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class="vp-sidebar" vp-sidebar><!--[--><p class="vp-sidebar-header iotdb-sidebar-header"><span class="vp-sidebar-title"></span></p><!----><!--]--><ul class="vp-sidebar-links"></ul><!----></aside><!--[--><main id="main-content" class="vp-page"><!--[--><!----><!----><nav class="vp-breadcrumb disable"></nav><div class="vp-page-title"><h1><!---->TTL Delete Data</h1><div class="page-info"><!----><!----><span class="page-date-info" aria-label="Writing Date📅" data-balloon-pos="up"><svg xmlns="http://www.w3.org/2000/svg" class="icon calendar-icon" viewBox="0 0 1024 1024" fill="currentColor" aria-label="calendar icon" name="calendar"><path d="M716.4 110.137c0-18.753-14.72-33.473-33.472-33.473-18.753 0-33.473 14.72-33.473 33.473v33.473h66.993v-33.473zm-334.87 0c0-18.753-14.72-33.473-33.473-33.473s-33.52 14.72-33.52 33.473v33.473h66.993v-33.473zm468.81 33.52H716.4v100.465c0 18.753-14.72 33.473-33.472 33.473a33.145 33.145 0 01-33.473-33.473V143.657H381.53v100.465c0 18.753-14.72 33.473-33.473 33.473a33.145 33.145 0 01-33.473-33.473V143.657H180.6A134.314 134.314 0 0046.66 277.595v535.756A134.314 134.314 0 00180.6 947.289h669.74a134.36 134.36 0 00133.94-133.938V277.595a134.314 134.314 0 00-133.94-133.938zm33.473 267.877H147.126a33.145 33.145 0 01-33.473-33.473c0-18.752 14.72-33.473 33.473-33.473h736.687c18.752 0 33.472 14.72 33.472 33.473a33.145 33.145 0 01-33.472 33.473z"></path></svg><span data-allow-mismatch="text">3/6/25</span><meta property="datePublished" content="2025-03-06T10:20:12.000Z"></span><!----><span class="page-reading-time-info" aria-label="Reading Time⌛" data-balloon-pos="up"><svg xmlns="http://www.w3.org/2000/svg" class="icon timer-icon" viewBox="0 0 1024 1024" fill="currentColor" aria-label="timer icon" name="timer"><path d="M799.387 122.15c4.402-2.978 7.38-7.897 7.38-13.463v-1.165c0-8.933-7.38-16.312-16.312-16.312H256.33c-8.933 0-16.311 7.38-16.311 16.312v1.165c0 5.825 2.977 10.874 7.637 13.592 4.143 194.44 97.22 354.963 220.201 392.763-122.204 37.542-214.893 196.511-220.2 389.397-4.661 5.049-7.638 11.651-7.638 19.03v5.825h566.49v-5.825c0-7.379-2.849-13.981-7.509-18.9-5.049-193.016-97.867-351.985-220.2-389.527 123.24-37.67 216.446-198.453 220.588-392.892zM531.16 450.445v352.632c117.674 1.553 211.787 40.778 211.787 88.676H304.097c0-48.286 95.149-87.382 213.728-88.676V450.445c-93.077-3.107-167.901-81.297-167.901-177.093 0-8.803 6.99-15.793 15.793-15.793 8.803 0 15.794 6.99 15.794 15.793 0 80.261 63.69 145.635 142.01 145.635s142.011-65.374 142.011-145.635c0-8.803 6.99-15.793 15.794-15.793s15.793 6.99 15.793 15.793c0 95.019-73.789 172.82-165.96 177.093z"></path></svg><span>About 3 min</span><meta property="timeRequired" content="PT3M"></span><!----><!----></div><hr></div><!----><div class="" vp-content><!----><div id="markdown-content"><h1 id="ttl-delete-data" tabindex="-1"><a class="header-anchor" href="#ttl-delete-data"><span>TTL Delete Data</span></a></h1><h2 id="overview" tabindex="-1"><a class="header-anchor" href="#overview"><span>Overview</span></a></h2><p>IoTDB supports setting data retention time (TTL) at the device level, allowing the system to automatically and periodically delete old data to effectively control disk space and maintain high query performance and low memory usage. TTL is set in milliseconds by default. Once data expires, it cannot be queried or written, but physical deletion is delayed until compaction. Please note that changes to TTL may temporarily affect data queryability, and if TTL is reduced or removed, previously invisible data due to TTL may reappear.</p><p>Important notes:</p><ul><li>TTL is set in milliseconds and is not affected by the time precision in the configuration file.</li><li>Changes to TTL may affect data queryability.</li><li>The system will eventually remove expired data, but there may be a delay.</li><li>TTL determines data expiration based on the data point timestamp, not the ingestion time.</li><li>The system supports setting up to 1000 TTL rules. When the limit is reached, existing rules must be removed before new ones can be added.</li><li>Supports device-level TTL starting from V1.3.3.</li></ul><h2 id="set-ttl" tabindex="-1"><a class="header-anchor" href="#set-ttl"><span>Set TTL</span></a></h2><h3 id="ttl-path-rule" tabindex="-1"><a class="header-anchor" href="#ttl-path-rule"><span>TTL Path Rule</span></a></h3><p>The path can only be prefix paths (i.e., the path cannot contain * , except ** in the last level).<br> This path will match devices and also allows users to specify paths without asterisks as specific databases or devices.<br> When the path does not contain asterisks, the system will check if it matches a database; if it matches a database, both the path and path.** will be set at the same time. Note: Device TTL settings do not verify the existence of metadata, i.e., it is allowed to set TTL for a non-existent device.</p><div class="language- line-numbers-mode" data-highlighter="shiki" data-ext="" style="background-color:#282c34;color:#abb2bf;"><pre class="shiki one-dark-pro vp-code"><code class="language-"><span class="line"><span>qualified paths：</span></span> |
