc-desktop"><ul class="table-of-contents table-of-contents__left-border"><li><a href="#standard-types" class="table-of-contents__link toc-highlight">Standard types</a></li><li><a href="#multi-value-strings" class="table-of-contents__link toc-highlight">Multi-value strings</a></li><li><a href="#arrays" class="table-of-contents__link toc-highlight">Arrays</a></li><li><a href="#multi-value-strings-behavior" class="table-of-contents__link toc-highlight">Multi-value strings behavior</a></li><li><a href="#null-values" class="table-of-contents__link toc-highlight">NULL values</a></li><li><a href="#boolean-logic" class="table-of-contents__link toc-highlight">Boolean logic</a></li><li><a href="#nested-columns" class="table-of-contents__link toc-highlight">Nested columns</a></li></ul></div></div></div></div></main></div></div><footer class="footer"><div class="container container-fluid"><div class="footer__bottom text--center"><div class="margin-bottom--sm"><img src="/img/favicon.png" class="themedImage_ToTc themedImage--light_HNdA footer__logo"><img src="/img/favicon.png" class="themedImage_ToTc themedImage--dark_i4oU footer__logo"></div><div class="footer__copyright">Copyright © 2023 Apache Software Foundation. Except where otherwise noted, licensed under CC BY-SA 4.0. 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></div></footer></div> |
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