| <!doctype html> |
| <html lang="zh-CN" data-theme="light"> |
| <head> |
| <meta charset="utf-8" /> |
| <meta name="viewport" content="width=device-width,initial-scale=1" /> |
| <meta name="generator" content="VuePress 2.0.0-rc.9" /> |
| <meta name="theme" content="VuePress Theme Hope 2.0.0-rc.34" /> |
| <style> |
| html { |
| background: var(--bg-color, #fff); |
| } |
| |
| html[data-theme="dark"] { |
| background: var(--bg-color, #1d1e1f); |
| } |
| |
| body { |
| background: var(--bg-color); |
| } |
| </style> |
| <script> |
| const userMode = localStorage.getItem("vuepress-theme-hope-scheme"); |
| const systemDarkMode = |
| window.matchMedia && |
| window.matchMedia("(prefers-color-scheme: dark)").matches; |
| |
| if (userMode === "dark" || (userMode !== "light" && systemDarkMode)) { |
| document.documentElement.setAttribute("data-theme", "dark"); |
| } |
| </script> |
| <link rel="alternate" hreflang="en-us" href="https://iotdb.apache.org/UserGuide/V1.1.x/Operators-Functions/Sample.html"><meta property="og:url" content="https://iotdb.apache.org/zh/UserGuide/V1.1.x/Operators-Functions/Sample.html"><meta property="og:site_name" content="IoTDB Website"><meta property="og:description" content="采样函数 等数量分桶降采样函数 本函数对输入序列进行等数量分桶采样，即根据用户给定的降采样比例和降采样方法将输入序列按固定点数等分为若干桶。在每个桶内通过给定的采样方法进行采样。 等数量分桶随机采样 函数简介 对等数量分桶后，桶内进行随机采样。 使用示例 输入序列:root.ln.wf01.wt01.temperature从0.0-99.0共100条数..."><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"> |
| var _paq = window._paq = window._paq || []; |
| /* tracker methods like "setCustomDimension" should be called before "trackPageView" */ |
| _paq.push(["setDoNotTrack", true]); |
| _paq.push(["disableCookies"]); |
| _paq.push(['trackPageView']); |
| _paq.push(['enableLinkTracking']); |
| (function() { |
| var u="https://analytics.apache.org/"; |
| _paq.push(['setTrackerUrl', u+'matomo.php']); |
| _paq.push(['setSiteId', '56']); |
| var d=document, g=d.createElement('script'), s=d.getElementsByTagName('script')[0]; |
| g.async=true; g.src=u+'matomo.js'; s.parentNode.insertBefore(g,s); |
| })(); |
| </script><title>IoTDB Website</title><meta name="description" content="采样函数 等数量分桶降采样函数 本函数对输入序列进行等数量分桶采样，即根据用户给定的降采样比例和降采样方法将输入序列按固定点数等分为若干桶。在每个桶内通过给定的采样方法进行采样。 等数量分桶随机采样 函数简介 对等数量分桶后，桶内进行随机采样。 使用示例 输入序列:root.ln.wf01.wt01.temperature从0.0-99.0共100条数..."> |
| <link rel="preload" href="/assets/style-DnEHAOmf.css" as="style"><link rel="stylesheet" href="/assets/style-DnEHAOmf.css"> |
| <link rel="modulepreload" href="/assets/app-DrPcRZG6.js"><link rel="modulepreload" href="/assets/Sample.html-tMBYOuRE.js"> |
| |
| </head> |
| <body> |
| <div id="app"><!--[--><!--[--><!--[--><span tabindex="-1"></span><a href="#main-content" class="vp-skip-link sr-only">跳至主要內容</a><!--]--><!--[--><div class="theme-container has-toc"><!--[--><header id="navbar" class="vp-navbar hide-icon"><div class="vp-navbar-start"><button type="button" class="vp-toggle-sidebar-button" title="Toggle Sidebar"><span class="icon"></span></button><!--[--><!----><!--]--><!--[--><a class="route-link vp-brand" href="/zh/"><img class="vp-nav-logo" src="/logo.png" alt><!----><span class="vp-site-name hide-in-pad">IoTDB Website</span></a><!--]--><!--[--><!----><!--]--></div><div class="vp-navbar-center"><!--[--><!----><!--]--><!--[--><!--]--><!--[--><!----><!--]--></div><div class="vp-navbar-end"><!--[--><!----><!--]--><!--[--><!--[--><div id="docsearch-container" style="display:none;"></div><div><button type="button" class="DocSearch DocSearch-Button" aria-label="搜索文档"><span class="DocSearch-Button-Container"><svg width="20" height="20" class="DocSearch-Search-Icon" viewBox="0 0 20 20"><path d="M14.386 14.386l4.0877 4.0877-4.0877-4.0877c-2.9418 2.9419-7.7115 2.9419-10.6533 0-2.9419-2.9418-2.9419-7.7115 0-10.6533 2.9418-2.9419 7.7115-2.9419 10.6533 0 2.9419 2.9418 2.9419 7.7115 0 10.6533z" stroke="currentColor" fill="none" fill-rule="evenodd" stroke-linecap="round" stroke-linejoin="round"></path></svg><span class="DocSearch-Button-Placeholder">搜索文档</span></span><span class="DocSearch-Button-Keys"><kbd class="DocSearch-Button-Key"><svg width="15" height="15" class="DocSearch-Control-Key-Icon"><path d="M4.505 4.496h2M5.505 5.496v5M8.216 4.496l.055 5.993M10 7.5c.333.333.5.667.5 1v2M12.326 4.5v5.996M8.384 4.496c1.674 0 2.116 0 2.116 1.5s-.442 1.5-2.116 1.5M3.205 9.303c-.09.448-.277 1.21-1.241 1.203C1 10.5.5 9.513.5 8V7c0-1.57.5-2.5 1.464-2.494.964.006 1.134.598 1.24 1.342M12.553 10.5h1.953" stroke-width="1.2" stroke="currentColor" fill="none" stroke-linecap="square"></path></svg></kbd><kbd class="DocSearch-Button-Key">K</kbd></span></button></div><!--]--><nav class="vp-nav-links"><div class="vp-nav-item hide-in-mobile"><div class="dropdown-wrapper"><button type="button" class="dropdown-title" aria-label="文档"><span class="title"><!---->文档</span><span class="arrow"></span><ul class="nav-dropdown"><li class="dropdown-item"><a class="route-link nav-link" href="/zh/UserGuide/latest/QuickStart/QuickStart.html" aria-label="v1.3.x"><!---->v1.3.x<!----></a></li><li class="dropdown-item"><a class="route-link nav-link" href="/zh/UserGuide/V1.2.x/QuickStart/QuickStart.html" aria-label="v1.2.x"><!---->v1.2.x<!----></a></li><li class="dropdown-item"><a class="route-link nav-link" href="/zh/UserGuide/V1.1.x/QuickStart/QuickStart.html" aria-label="v1.1.x"><!---->v1.1.x<!----></a></li><li class="dropdown-item"><a class="route-link nav-link" href="/zh/UserGuide/V1.0.x/QuickStart/QuickStart.html" aria-label="v1.0.x"><!---->v1.0.x<!----></a></li><li class="dropdown-item"><a class="route-link nav-link" href="/zh/UserGuide/V0.13.x/QuickStart/QuickStart.html" aria-label="v0.13.x"><!---->v0.13.x<!