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clickable" type="button"><!----><span class="vp-sidebar-title">Query Data</span><span class="vp-arrow end"></span></button><!----></section></li><li><section class="vp-sidebar-group"><button class="vp-sidebar-header clickable" type="button"><!----><span class="vp-sidebar-title">Operators and Functions</span><span class="vp-arrow end"></span></button><!----></section></li><li><section class="vp-sidebar-group"><button class="vp-sidebar-header clickable active" type="button"><!----><span class="vp-sidebar-title">Trigger</span><span class="vp-arrow down"></span></button><ul class="vp-sidebar-links"><li><a class="route-link nav-link vp-sidebar-link vp-sidebar-page" href="/UserGuide/V1.0.x/Trigger/Instructions.html" aria-label="Instructions"><!---->Instructions<!----></a></li><li><a class="route-link nav-link vp-sidebar-link vp-sidebar-page" href="/UserGuide/V1.0.x/Trigger/Implement-Trigger.html" aria-label="How to implement a trigger"><!---->How to implement a trigger<!----></a></li><li><a class="route-link nav-link vp-sidebar-link vp-sidebar-page" href="/UserGuide/V1.0.x/Trigger/Trigger-Management.html" aria-label="Trigger Management"><!---->Trigger Management<!----></a></li><li><a class="route-link nav-link active vp-sidebar-link vp-sidebar-page active" href="/UserGuide/V1.0.x/Trigger/Notes.html" aria-label="Notes"><!---->Notes<!----></a></li><li><a class="route-link nav-link vp-sidebar-link vp-sidebar-page" href="/UserGuide/V1.0.x/Trigger/Configuration-Parameters.html" aria-label="Configuration-Parameters"><!---->Configuration-Parameters<!----></a></li></ul></section></li><li><section class="vp-sidebar-group"><button class="vp-sidebar-header clickable" type="button"><!----><span class="vp-sidebar-title">Monitor and Alert</span><span class="vp-arrow end"></span></button><!----></section></li><li><section class="vp-sidebar-group"><button class="vp-sidebar-header clickable" type="button"><!----><span class="vp-sidebar-title">Administration Management</span><span class="vp-arrow end"></span></button><!----></section></li><li><section class="vp-sidebar-group"><button class="vp-sidebar-header clickable" type="button"><!----><span class="vp-sidebar-title">Maintenance Tools</span><span class="vp-arrow end"></span></button><!----></section></li><li><section class="vp-sidebar-group"><button class="vp-sidebar-header clickable" type="button"><!----><span class="vp-sidebar-title">Collaboration of Edge and Cloud</span><span class="vp-arrow end"></span></button><!----></section></li><li><section class="vp-sidebar-group"><button class="vp-sidebar-header clickable" type="button"><!----><span class="vp-sidebar-title">Ecosystem Integration</span><span class="vp-arrow end"></span></button><!----></section></li><li><section class="vp-sidebar-group"><button class="vp-sidebar-header clickable" type="button"><!----><span class="vp-sidebar-title">Cluster</span><span class="vp-arrow end"></span></button><!----></section></li><li><section class="vp-sidebar-group"><button class="vp-sidebar-header clickable" type="button"><!----><span class="vp-sidebar-title">FAQ</span><span class="vp-arrow end"></span></button><!----></section></li><li><section class="vp-sidebar-group"><button class="vp-sidebar-header clickable" type="button"><!----><span class="vp-sidebar-title">Reference</span><span class="vp-arrow end"></span></button><!----></section></li></ul><!--[--><!----><!--]--></aside><!--[--><main id="main-content" class="vp-page"><!--[--><!--[--><!----><!--]--><!----><nav class="vp-breadcrumb disable"></nav><div class="vp-page-title"><h1><!---->Notes</h1><div class="page-info"><!----><!----><span class="page-date-info" aria-label="Writing Date"><svg xmlns="http://www.w3.org/2000/svg" class="icon calendar-icon" viewBox="0 0 1024 1024" fill="currentColor" aria-label="calendar icon"><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 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data-page-key="/UserGuide/V1.0.x/Trigger/Notes.html">...</span></span><span class="page-reading-time-info" aria-label="Reading Time"><svg xmlns="http://www.w3.org/2000/svg" class="icon timer-icon" viewBox="0 0 1024 1024" fill="currentColor" aria-label="timer icon"><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 1 min</span><meta property="timeRequired" content="PT1M"></span><!----><!----></div><hr></div><!----><!--[--><!----><!--]--><div class="theme-hope-content"><h1 id="notes" tabindex="-1"><a class="header-anchor" href="#notes"><span>Notes</span></a></h1><ul><li>The trigger takes effect from the time of registration, and does not process the existing historical data. **That is, only insertion requests that occur after the trigger is successfully registered will be listened to by the trigger. **</li><li>The fire process of trigger is synchronous currently, so you need to ensure the efficiency of the trigger, otherwise the writing performance may be greatly affected. <strong>You need to guarantee concurrency safety of triggers yourself</strong>.</li><li>Please do no register too many triggers in the cluster. Because the trigger information is fully stored in the ConfigNode, and there is a copy of the information in all DataNodes</li><li><strong>It is recommended to stop writing when registering triggers</strong>. Registering a trigger is not an atomic operation. When registering a trigger, there will be an intermediate state in which some nodes in the cluster have registered the trigger, and some nodes have not yet registered successfully. To avoid write requests on some nodes being listened to by triggers and not being listened to on some nodes, we recommend not to perform writes when registering triggers.</li><li>When the node holding the stateful trigger instance goes down, we will try to restore the corresponding instance on another node. During the recovery process, we will call the restore interface of the trigger class once.</li><li>The trigger JAR package has a size limit, which must be less than min(<code>config_node_ratis_log_appender_buffer_size_max</code>, 2G), where <code>config_node_ratis_log_appender_buffer_size_max</code> is a configuration item. For the specific meaning, please refer to the IOTDB configuration item description.</li><li><strong>It is better not to have classes with the same full class name but different function implementations in different JAR packages.</strong> For example, trigger1 and trigger2 correspond to resources trigger1.jar and trigger2.jar respectively. If two JAR packages contain a <code>org.apache.iotdb.trigger.example.AlertListener</code> class, when <code>CREATE TRIGGER</code> uses this class, the system will randomly load the class in one of the JAR packages, which will eventually leads the inconsistent behavior of trigger and other issues.</li></ul></div><!--[--><!----><!--]--><footer class="vp-page-meta"><div class="vp-meta-item edit-link"><a href="https://github.com/apache/iotdb-docs/edit/main/src/UserGuide/V1.0.x/Trigger/Notes.md" rel="noopener noreferrer" target="_blank" aria-label="Found Error? 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