| <span class="line"><span>root.**</span></span> |
| <span class="line"><span>root.db.**</span></span> |
| <span class="line"><span>root.db.group1.**</span></span> |
| <span class="line"><span>root.db</span></span> |
| <span class="line"><span>root.db.group1.d1</span></span> |
| <span class="line"><span></span></span> |
| <span class="line"><span>unqualified paths：</span></span> |
| <span class="line"><span>root.*.db</span></span> |
| <span class="line"><span>root.**.db.*</span></span> |
| <span class="line"><span>root.db.*</span></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><h3 id="ttl-applicable-rules" tabindex="-1"><a class="header-anchor" href="#ttl-applicable-rules"><span>TTL Applicable Rules</span></a></h3><p>When a device is subject to multiple TTL rules, the more precise and longer rules are prioritized. For example, for the device "root.bj.hd.dist001.turbine001", the rule "root.bj.hd.dist001.turbine001" takes precedence over "root.bj.hd.dist001.**", and the rule "root.bj.hd.dist001.**" takes precedence over "root.bj.hd.**".</p><h3 id="set-ttl-1" tabindex="-1"><a class="header-anchor" href="#set-ttl-1"><span>Set TTL</span></a></h3><p>The set ttl operation can be understood as setting a TTL rule, for example, setting ttl to root.sg.group1.** is equivalent to mounting ttl for all devices that can match this path pattern.<br> The unset ttl operation indicates unmounting TTL for the corresponding path pattern; if there is no corresponding TTL, nothing will be done.<br> If you want to set TTL to be infinitely large, you can use the INF keyword.<br> The SQL Statement for setting TTL is as follow:</p><div class="language- line-numbers-mode" data-highlighter="shiki" data-ext="" style="background-color:#282c34;color:#abb2bf;"><pre class="shiki one-dark-pro vp-code"><code class="language-"><span class="line"><span>set ttl to pathPattern 360000;</span></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div></div></div><p>Set the Time to Live (TTL) to a pathPattern of 360,000 milliseconds; the pathPattern should not contain a wildcard (*) in the middle and must end with a double asterisk (**). The pathPattern is used to match corresponding devices.<br> To maintain compatibility with older SQL syntax, if the user-provided pathPattern matches a database (db), the path pattern is automatically expanded to include all sub-paths denoted by path.**.<br> For instance, writing "set ttl to <a href="http://root.sg" target="_blank" rel="noopener noreferrer">root.sg</a> 360000" will automatically be transformed into "set ttl to <a href="http://root.sg" target="_blank" rel="noopener noreferrer">root.sg</a>.** 360000", which sets the TTL for all devices under <a href="http://root.sg" target="_blank" rel="noopener noreferrer">root.sg</a>. However, if the specified pathPattern does not match a database, the aforementioned logic will not apply. For example, writing "set ttl to root.sg.group 360000" will not be expanded to "root.sg.group.**" since root.sg.group does not match a database.<br> It is also permissible to specify a particular device without a wildcard (*).</p><h2 id="unset-ttl" tabindex="-1"><a class="header-anchor" href="#unset-ttl"><span>Unset TTL</span></a></h2><p>To unset TTL, we can use follwing SQL statement:</p><div class="language- line-numbers-mode" data-highlighter="shiki" data-ext="" style="background-color:#282c34;color:#abb2bf;"><pre class="shiki one-dark-pro vp-code"><code class="language-"><span class="line"><span>IoTDB> unset ttl from root.ln</span></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div></div></div><p>After unset TTL, all data will be accepted in <code>root.ln</code>.</p><div class="language- line-numbers-mode" data-highlighter="shiki" data-ext="" style="background-color:#282c34;color:#abb2bf;"><pre class="shiki one-dark-pro vp-code"><code class="language-"><span class="line"><span>IoTDB> unset ttl from root.sgcc.**</span></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div></div></div><p>Unset the TTL in the <code>root.sgcc</code> path.