----></a></li></ul></button></div></div><div class="vp-nav-item hide-in-mobile"><a href="https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=177051872" rel="noopener noreferrer" target="_blank" aria-label="系统设计" class="nav-link"><!---->系统设计<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-nav-item hide-in-mobile"><a class="route-link nav-link" href="/zh/Download/" aria-label="下载"><!---->下载<!----></a></div><div class="vp-nav-item hide-in-mobile"><div class="dropdown-wrapper"><button type="button" class="dropdown-title" aria-label="社区"><span class="title"><!---->社区</span><span class="arrow"></span><ul class="nav-dropdown"><li class="dropdown-item"><a class="route-link nav-link" href="/zh/Community/About.html" aria-label="关于社区"><!---->关于社区<!----></a></li><li class="dropdown-item"><a class="route-link nav-link" href="/zh/Community/Development-Guide.html" aria-label="贡献指南"><!---->贡献指南<!----></a></li><li class="dropdown-item"><a class="route-link nav-link" href="/zh/Community/Powered-By.html" aria-label="社区伙伴"><!---->社区伙伴<!----></a></li><li class="dropdown-item"><a class="route-link nav-link" href="/zh/Community/Feedback.html" aria-label="交流与反馈"><!---->交流与反馈<!----></a></li><li class="dropdown-item"><a class="route-link nav-link" href="/zh/Community/Materials.html" aria-label="活动与报告"><!---->活动与报告<!----></a></li><li class="dropdown-item"><a class="route-link nav-link" href="/zh/Community/Community-Project-Committers.html" aria-label="Commiters"><!---->Commiters<!----></a></li></ul></button></div></div><div class="vp-nav-item hide-in-mobile"><div class="dropdown-wrapper"><button type="button" class="dropdown-title" aria-label="ASF"><span class="title"><!---->ASF</span><span class="arrow"></span><ul class="nav-dropdown"><li class="dropdown-item"><a href="https://www.apache.org/" rel="noopener noreferrer" target="_blank" aria-label="基金会" class="nav-link"><!---->基金会<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></li><li class="dropdown-item"><a href="https://www.apache.org/licenses/" rel="noopener noreferrer" target="_blank" aria-label="许可证" class="nav-link"><!---->许可证<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></li><li class="dropdown-item"><a href="https://www.apache.org/security/" rel="noopener noreferrer" target="_blank" aria-label="安全" class="nav-link"><!---->安全<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></li><li class="dropdown-item"><a href="https://www.apache.org/foundation/sponsorship.html" rel="noopener noreferrer" target="_blank" aria-label="赞助" class="nav-link"><!---->赞助<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></li><li class="dropdown-item"><a href="https://www.apache.org/foundation/thanks.html" rel="noopener noreferrer" target="_blank" aria-label="致谢" class="nav-link"><!---->致谢<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></li><li class="dropdown-item"><a href="https://www.apache.org/events/current-event" rel="noopener noreferrer" target="_blank" aria-label="活动" class="nav-link"><!---->活动<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></li><li class="dropdown-item"><a href="https://privacy.apache.org/policies/privacy-policy-public.html" rel="noopener noreferrer" target="_blank" aria-label="隐私" class="nav-link"><!---->隐私<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></li></ul></button></div></div></nav><div class="vp-nav-item"><div class="dropdown-wrapper"><button type="button" class="dropdown-title" aria-label="选择语言"><!--[--><svg xmlns="http://www.w3.org/2000/svg" class="icon i18n-icon" viewBox="0 0 1024 1024" fill="currentColor" aria-label="i18n icon" style="width:1rem;height:1rem;vertical-align:middle;"><path d="M379.392 460.8 494.08 575.488l-42.496 102.4L307.2 532.48 138.24 701.44l-71.68-72.704L234.496 460.8l-45.056-45.056c-27.136-27.136-51.2-66.56-66.56-108.544h112.64c7.68 14.336 16.896 27.136 26.112 35.84l45.568 46.08 45.056-45.056C382.976 312.32 409.6 247.808 409.6 204.8H0V102.4h256V0h102.4v102.4h256v102.4H512c0 70.144-37.888 161.28-87.04 210.944L378.88 460.8zM576 870.4 512 1024H409.6l256-614.4H768l256 614.4H921.6l-64-153.6H576zM618.496 768h196.608L716.8 532.48 618.496 768z"></path></svg><!--]--><span class="arrow"></span><ul class="nav-dropdown"><li class="dropdown-item"><a class="route-link nav-link" href="/UserGuide/V1.1.x/Operators-Functions/Sample.html" aria-label="English"><!---->English<!----></a></li><li class="dropdown-item"><a class="route-link nav-link active" href="/zh/UserGuide/V1.1.x/Operators-Functions/Sample.html" aria-label="简体中文"><!---->简体中文<!----></a></li></ul></button></div></div><div class="vp-nav-item hide-in-mobile"><button type="button" id="appearance-switch"><svg xmlns="http://www.w3.org/2000/svg" class="icon auto-icon" viewBox="0 0 1024 1024" fill="currentColor" aria-label="auto icon" style="display:none;"><path d="M512 992C246.92 992 32 777.08 32 512S246.92 32 512 32s480 214.92 480 480-214.92 480-480 480zm0-840c-198.78 0-360 161.22-360 360 0 198.84 161.22 360 360 360s360-161.16 360-360c0-198.78-161.22-360-360-360zm0 660V212c165.72 0 300 134.34 300 300 0 165.72-134.28 300-300 300z"></path></svg><svg xmlns="http://www.w3.org/2000/svg" class="icon dark-icon" viewBox="0 0 1024 1024" fill="currentColor" aria-label="dark icon" style="display:none;"><path d="M524.8 938.667h-4.267a439.893 439.893 0 0 1-313.173-134.4 446.293 446.293 0 0 1-11.093-597.334A432.213 432.213 0 0 1 366.933 90.027a42.667 42.667 0 0 1 45.227 9.386 42.667 42.667 0 0 1 10.24 42.667 358.4 358.4 0 0 0 82.773 375.893 361.387 361.387 0 0 0 376.747 82.774 42.667 42.667 0 0 1 54.187 55.04 433.493 433.493 0 0 1-99.84 154.88 438.613 438.613 0 0 1-311.467 128z"></path></svg><svg