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    <link rel="alternate" hreflang="en-us" href="https://iotdb.apache.org/UserGuide/V0.13.x/Operate-Metadata/TTL.html"><meta property="og:url" content="https://iotdb.apache.org/zh/UserGuide/V0.13.x/Operate-Metadata/TTL.html"><meta property="og:site_name" content="IoTDB Website"><meta property="og:description" content="数据存活时间（TTL） IoTDB 支持对存储组级别设置数据存活时间（TTL），这使得 IoTDB 可以定期、自动地删除一定时间之前的数据。合理使用 TTL 可以帮助您控制 IoTDB 占用的总磁盘空间以避免出现磁盘写满等异常。并且，随着文件数量的增多，查询性能往往随之下降， 内存占用也会有所提高。及时地删除一些较老的文件有助于使查询性能维持在一个较高..."><meta property="og:type" content="article"><meta property="og:locale" content="zh-CN"><meta property="og:locale:alternate" content="en-US"><meta property="og:updated_time" content="2023-07-10T03:11:17.000Z"><meta property="article:modified_time" content="2023-07-10T03:11:17.000Z"><script type="application/ld+json">{"@context":"https://schema.org","@type":"Article","headline":"","image":[""],"dateModified":"2023-07-10T03:11:17.000Z","author":[]}</script><link rel="icon" href="/favicon.ico"><meta name="Description" content="Apache IoTDB: Time Series Database for IoT"><meta name="Keywords" content="TSDB, time series, time series database, IoTDB, IoT database, IoT data management,时序数据库, 时间序列管理, IoTDB, 物联网数据库, 实时数据库, 物联网数据管理, 物联网数据"><meta name="baidu-site-verification" content="wfKETzB3OT"><meta name="google-site-verification" content="mZWAoRY0yj_HAr-s47zHCGHzx5Ju-RVm5wDbPnwQYFo"><script type="text/javascript">
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       </script><title>IoTDB Website</title><meta name="description" content="数据存活时间（TTL） IoTDB 支持对存储组级别设置数据存活时间（TTL），这使得 IoTDB 可以定期、自动地删除一定时间之前的数据。合理使用 TTL 可以帮助您控制 IoTDB 占用的总磁盘空间以避免出现磁盘写满等异常。并且，随着文件数量的增多，查询性能往往随之下降， 内存占用也会有所提高。及时地删除一些较老的文件有助于使查询性能维持在一个较高...">
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364.8h-44.8V128c0-17.067-14.933-32-32-32H281.6c-17.067 0-32 14.933-32 32v236.8h-44.8C145.067 364.8 96 413.867 96 473.6v192c0 59.733 49.067 108.8 108.8 108.8h44.8V896c0 17.067 14.933 32 32 32h460.8c17.067 0 32-14.933 32-32V774.4h44.8c59.733 0 108.8-49.067 108.8-108.8v-192c0-59.733-49.067-108.8-108.8-108.8zM313.6 160h396.8v204.8H313.6V160zm396.8 704H313.6V620.8h396.8V864zM864 665.6c0 25.6-19.2 44.8-44.8 44.8h-44.8V588.8c0-17.067-14.933-32-32-32H281.6c-17.067 0-32 14.933-32 32v121.6h-44.8c-25.6 0-44.8-19.2-44.8-44.8v-192c0-25.6 19.2-44.8 44.8-44.8h614.4c25.6 0 44.8 19.2 44.8 44.8v192z"></path></svg></button><div class="arrow end"></div></div><div class="vp-toc-wrapper"><ul class="vp-toc-list"><!--[--><li class="vp-toc-item"><a class="route-link vp-toc-link level2" href="#数据存活时间-ttl">数据存活时间（TTL）</a></li><li><ul class="vp-toc-list"><!--[--><li class="vp-toc-item"><a class="route-link vp-toc-link level3" href="#设置-ttl">设置 TTL</a></li><!----><!--]--><!--[--><li class="vp-toc-item"><a class="route-link vp-toc-link level3" href="#取消-ttl">取消 TTL</a></li><!----><!--]--><!--[--><li class="vp-toc-item"><a class="route-link vp-toc-link level3" href="#显示-ttl">显示 TTL</a></li><!----><!--]--></ul></li><!--]--></ul><div class="vp-toc-marker" style="top:-1.7rem;"></div></div><!--[--><!----><!--]--></aside></div><!--[--><!----><!--]--><div class="theme-hope-content"><h2 id="数据存活时间-ttl" tabindex="-1"><a class="header-anchor" href="#数据存活时间-ttl"><span>数据存活时间（TTL）</span></a></h2><p>IoTDB 支持对存储组级别设置数据存活时间（TTL），这使得 IoTDB 可以定期、自动地删除一定时间之前的数据。合理使用 TTL<br> 可以帮助您控制 IoTDB 占用的总磁盘空间以避免出现磁盘写满等异常。并且，随着文件数量的增多，查询性能往往随之下降，<br> 内存占用也会有所提高。及时地删除一些较老的文件有助于使查询性能维持在一个较高的水平和减少内存资源的占用。</p><h3 id="设置-ttl" tabindex="-1"><a class="header-anchor" href="#设置-ttl"><span>设置 TTL</span></a></h3><p>设置 TTL 的 SQL 语句如下所示：</p><div class="language-text line-numbers-mode" data-ext="text" data-title="text"><pre class="language-text"><code>IoTDB&gt; set ttl to root.ln 3600000
