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class="container padding-top--md padding-bottom--lg"><div class="row"><div class="col docItemCol_VOVn"><div class="docItemContainer_Djhp"><article><nav class="theme-doc-breadcrumbs breadcrumbsContainer_Z_bl" aria-label="Breadcrumbs"><ul class="breadcrumbs" itemscope="" itemtype="https://schema.org/BreadcrumbList"><li class="breadcrumbs__item"><a aria-label="Home page" class="breadcrumbs__link" href="/"><svg viewBox="0 0 24 24" class="breadcrumbHomeIcon_YNFT"><path d="M10 19v-5h4v5c0 .55.45 1 1 1h3c.55 0 1-.45 1-1v-7h1.7c.46 0 .68-.57.33-.87L12.67 3.6c-.38-.34-.96-.34-1.34 0l-8.36 7.53c-.34.3-.13.87.33.87H5v7c0 .55.45 1 1 1h3c.55 0 1-.45 1-1z" fill="currentColor"></path></svg></a></li><li class="breadcrumbs__item"><span class="breadcrumbs__link">Ingestion</span><meta itemprop="position" content="1"></li><li itemscope="" itemprop="itemListElement" itemtype="https://schema.org/ListItem" class="breadcrumbs__item breadcrumbs__item--active"><span class="breadcrumbs__link" itemprop="name">Data model</span><meta itemprop="position" content="2"></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>Druid data model</h1></header><p>Druid stores data in datasources, which are similar to tables in a traditional relational database management system (RDBMS). Druid's data model shares similarities with both relational and timeseries data models.</p><h2 class="anchor anchorWithStickyNavbar_LWe7" id="primary-timestamp">Primary timestamp<a href="#primary-timestamp" class="hash-link" aria-label="Direct link to Primary timestamp" title="Direct link to Primary timestamp"></a></h2><p>Druid schemas must always include a primary timestamp. Druid uses the primary timestamp to <a href="/docs/26.0.0/ingestion/partitioning">partition and sort</a> your data. Druid uses the primary timestamp to rapidly identify and retrieve data within the time range of queries. Druid also uses the primary timestamp column |
| for time-based <a href="/docs/26.0.0/data-management/">data management operations</a> such as dropping time chunks, overwriting time chunks, and time-based retention rules.</p><p>Druid parses the primary timestamp based on the <a href="/docs/26.0.0/ingestion/ingestion-spec#timestampspec"><code>timestampSpec</code></a> configuration at ingestion time. Regardless of the source field for the primary timestamp, Druid always stores the timestamp in the <code>__time</code> column in your Druid datasource.</p><p>You can control other important operations that are based on the primary timestamp in the |
| <a href="/docs/26.0.0/ingestion/ingestion-spec#granularityspec"><code>granularitySpec</code></a>. If you have more than one timestamp column, you can store the others as |
| <a href="/docs/26.0.0/ingestion/schema-design#secondary-timestamps">secondary timestamps</a>.</p><h2 class="anchor anchorWithStickyNavbar_LWe7" id="dimensions">Dimensions<a href="#dimensions" class="hash-link" aria-label="Direct link to Dimensions" title="Direct link to Dimensions"></a></h2><p>Dimensions are columns that Druid stores "as-is". You can use dimensions for any purpose. For example, you can group, filter, or apply aggregators to dimensions at query time when necessary.</p><p>If you disable <a href="/docs/26.0.0/ingestion/rollup">rollup</a>, then Druid treats the set of |
| dimensions like a set of columns to ingest. The dimensions behave exactly as you would expect from any database that does not support a rollup feature.</p><p>At ingestion time, you configure dimensions in the <a href="/docs/26.0.0/ingestion/ingestion-spec#dimensionsspec"><code>dimensionsSpec</code></a>.</p><h2 class="anchor anchorWithStickyNavbar_LWe7" id="metrics">Metrics<a href="#metrics" class="hash-link" aria-label="Direct link to Metrics" title="Direct link to Metrics"></a></h2><p>Metrics are columns that Druid stores in an aggregated form. Metrics are most useful when you enable <a href="/docs/26.0.0/ingestion/rollup">rollup</a>. If you specify a metric, you can apply an aggregation function to each row during ingestion. This |
| has the following benefits:</p><p>Rollup is a form of aggregation that collapses dimensions while aggregating the values in the metrics, that is, it collapses rows but retains its summary information."</p><ul><li><p><a href="/docs/26.0.0/ingestion/rollup">Rollup</a> is a form of aggregation that combines multiple rows with the same timestamp value and dimension values. For example, the <a href="/docs/26.0.0/tutorials/tutorial-rollup">rollup tutorial</a> demonstrates using rollup to collapse netflow data to a single row per <code>(minute, srcIP, dstIP)</code> tuple, while retaining aggregate information about total packet and byte counts.</p></li><li><p>Druid can compute some aggregators, especially approximate ones, more quickly at query time if they are partially computed at ingestion time, including data that has not been rolled up.</p><p>At ingestion time, you configure Metrics in the <a href="/docs/26.0.0/ingestion/ingestion-spec#metricsspec"><code>metricsSpec</code></a>.</p></li></ul></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/ingestion/data-formats"><div class="pagination-nav__sublabel">Previous</div><div class="pagination-nav__label">Data formats</div></a><a class="pagination-nav__link pagination-nav__link--next" href="/docs/26.0.0/ingestion/rollup"><div class="pagination-nav__sublabel">Next</div><div class="pagination-nav__label">Data rollup</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="#primary-timestamp" class="table-of-contents__link toc-highlight">Primary timestamp</a></li><li><a href="#dimensions" class="table-of-contents__link toc-highlight">Dimensions</a></li><li><a href="#metrics" class="table-of-contents__link toc-highlight">Metrics</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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