xmlns="http://www.w3.org/2000/svg" class="icon light-icon" viewBox="0 0 1024 1024" fill="currentColor" aria-label="light icon" style="display:block;"><path d="M952 552h-80a40 40 0 0 1 0-80h80a40 40 0 0 1 0 80zM801.88 280.08a41 41 0 0 1-57.96-57.96l57.96-58a41.04 41.04 0 0 1 58 58l-58 57.96zM512 752a240 240 0 1 1 0-480 240 240 0 0 1 0 480zm0-560a40 40 0 0 1-40-40V72a40 40 0 0 1 80 0v80a40 40 0 0 1-40 40zm-289.88 88.08-58-57.96a41.04 41.04 0 0 1 58-58l57.96 58a41 41 0 0 1-57.96 57.96zM192 512a40 40 0 0 1-40 40H72a40 40 0 0 1 0-80h80a40 40 0 0 1 40 40zm30.12 231.92a41 41 0 0 1 57.96 57.96l-57.96 58a41.04 41.04 0 0 1-58-58l58-57.96zM512 832a40 40 0 0 1 40 40v80a40 40 0 0 1-80 0v-80a40 40 0 0 1 40-40zm289.88-88.08 58 57.96a41.04 41.04 0 0 1-58 58l-57.96-58a41 41 0 0 1 57.96-57.96z"></path></svg></button></div><div class="vp-nav-item vp-action"><a class="vp-action-link" href="https://github.com/apache/iotdb" target="_blank" rel="noopener noreferrer" aria-label="GitHub"><svg xmlns="http://www.w3.org/2000/svg" class="icon github-icon" viewBox="0 0 1024 1024" fill="currentColor" aria-label="github icon" style="width:1.25rem;height:1.25rem;vertical-align:middle;"><path d="M511.957 21.333C241.024 21.333 21.333 240.981 21.333 512c0 216.832 140.544 400.725 335.574 465.664 24.49 4.395 32.256-10.07 32.256-23.083 0-11.69.256-44.245 0-85.205-136.448 29.61-164.736-64.64-164.736-64.64-22.315-56.704-54.4-71.765-54.4-71.765-44.587-30.464 3.285-29.824 3.285-29.824 49.195 3.413 75.179 50.517 75.179 50.517 43.776 75.008 114.816 53.333 142.762 40.79 4.523-31.66 17.152-53.377 31.19-65.537-108.971-12.458-223.488-54.485-223.488-242.602 0-53.547 19.114-97.323 50.517-131.67-5.035-12.33-21.93-62.293 4.779-129.834 0 0 41.258-13.184 134.912 50.346a469.803 469.803 0 0 1 122.88-16.554c41.642.213 83.626 5.632 122.88 16.554 93.653-63.488 134.784-50.346 134.784-50.346 26.752 67.541 9.898 117.504 4.864 129.834 31.402 34.347 50.474 78.123 50.474 131.67 0 188.586-114.73 230.016-224.042 242.09 17.578 15.232 33.578 44.672 33.578 90.454v135.85c0 13.142 7.936 27.606 32.854 22.87C862.25 912.597 1002.667 728.747 1002.667 512c0-271.019-219.648-490.667-490.71-490.667z"></path></svg></a></div><!--]--><!--[--><!----><!--]--><button type="button" class="vp-toggle-navbar-button" aria-label="Toggle Navbar" aria-expanded="false" aria-controls="nav-screen"><span><span class="vp-top"></span><span class="vp-middle"></span><span class="vp-bottom"></span></span></button></div></header><!----><!--]--><!----><div class="toggle-sidebar-wrapper"><span class="arrow start"></span></div><aside id="sidebar" class="vp-sidebar"><!--[--><!----><!--]--><ul class="vp-sidebar-links"><li><section class="vp-sidebar-group"><p class="vp-sidebar-header"><!----><span class="vp-sidebar-title">IoTDB用户手册 (V1.1.x)</span><!----></p><ul class="vp-sidebar-links"></ul></section></li><li><section class="vp-sidebar-group"><button class="vp-sidebar-header clickable" type="button"><!----><span class="vp-sidebar-title">关于IoTDB</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">快速上手</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">数据模式与概念</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">语法约定</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">应用编程接口</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">元数据操作</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">数据写入（数据更新）</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">数据删除</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">数据查询</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">运算符和函数</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="/zh/UserGuide/V1.1.x/Operators-Functions/Overview.html" aria-label="概述"><!---->概述<!----></a></li><li><a class="route-link nav-link vp-sidebar-link vp-sidebar-page" href="/zh/UserGuide/V1.1.x/Operators-Functions/User-Defined-Function.html" aria-label="用户自定义函数"><!---->用户自定义函数<!----></a></li><li><a class="route-link nav-link vp-sidebar-link vp-sidebar-page" href="/zh/UserGuide/V1.1.x/Operators-Functions/Aggregation.html" aria-label="聚合函数"><!---->聚合函数<!----></a></li><li><a class="route-link nav-link vp-sidebar-link vp-sidebar-page" href="/zh/UserGuide/V1.1.x/Operators-Functions/Mathematical.html" aria-label="算数运算符和函数"><!---->算数运算符和函数<!----></a></li><li><a class="route-link nav-link vp-sidebar-link vp-sidebar-page" href="/zh/UserGuide/V1.1.x/Operators-Functions/Comparison.html" aria-label="比较运算符和函数"><!---->比较运算符和函数<!----></a></li><li><a class="route-link nav-link vp-sidebar-link vp-sidebar-page" href="/zh/UserGuide/V1.1.x/Operators-Functions/Logical.html" aria-label="逻辑运算符"><!---->逻辑运算符<!----></a></li><li><a class="route-link nav-link vp-sidebar-link vp-sidebar-page" href="/zh/UserGuide/V1.1.x/Operators-Functions/String.html" aria-label="字符串处理"><!---->字符串处理<!----></a></li><li><a class="route-link nav-link vp-sidebar-link vp-sidebar-page" href="/zh/UserGuide/V1.1.x/Operators-Functions/Conversion.html" aria-label="数据类型转换"><!---->数据类型转换<!----></a></li><li><a class="route-link nav-link vp-sidebar-link vp-sidebar-page" href="/zh/UserGuide/V1.1.x/Operators-Functions/Constant.html" aria-label="常序列生成"><!---->常序列生成<!----></a></li><li><a class="route-link nav-link vp-sidebar-link vp-sidebar-page" href="/zh/UserGuide/V1.1.x/Operators-Functions/Selection.html" aria-label="选择函数"><!---->选择函数<!----></a></li><li><a class="route-link nav-link vp-sidebar-link vp-sidebar-page" href="/zh/UserGuide/V1.1.x/Operators-Functions/Continuous-Interval.html" aria-label="区间查询"><!---->区间查询<!----></a></li><li><a class="route-link nav-link vp-sidebar-link vp-sidebar-page" href="/zh/UserGuide/V1.1.x/Operators-Functions/Variation-Trend.html" aria-label="趋势计算"><!