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></div></div><p>这个例子表示在<code>root.ln</code>存储组中，只有最近一个小时的数据将会保存，旧数据会被移除或不可见。</p><h3 id="取消-ttl" tabindex="-1"><a class="header-anchor" href="#取消-ttl"><span>取消 TTL</span></a></h3><p>取消 TTL 的 SQL 语句如下所示：</p><div class="language-text line-numbers-mode" data-ext="text" data-title="text"><pre class="language-text"><code>IoTDB&gt; unset ttl to root.ln
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></div></div><p>取消设置 TTL 后，存储组<code>root.ln</code>中所有的数据都会被保存。</p><h3 id="显示-ttl" tabindex="-1"><a class="header-anchor" href="#显示-ttl"><span>显示 TTL</span></a></h3><p>显示 TTL 的 SQL 语句如下所示：</p><div class="language-text line-numbers-mode" data-ext="text" data-title="text"><pre class="language-text"><code>IoTDB&gt; SHOW ALL TTL
IoTDB&gt; SHOW TTL ON StorageGroupNames
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div></div></div><p>SHOW ALL TTL 这个例子会给出所有存储组的 TTL。<br> SHOW TTL ON root.group1,root.group2,root.group3 这个例子会显示指定的三个存储组的 TTL。<br> 注意：没有设置 TTL 的存储组的 TTL 将显示为 null。</p></div><!--[--><!----><!--]--><footer class="vp-page-meta"><div class="vp-meta-item edit-link"><a href="https://github.com/apache/iotdb-docs/edit/main/src/zh/UserGuide/V0.13.x/Operate-Metadata/TTL.md" rel="noopener noreferrer" target="_blank" aria-label="发现错误？在 GitHub 上编辑此页" class="nav-link vp-meta-label"><!--[--><svg xmlns="http://www.w3.org/2000/svg" class="icon edit-icon" viewBox="0 0 1024 1024" fill="currentColor" aria-label="edit icon"><path d="M430.818 653.65a60.46 60.46 0 0 1-50.96-93.281l71.69-114.012 7.773-10.365L816.038 80.138A60.46 60.46 0 0 1 859.225 62a60.46 60.46 0 0 1 43.186 18.138l43.186 43.186a60.46 60.46 0 0 1 0 86.373L588.879 565.55l-8.637 8.637-117.466 68.234a60.46 60.46 0 0 1-31.958 11.229z"></path><path d="M728.802 962H252.891A190.883 190.883 0 0 1 62.008 771.98V296.934a190.883 190.883 0 0 1 190.883-192.61h267.754a60.46 60.46 0 0 1 0 120.92H252.891a69.962 69.962 0 0 0-69.098 69.099V771.98a69.962 69.962 0 0 0 69.098 69.098h475.911A69.962 69.962 0 0 0 797.9 771.98V503.363a60.46 60.46 0 1 1 120.922 0V771.98A190.883 190.883 0 0 1 728.802 962z"></path></svg><!--]-->发现错误？在 GitHub 上编辑此页<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></div><div class="vp-meta-item git-info"><div class="update-time"><span class="vp-meta-label">上次编辑于: </span><!----></div><!----></div></footer><nav class="vp-page-nav"><a class="route-link nav-link prev" href="/zh/UserGuide/V0.13.x/Operate-Metadata/Template.html" aria-label="元数据模板"><div class="hint"><span class="arrow start"></span>上一页</div><div class="link"><!---->元数据模板</div></a><a class="route-link nav-link next" href="/zh/UserGuide/V0.13.x/Operate-Metadata/Auto-Create-MetaData.html" aria-label="自动创建元数据"><div class="hint">下一页<span class="arrow end"></span></div><div class="link">自动创建元数据<!----></div></a></nav><!----><!--[--><!----><!--]--><!--]--></main><!--]--><footer style="padding-bottom:2rem;"><span id="doc-version" style="display:none;">rel/0.13</span><p style="text-align:center;color:#909399;font-size:12px;margin:0 30px;">Copyright © 2024 The Apache Software Foundation.<br> Apache and the Apache feather logo are trademarks of The Apache Software Foundation</p><p style="text-align:center;margin-top:10px;color:#909399;font-size:12px;margin:0 30px;"><strong>Have a question?</strong> Connect with us on QQ, WeChat, or Slack. <a href="https://github.com/apache/iotdb/issues/1995">Join the community</a> now.</p></footer></div><!--]--><!--]--><!--[--><!----><!--]--><!--]--></div>
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