</p><p>New syntax</p><div class="language- line-numbers-mode" data-highlighter="shiki" data-ext="" style="background-color:#282c34;color:#abb2bf;"><pre class="shiki one-dark-pro vp-code"><code class="language-"><span class="line"><span>IoTDB> unset ttl from root.**</span></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div></div></div><p>Old syntax</p><div class="language- line-numbers-mode" data-highlighter="shiki" data-ext="" style="background-color:#282c34;color:#abb2bf;"><pre class="shiki one-dark-pro vp-code"><code class="language-"><span class="line"><span>IoTDB> unset ttl to root.**</span></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div></div></div><p>There is no functional difference between the old and new syntax, and they are compatible with each other.<br> The new syntax is just more conventional in terms of wording.</p><p>Unset the TTL setting for all path pattern.</p><h2 id="show-ttl" tabindex="-1"><a class="header-anchor" href="#show-ttl"><span>Show TTL</span></a></h2><p>To Show TTL, we can use following SQL statement:</p><p>show all ttl</p><div class="language- line-numbers-mode" data-highlighter="shiki" data-ext="" style="background-color:#282c34;color:#abb2bf;"><pre class="shiki one-dark-pro vp-code"><code class="language-"><span class="line"><span>IoTDB> SHOW ALL TTL</span></span> |
| <span class="line"><span>+--------------+--------+</span></span> |
| <span class="line"><span>| path| TTL|</span></span> |
| <span class="line"><span>| root.**|55555555|</span></span> |
| <span class="line"><span>| root.sg2.a.**|44440000|</span></span> |
| <span class="line"><span>+--------------+--------+</span></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><p>show ttl on pathPattern</p><div class="language- line-numbers-mode" data-highlighter="shiki" data-ext="" style="background-color:#282c34;color:#abb2bf;"><pre class="shiki one-dark-pro vp-code"><code class="language-"><span class="line"><span>IoTDB> SHOW TTL ON root.db.**;</span></span> |
| <span class="line"><span>+--------------+--------+</span></span> |
| <span class="line"><span>| path| TTL|</span></span> |
| <span class="line"><span>| root.db.**|55555555|</span></span> |
| <span class="line"><span>| root.db.a.**|44440000|</span></span> |
| <span class="line"><span>+--------------+--------+</span></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><p>The SHOW ALL TTL example gives the TTL for all path patterns.<br> The SHOW TTL ON pathPattern shows the TTL for the path pattern specified.</p><p>Display devices' ttl</p><div class="language- line-numbers-mode" data-highlighter="shiki" data-ext="" style="background-color:#282c34;color:#abb2bf;"><pre class="shiki one-dark-pro vp-code"><code class="language-"><span class="line"><span>IoTDB> show devices</span></span> |
| <span class="line"><span>+---------------+---------+---------+</span></span> |
| <span class="line"><span>| Device|IsAligned| TTL|</span></span> |
| <span class="line"><span>+---------------+---------+---------+</span></span> |
| <span class="line"><span>|root.sg.device1| false| 36000000|</span></span> |
| <span class="line"><span>|root.sg.device2| true| INF|</span></span> |
| <span class="line"><span>+---------------+---------+---------+</span></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><p>All devices will definitely have a TTL, meaning it cannot be null. INF represents infinity.</p></div><!----><!----><!----></div><footer class="vp-page-meta"><div class="vp-meta-item edit-link"><a class="auto-link external-link vp-meta-label" href="https://github.com/apache/iotdb-docs/edit/main/src/UserGuide/dev-1.3/Basic-Concept/TTL-Delete.md" aria-label="Found Error? Edit this page on GitHub" rel="noopener noreferrer" target="_blank"><!--[--><svg xmlns="http://www.w3.org/2000/svg" class="icon edit-icon" viewBox="0 0 1024 1024" fill="currentColor" aria-label="edit icon" name="edit"><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><!--]-->Found Error? Edit this page on GitHub<!----></a></div><div class="vp-meta-item git-info"><div class="update-time"><span class="vp-meta-label">Last Updated: </span><time class="vp-meta-info" datetime="2026-04-10T04:10:06.000Z" data-allow-mismatch>4/10/26, 4:10 AM</time></div><!----></div></footer><!----><!----><!----><!--]--></main><!--]--><footer class="site-footer"><span id="doc-version" style="display:none;">dev-1.3</span><p class="copyright-text">Copyright © 2026 The Apache Software Foundation. |
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