---->趋势计算<!----></a></li><li><a class="route-link nav-link active vp-sidebar-link vp-sidebar-page active" href="/zh/UserGuide/V1.1.x/Operators-Functions/Sample.html" aria-label="采样函数"><!---->采样函数<!----></a></li><li><a class="route-link nav-link vp-sidebar-link vp-sidebar-page" href="/zh/UserGuide/V1.1.x/Operators-Functions/Time-Series.html" aria-label="时间序列处理"><!---->时间序列处理<!----></a></li><li><a class="route-link nav-link vp-sidebar-link vp-sidebar-page" href="/zh/UserGuide/V1.1.x/Operators-Functions/Lambda.html" aria-label="Lambda 表达式"><!---->Lambda 表达式<!----></a></li><li><a class="route-link nav-link vp-sidebar-link vp-sidebar-page" href="/zh/UserGuide/V1.1.x/Operators-Functions/Data-Profiling.html" aria-label="数据画像"><!---->数据画像<!----></a></li><li><a class="route-link nav-link vp-sidebar-link vp-sidebar-page" href="/zh/UserGuide/V1.1.x/Operators-Functions/Anomaly-Detection.html" aria-label="异常检测"><!---->异常检测<!----></a></li><li><a class="route-link nav-link vp-sidebar-link vp-sidebar-page" href="/zh/UserGuide/V1.1.x/Operators-Functions/Data-Matching.html" aria-label="数据匹配"><!---->数据匹配<!----></a></li><li><a class="route-link nav-link vp-sidebar-link vp-sidebar-page" href="/zh/UserGuide/V1.1.x/Operators-Functions/Frequency-Domain.html" aria-label="频域分析"><!---->频域分析<!----></a></li><li><a class="route-link nav-link vp-sidebar-link vp-sidebar-page" href="/zh/UserGuide/V1.1.x/Operators-Functions/Data-Quality.html" aria-label="数据质量"><!---->数据质量<!----></a></li><li><a class="route-link nav-link vp-sidebar-link vp-sidebar-page" href="/zh/UserGuide/V1.1.x/Operators-Functions/Data-Repairing.html" aria-label="数据修复"><!---->数据修复<!----></a></li><li><a class="route-link nav-link vp-sidebar-link vp-sidebar-page" href="/zh/UserGuide/V1.1.x/Operators-Functions/Series-Discovery.html" aria-label="序列发现"><!---->序列发现<!----></a></li><li><a class="route-link nav-link vp-sidebar-link vp-sidebar-page" href="/zh/UserGuide/V1.1.x/Operators-Functions/Machine-Learning.html" aria-label="机器学习"><!---->机器学习<!----></a></li></ul></section></li><li><section class="vp-sidebar-group"><button class="vp-sidebar-header clickable" type="button"><!----><span class="vp-sidebar-title">触发器</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">监控告警</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">权限管理</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">运维工具</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">端云协同</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">系统集成</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">分布式</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">参考</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><!----></h1><div class="page-info"><!----><!----><span class="page-date-info" aria-label="写作日期"><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 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><!----></span><meta property="datePublished" content="2023-07-10T03:11:17.000Z"></span><span class="page-pageview-info" aria-label="访问量"><svg xmlns="http://www.w3.org/2000/svg" class="icon eye-icon" viewBox="0 0 1024 1024" fill="currentColor" aria-label="eye icon"><path d="M992 512.096c0-5.76-.992-10.592-1.28-11.136-.192-2.88-1.152-8.064-2.08-10.816-.256-.672-.544-1.376-.832-2.08-.48-1.568-1.024-3.104-1.6-4.32C897.664 290.112 707.104 160 512 160c-195.072 0-385.632 130.016-473.76 322.592-1.056 2.112-1.792 4.096-2.272 5.856a55.512 55.512 0 00-.64 1.6c-1.76 5.088-1.792 8.64-1.632 7.744-.832 3.744-1.568 11.168-1.568 11.168-.224 2.272-.224 4.032.032 6.304 0 0 .736 6.464 1.088 7.808.128 1.824.576 4.512 1.12 6.976h-.032c.448 2.08 1.12 4.096 1.984 6.08.48 1.536.992 2.976 1.472 4.032C126.432 733.856 316.992 864 512 864c195.136 0 385.696-130.048 473.216-321.696 1.376-2.496 2.24-4.832 2.848-6.912.256-.608.48-1.184.672-1.728 1.536-4.48 1.856-8.32 1.728-8.32l-.032.032c.608-3.104 1.568-7.744 1.568-13.28zM512 672c-88.224 0-160-71.776-160-160s71.776-160 160-160 160 71.776 160 160-71.776 160-160 160z"></path></svg><span id="ArtalkPV" class="vp-pageview waline-pageview-count" data-path="/zh/UserGuide/V1.1.x/Operators-Functions/Sample.html" data-page-key="/zh/UserGuide/V1.1.x/Operators-Functions/Sample.html">...</span></span><span class="page-reading-time-info" aria-label="阅读时间"><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>大约 14 分钟</span><meta property="timeRequired" content="PT14M"></span><!----><!----></div><hr></div><div class="vp-toc-placeholder"><aside id="toc"><!--[--><!----><!--]--><div class="vp-toc-header">此页内容<button type="button" class="print-button" title="打印"><svg xmlns="http://www.w3.org/2000/svg" class="icon print-icon" viewBox="0 0 1024 1024" fill="currentColor" aria-label="print icon"><path d="M819.2 364.8h-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="#采样函数">采样函数</a></li><li><ul class="vp-toc-list"><!--[--><li class="vp-toc-item"><a class="route-link vp-toc-link level3" href="#等数量分桶降采样函数">等数量分桶降采样函数</a></li><!----><!--]--><!--[--><li class="vp-toc-item"><a class="route-link vp-toc-link level3" href="#m4函数">M4函数</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="采样函数" tabindex="-1"><a class="header-anchor" href="#采样函数"><span>采样函数</span></a></h2><h3 id="等数量分桶降采样函数" tabindex="-1"><a class="header-anchor" href="#等数量分桶降采样函数"><span>等数量分桶降采样函数</span></a></h3><p>本函数对输入序列进行等数量分桶采样，即根据用户给定的降采样比例和降采样方法将输入序列按固定点数等分为若干桶。在每个桶内通过给定的采样方法进行采样。</p><h4 id="等数量分桶随机采样" tabindex="-1"><a class="header-anchor" href="#等数量分桶随机采样"><span>等数量分桶随机采样</span></a></h4><h5 id="函数简介" tabindex="-1"><a class="header-anchor" href="#函数简介"><span>函数简介</span></a></h5><p>对等数量分桶后，桶内进行随机采样。</p><table><thead><tr><th>函数名</th><th>可接收的输入序列类型</th><th>必要的属性参数</th><th>输出序列类型</th><th>功能类型</th></tr></thead><tbody><tr><td>EQUAL_SIZE_BUCKET_RANDOM_SAMPLE</td><td>INT32 / INT64 / FLOAT / DOUBLE</td><td>降采样比例 <code>proportion</code>，取值范围为<code>(0, 1]</code>，默认为<code>0.1</code></td><td>INT32 / INT64 / FLOAT / DOUBLE</td><td>返回符合采样比例的等分桶随机采样</td></tr></tbody></table><h5 id="使用示例" tabindex="-1"><a class="header-anchor" href="#使用示例"><span>使用示例</span></a></h5><p>输入序列:<code>root.ln.wf01.wt01.temperature</code>从<code>0.0-99.0</code>共<code>100</code>条数据。</p><div class="language-text line-numbers-mode" data-ext="text" data-title="text"><pre class="language-text"><code>IoTDB> select temperature from root.ln.wf01.wt01; |
| +-----------------------------+-----------------------------+ |
| | Time|root.ln.wf01.wt01.temperature| |
| +-----------------------------+-----------------------------+ |
| |1970-01-01T08:00:00.000+08:00| 0.0| |
| |1970-01-01T08:00:00.001+08:00| 1.0| |
| |1970-01-01T08:00:00.002+08:00| 2.0| |
| |1970-01-01T08:00:00.003+08:00| 3.0| |
| |1970-01-01T08:00:00.004+08:00| 4.0| |
| |1970-01-01T08:00:00.005+08:00| 5.0| |
| |1970-01-01T08:00:00.006+08:00| 6.0| |
| |1970-01-01T08:00:00.007+08:00| 7.0| |
| |1970-01-01T08:00:00.008+08:00| 8.0| |
| |1970-01-01T08:00:00.009+08:00| 9.0| |
| |1970-01-01T08:00:00.010+08:00| 10.0| |
| |1970-01-01T08:00:00.011+08:00| 11.0| |
| |1970-01-01T08:00:00.012+08:00| 12.0| |
| |.............................|.............................| |
| |1970-01-01T08:00:00.089+08:00| 89.0| |
| |1970-01-01T08:00:00.090+08:00| 90.0| |
| |1970-01-01T08:00:00.091+08:00| 91.0| |
| |1970-01-01T08:00:00.092+08:00| 92.0| |
| |1970-01-01T08:00:00.093+08:00| 93.0| |
| |1970-01-01T08:00:00.094+08:00| 94.0| |
| |1970-01-01T08:00:00.095+08:00| 95.0| |
| |1970-01-01T08:00:00.096+08:00| 96.0| |
| |1970-01-01T08:00:00.097+08:00| 97.0| |
| |1970-01-01T08:00:00.098+08:00| 98.0| |
| |1970-01-01T08:00:00.099+08:00| 99.0| |
| +-----------------------------+-----------------------------+ |
| </code></pre><div class="line-numbers" aria-hidden="true"><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 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 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><p>sql:</p><div class="language-sql line-numbers-mode" data-ext="sql" data-title="sql"><pre class="language-sql"><code><span class="token keyword">select</span> equal_size_bucket_random_sample<span class="token punctuation">(</span>temperature<span class="token punctuation">,</span><span class="token string">'proportion'</span><span class="token operator">=</span><span class="token string">'0.1'</span><span class="token punctuation">)</span> <span class="token keyword">as</span> random_sample <span class="token keyword">from</span> root<span class="token punctuation">.</span>ln<span class="token punctuation">.</span>wf01<span class="token punctuation">.</span>wt01<span class="token punctuation">;</span> |
| </code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></div></div><p>结果:</p><div class="language-text line-numbers-mode" data-ext="text" data-title="text"><pre class="language-text"><code>+-----------------------------+-------------+ |
| | Time|random_sample| |
| +-----------------------------+-------------+ |
| |1970-01-01T08:00:00.007+08:00| 7.0| |
| |1970-01-01T08:00:00.014+08:00| 14.0| |
| |1970-01-01T08:00:00.020+08:00| 20.0| |
| |1970-01-01T08:00:00.035+08:00| 35.0| |
| |1970-01-01T08:00:00.047+08:00| 47.0| |
| |1970-01-01T08:00:00.059+08:00| 59.0| |
| |1970-01-01T08:00:00.063+08:00| 63.0| |
| |1970-01-01T08:00:00.079+08:00| 79.0| |
| |1970-01-01T08:00:00.086+08:00| 86.0| |
| |1970-01-01T08:00:00.096+08:00| 96.0| |
| +-----------------------------+-------------+ |
| Total line number = 10 |
| It costs 0.024s |
| </code></pre><div class="line-numbers" aria-hidden="true"><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 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><h4 id="等数量分桶聚合采样" tabindex="-1"><a class="header-anchor" href="#等数量分桶聚合采样"><span>等数量分桶聚合采样</span></a></h4><h5 id="函数简介-1" tabindex="-1"><a class="header-anchor" href="#函数简介-1"><span>函数简介</span></a></h5><p>采用聚合采样法对输入序列进行采样，用户需要另外提供一个聚合函数参数即</p><ul><li><code>type</code>：聚合类型，取值为<code>avg</code>或<code>max</code>或<code>min</code>或<code>sum</code>或<code>extreme</code>或<code>variance</code>。在缺省情况下，采用<code>avg</code>。其中<code>extreme</code>表示等分桶中，绝对值最大的值。<code>variance</code>表示采样等分桶中的方差。</li></ul><p>每个桶采样输出的时间戳为这个桶第一个点的时间戳</p><table><thead><tr><th>函数名</th><th>可接收的输入序列类型</th><th>必要的属性参数</th><th>输出序列类型</th><th>功能类型</th></tr></thead><tbody><tr><td>EQUAL_SIZE_BUCKET_AGG_SAMPLE</td><td>INT32 / INT64 / FLOAT / DOUBLE</td><td><code>proportion</code>取值范围为<code>(0, 1]</code>，默认为<code>0.1</code><br><code>type</code>:取值类型有<code>avg</code>, <code>max</code>, <code>min</code>, <code>sum</code>, <code>extreme</code>, <code>variance</code>, 默认为<code>avg</code></td><td>INT32 / INT64 / FLOAT / DOUBLE</td><td>返回符合采样比例的等分桶聚合采样</td></tr></tbody></table><h5 id="使用示例-1" tabindex="-1"><a class="header-anchor" href="#使用示例-1"><span>使用示例</span></a></h5><p>输入序列:<code>root.ln.wf01.wt01.temperature</code>从<code>0.0-99.0</code>共<code>100</code>条有序数据，同等分桶随机采样的测试数据。</p><p>sql:</p><div class="language-sql line-numbers-mode" data-ext="sql" data-title="sql"><pre class="language-sql"><code><span class="token keyword">select</span> equal_size_bucket_agg_sample<span class="token punctuation">(</span>temperature<span class="token punctuation">,</span> <span class="token string">'type'</span><span class="token operator">=</span><span class="token string">'avg'</span><span class="token punctuation">,</span><span class="token string">'proportion'</span><span class="token operator">=</span><span class="token string">'0.1'</span><span class="token punctuation">)</span> <span class="token keyword">as</span> agg_avg<span class="token punctuation">,</span> equal_size_bucket_agg_sample<span class="token punctuation">(</span>temperature<span class="token punctuation">,</span> <span class="token string">'type'</span><span class="token operator">=</span><span class="token string">'max'</span><span class="token punctuation">,</span><span class="token string">'proportion'</span><span class="token operator">=</span><span class="token string">'0.1'</span><span class="token punctuation">)</span> <span class="token keyword">as</span> agg_max<span class="token punctuation">,</span> equal_size_bucket_agg_sample<span class="token punctuation">(</span>temperature<span class="token punctuation">,</span><span class="token string">'type'</span><span class="token operator">=</span><span class="token string">'min'</span><span class="token punctuation">,</span><span class="token string">'proportion'</span><span class="token operator">=</span><span class="token string">'0.1'</span><span class="token punctuation">)</span> <span class="token keyword">as</span> agg_min<span class="token punctuation">,</span> equal_size_bucket_agg_sample<span class="token punctuation">(</span>temperature<span class="token punctuation">,</span> <span class="token string">'type'</span><span class="token operator">=</span><span class="token string">'sum'</span><span class="token punctuation">,</span><span class="token string">'proportion'</span><span class="token operator">=</span><span class="token string">'0.1'</span><span class="token punctuation">)</span> <span class="token keyword">as</span> agg_sum<span class="token punctuation">,</span> equal_size_bucket_agg_sample<span class="token punctuation">(</span>temperature<span class="token punctuation">,</span> <span class="token string">'type'</span><span class="token operator">=</span><span class="token string">'extreme'</span><span class="token punctuation">,</span><span class="token string">'proportion'</span><span class="token operator">=</span><span class="token string">'0.1'</span><span class="token punctuation">)</span> <span class="token keyword">as</span> agg_extreme<span class="token punctuation">,</span> equal_size_bucket_agg_sample<span class="token punctuation">(</span>temperature<span class="token punctuation">,</span> <span class="token string">'type'</span><span class="token operator">=</span><span class="token string">'variance'</span><span class="token punctuation">,</span><span class="token string">'proportion'</span><span class="token operator">=</span><span class="token string">'0.1'</span><span class="token punctuation">)</span> <span class="token keyword">as</span> agg_variance <span class="token keyword">from</span> root<span class="token punctuation">.</span>ln<span class="token punctuation">.</span>wf01<span class="token punctuation">.</span>wt01<span class="token punctuation">;</span> |
| </code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></div></div><p>结果:</p><div class="language-text line-numbers-mode" data-ext="text" data-title="text"><pre class="language-text"><code>+-----------------------------+-----------------+-------+-------+-------+-----------+------------+ |
| | Time| agg_avg|agg_max|agg_min|agg_sum|agg_extreme|agg_variance| |
| +-----------------------------+-----------------+-------+-------+-------+-----------+------------+ |
| |1970-01-01T08:00:00.000+08:00| 4.5| 9.0| 0.0| 45.0| 9.0| 8.25| |
| |1970-01-01T08:00:00.010+08:00| 14.5| 19.0| 10.0| 145.0| 19.0| 8.25| |
| |1970-01-01T08:00:00.020+08:00| 24.5| 29.0| 20.0| 245.0| 29.0| 8.25| |
| |1970-01-01T08:00:00.030+08:00| 34.5| 39.0| 30.0| 345.0| 39.0| 8.25| |
| |1970-01-01T08:00:00.040+08:00| 44.5| 49.0| 40.0| 445.0| 49.0| 8.25| |
| |1970-01-01T08:00:00.050+08:00| 54.5| 59.0| 50.0| 545.0| 59.0| 8.25| |
| |1970-01-01T08:00:00.060+08:00| 64.5| 69.0| 60.0| 645.0| 69.0| 8.25| |
| |1970-01-01T08:00:00.070+08:00|74.50000000000001| 79.0| 70.0| 745.0| 79.0| 8.25| |
| |1970-01-01T08:00:00.080+08:00| 84.5| 89.0| 80.0| 845.0| 89.0| 8.25| |
| |1970-01-01T08:00:00.090+08:00| 94.5| 99.0| 90.0| 945.0| 99.0| 8.25| |
| +-----------------------------+-----------------+-------+-------+-------+-----------+------------+ |
| Total line number = 10 |
| It costs 0.044s |
| </code></pre><div class="line-numbers" aria-hidden="true"><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 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><h4 id="等数量分桶-m4-采样" tabindex="-1"><a class="header-anchor" href="#等数量分桶-m4-采样"><span>等数量分桶 M4 采样</span></a></h4><h5 id="函数简介-2" tabindex="-1"><a class="header-anchor" href="#函数简介-2"><span>函数简介</span></a></h5><p>采用M4采样法对输入序列进行采样。即对于每个桶采样首、尾、最小和最大值。</p><table><thead><tr><th>函数名</th><th>可接收的输入序列类型</th><th>必要的属性参数</th><th>输出序列类型</th><th>功能类型</th></tr></thead><tbody><tr><td>EQUAL_SIZE_BUCKET_M4_SAMPLE</td><td>INT32 / INT64 / FLOAT / DOUBLE</td><td><code>proportion</code>取值范围为<code>(0, 1]</code>，默认为<code>0.1</code></td><td>INT32 / INT64 / FLOAT / DOUBLE</td><td>返回符合采样比例的等分桶M4采样</td></tr></tbody></table><h5 id="使用示例-2" tabindex="-1"><a class="header-anchor" href="#使用示例-2"><span>使用示例</span></a></h5><p>输入序列:<code>root.ln.wf01.wt01.temperature</code>从<code>0.0-99.0</code>共<code>100</code>条有序数据，同等分桶随机采样的测试数据。</p><p>sql:</p><div class="language-sql line-numbers-mode" data-ext="sql" data-title="sql"><pre class="language-sql"><code><span class="token keyword">select</span> equal_size_bucket_m4_sample<span class="token punctuation">(</span>temperature<span class="token punctuation">,</span> <span class="token string">'proportion'</span><span class="token operator">=</span><span class="token string">'0.1'</span><span class="token punctuation">)</span> <span class="token keyword">as</span> M4_sample <span class="token keyword">from</span> root<span class="token punctuation">.</span>ln<span class="token punctuation">.</span>wf01<span class="token punctuation">.</span>wt01<span class="token punctuation">;</span> |
| </code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></div></div><p>结果:</p><div class="language-text line-numbers-mode" data-ext="text" data-title="text"><pre class="language-text"><code>+-----------------------------+---------+ |
| | Time|M4_sample| |
| +-----------------------------+---------+ |
| |1970-01-01T08:00:00.000+08:00| 0.0| |
| |1970-01-01T08:00:00.001+08:00| 1.0| |
| |1970-01-01T08:00:00.038+08:00| 38.0| |
| |1970-01-01T08:00:00.039+08:00| 39.0| |
| |1970-01-01T08:00:00.040+08:00| 40.0| |
| |1970-01-01T08:00:00.041+08:00| 41.0| |
| |1970-01-01T08:00:00.078+08:00| 78.0| |
| |1970-01-01T08:00:00.079+08:00| 79.0| |
| |1970-01-01T08:00:00.080+08:00| 80.0| |
| |1970-01-01T08:00:00.081+08:00| 81.0| |
| |1970-01-01T08:00:00.098+08:00| 98.0| |
| |1970-01-01T08:00:00.099+08:00| 99.0| |
| +-----------------------------+---------+ |
| Total line number = 12 |
| It costs 0.065s |
| </code></pre><div class="line-numbers" aria-hidden="true"><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 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><h4 id="等数量分桶离群值采样" tabindex="-1"><a class="header-anchor" href="#等数量分桶离群值采样"><span>等数量分桶离群值采样</span></a></h4><h5 id="函数简介-3" tabindex="-1"><a class="header-anchor" href="#函数简介-3"><span>函数简介</span></a></h5><p>本函数对输入序列进行等数量分桶离群值采样，即根据用户给定的降采样比例和桶内采样个数将输入序列按固定点数等分为若干桶，在每个桶内通过给定的离群值采样方法进行采样。</p><table><thead><tr><th>函数名</th><th>可接收的输入序列类型</th><th>必要的属性参数</th><th>输出序列类型</th><th>功能类型</th></tr></thead><tbody><tr><td>EQUAL_SIZE_BUCKET_OUTLIER_SAMPLE</td><td>INT32 / INT64 / FLOAT / DOUBLE</td><td><code>proportion</code>取值范围为<code>(0, 1]</code>，默认为<code>0.1</code><br><code>type</code>取值为<code>avg</code>或<code>stendis</code>或<code>cos</code>或<code>prenextdis</code>，默认为<code>avg</code><br><code>number</code>取值应大于0，默认<code>3</code></td><td>INT32 / INT64 / FLOAT / DOUBLE</td><td>返回符合采样比例和桶内采样个数的等分桶离群值采样</td></tr></tbody></table><p>参数说明</p><ul><li><code>proportion</code>: 采样比例 <ul><li><code>number</code>: 每个桶内的采样个数，默认<code>3</code></li></ul></li><li><code>type</code>: 离群值采样方法，取值为 <ul><li><code>avg</code>: 取桶内数据点的平均值，并根据采样比例，找到距离均值最远的<code>top number</code>个</li><li><code>stendis</code>: 取桶内每一个数据点距离桶的首末数据点连成直线的垂直距离，并根据采样比例，找到距离最大的<code>top number</code>个</li><li><code>cos</code>: 设桶内一个数据点为b，b左边的数据点为a，b右边的数据点为c，则取ab与bc向量的夹角的余弦值，值越小，说明形成的角度越大，越可能是异常值。找到cos值最小的<code>top number</code>个</li><li><code>prenextdis</code>: 设桶内一个数据点为b，b左边的数据点为a，b右边的数据点为c，则取ab与bc的长度之和作为衡量标准，和越大越可能是异常值，找到最大的<code>top number</code>个</li></ul></li></ul><h5 id="使用示例-3" tabindex="-1"><a class="header-anchor" href="#使用示例-3"><span>使用示例</span></a></h5><p>测试数据:<code>root.ln.wf01.wt01.temperature</code>从<code>0.0-99.0</code>共<code>100</code>条数据，其中为了加入离群值，我们使得个位数为5的值自增100。</p><div class="language-text line-numbers-mode" data-ext="text" data-title="text"><pre class="language-text"><code>IoTDB> select temperature from root.ln.wf01.wt01; |
| +-----------------------------+-----------------------------+ |
| | Time|root.ln.wf01.wt01.temperature| |
| +-----------------------------+-----------------------------+ |
| |1970-01-01T08:00:00.000+08:00| 0.0| |
| |1970-01-01T08:00:00.001+08:00| 1.0| |
| |1970-01-01T08:00:00.002+08:00| 2.0| |
| |1970-01-01T08:00:00.003+08:00| 3.0| |
| |1970-01-01T08:00:00.004+08:00| 4.0| |
| |1970-01-01T08:00:00.005+08:00| 105.0| |
| |1970-01-01T08:00:00.006+08:00| 6.0| |
| |1970-01-01T08:00:00.007+08:00| 7.0| |
| |1970-01-01T08:00:00.008+08:00| 8.0| |
| |1970-01-01T08:00:00.009+08:00| 9.0| |
| |1970-01-01T08:00:00.010+08:00| 10.0| |
| |1970-01-01T08:00:00.011+08:00| 11.0| |
| |1970-01-01T08:00:00.012+08:00| 12.0| |
| |1970-01-01T08:00:00.013+08:00| 13.0| |
| |1970-01-01T08:00:00.014+08:00| 14.0| |
| |1970-01-01T08:00:00.015+08:00| 115.0| |
| |1970-01-01T08:00:00.016+08:00| 16.0| |
| |.............................|.............................| |
| |1970-01-01T08:00:00.092+08:00| 92.0| |
| |1970-01-01T08:00:00.093+08:00| 93.0| |
| |1970-01-01T08:00:00.094+08:00| 94.0| |
| |1970-01-01T08:00:00.095+08:00| 195.0| |
| |1970-01-01T08:00:00.096+08:00| 96.0| |
| |1970-01-01T08:00:00.097+08:00| 97.0| |
| |1970-01-01T08:00:00.098+08:00| 98.0| |
| |1970-01-01T08:00:00.099+08:00| 99.0| |
| +-----------------------------+-----------------------------+ |
| </code></pre><div class="line-numbers" aria-hidden="true"><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 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 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><p>sql:</p><div class="language-sql line-numbers-mode" data-ext="sql" data-title="sql"><pre class="language-sql"><code><span class="token keyword">select</span> equal_size_bucket_outlier_sample<span class="token punctuation">(</span>temperature<span class="token punctuation">,</span> <span class="token string">'proportion'</span><span class="token operator">=</span><span class="token string">'0.1'</span><span class="token punctuation">,</span> <span class="token string">'type'</span><span class="token operator">=</span><span class="token string">'avg'</span><span class="token punctuation">,</span> <span class="token string">'number'</span><span class="token operator">=</span><span class="token string">'2'</span><span class="token punctuation">)</span> <span class="token keyword">as</span> outlier_avg_sample<span class="token punctuation">,</span> equal_size_bucket_outlier_sample<span class="token punctuation">(</span>temperature<span class="token punctuation">,</span> <span class="token string">'proportion'</span><span class="token operator">=</span><span class="token string">'0.1'</span><span class="token punctuation">,</span> <span class="token string">'type'</span><span class="token operator">=</span><span class="token string">'stendis'</span><span class="token punctuation">,</span> <span class="token string">'number'</span><span class="token operator">=</span><span class="token string">'2'</span><span class="token punctuation">)</span> <span class="token keyword">as</span> outlier_stendis_sample<span class="token punctuation">,</span> equal_size_bucket_outlier_sample<span class="token punctuation">(</span>temperature<span class="token punctuation">,</span> <span class="token string">'proportion'</span><span class="token operator">=</span><span class="token string">'0.1'</span><span class="token punctuation">,</span> <span class="token string">'type'</span><span class="token operator">=</span><span class="token string">'cos'</span><span class="token punctuation">,</span> <span class="token string">'number'</span><span class="token operator">=</span><span class="token string">'2'</span><span class="token punctuation">)</span> <span class="token keyword">as</span> outlier_cos_sample<span class="token punctuation">,</span> equal_size_bucket_outlier_sample<span class="token punctuation">(</span>temperature<span class="token punctuation">,</span> <span class="token string">'proportion'</span><span class="token operator">=</span><span class="token string">'0.1'</span><span class="token punctuation">,</span> <span class="token string">'type'</span><span class="token operator">=</span><span class="token string">'prenextdis'</span><span class="token punctuation">,</span> <span class="token string">'number'</span><span class="token operator">=</span><span class="token string">'2'</span><span class="token punctuation">)</span> <span class="token keyword">as</span> outlier_prenextdis_sample <span class="token keyword">from</span> root<span class="token punctuation">.</span>ln<span class="token punctuation">.</span>wf01<span class="token punctuation">.</span>wt01<span class="token punctuation">;</span> |
| </code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></div></div><p>结果:</p><div class="language-text line-numbers-mode" data-ext="text" data-title="text"><pre class="language-text"><code>+-----------------------------+------------------+----------------------+------------------+-------------------------+ |
| | Time|outlier_avg_sample|outlier_stendis_sample|outlier_cos_sample|outlier_prenextdis_sample| |
| +-----------------------------+------------------+----------------------+------------------+-------------------------+ |
| |1970-01-01T08:00:00.005+08:00| 105.0| 105.0| 105.0| 105.0| |
| |1970-01-01T08:00:00.015+08:00| 115.0| 115.0| 115.0| 115.0| |
| |1970-01-01T08:00:00.025+08:00| 125.0| 125.0| 125.0| 125.0| |
| |1970-01-01T08:00:00.035+08:00| 135.0| 135.0| 135.0| 135.0| |
| |1970-01-01T08:00:00.045+08:00| 145.0| 145.0| 145.0| 145.0| |
| |1970-01-01T08:00:00.055+08:00| 155.0| 155.0| 155.0| 155.0| |
| |1970-01-01T08:00:00.065+08:00| 165.0| 165.0| 165.0| 165.0| |
| |1970-01-01T08:00:00.075+08:00| 175.0| 175.0| 175.0| 175.0| |
| |1970-01-01T08:00:00.085+08:00| 185.0| 185.0| 185.0| 185.0| |
| |1970-01-01T08:00:00.095+08:00| 195.0| 195.0| 195.0| 195.0| |
| +-----------------------------+------------------+----------------------+------------------+-------------------------+ |
| Total line number = 10 |
| It costs 0.041s |
| </code></pre><div class="line-numbers" aria-hidden="true"><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 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="m4函数" tabindex="-1"><a class="header-anchor" href="#m4函数"><span>M4函数</span></a></h3><h4 id="函数简介-4" tabindex="-1"><a class="header-anchor" href="#函数简介-4"><span>函数简介</span></a></h4><p>M4用于在窗口内采样第一个点（<code>first</code>）、最后一个点（<code>last</code>）、最小值点（<code>bottom</code>）、最大值点（<code>top</code>）：</p><ul><li>第一个点是拥有这个窗口内最小时间戳的点；</li><li>最后一个点是拥有这个窗口内最大时间戳的点；</li><li>最小值点是拥有这个窗口内最小值的点（如果有多个这样的点，M4只返回其中一个）；</li><li>最大值点是拥有这个窗口内最大值的点（如果有多个这样的点，M4只返回其中一个）。</li></ul><img src="https://alioss.timecho.com/docs/img/github/198178733-a0919d17-0663-4672-9c4f-1efad6f463c2.png" alt="image" style="zoom:50%;"><table><thead><tr><th>函数名</th><th>可接收的输入序列类型</th><th>属性参数</th><th>输出序列类型</th><th>功能类型</th></tr></thead><tbody><tr><td>M4</td><td>INT32 / INT64 / FLOAT / DOUBLE</td><td>包含固定点数的窗口和滑动时间窗口使用不同的属性参数。包含固定点数的窗口使用属性<code>windowSize</code>和<code>slidingStep</code>。滑动时间窗口使用属性<code>timeInterval</code>、<code>slidingStep</code>、<code>displayWindowBegin</code>和<code>displayWindowEnd</code>。更多细节见下文。</td><td>INT32 / INT64 / FLOAT / DOUBLE</td><td>返回每个窗口内的第一个点（<code>first</code>）、最后一个点（<code>last</code>）、最小值点（<code>bottom</code>）、最大值点（<code>top</code>）。在一个窗口内的聚合点输出之前，M4会将它们按照时间戳递增排序并且去重。</td></tr></tbody></table><h4 id="属性参数" tabindex="-1"><a class="header-anchor" href="#属性参数"><span>属性参数</span></a></h4><p><strong>(1) 包含固定点数的窗口（SlidingSizeWindowAccessStrategy）使用的属性参数:</strong></p><ul><li><code>windowSize</code>: 一个窗口内的点数。Int数据类型。必需的属性参数。</li><li><code>slidingStep</code>: 按照设定的点数来滑动窗口。Int数据类型。可选的属性参数；如果没有设置，默认取值和<code>windowSize</code>一样。</li></ul><img src="https://alioss.timecho.com/docs/img/github/198181449-00d563c8-7bce-4ecd-a031-ec120ca42c3f.png" alt="image" style="zoom:50%;"><p><em>(图片来源: <a href="https://iotdb.apache.org/UserGuide/Master/Process-Data/UDF-User-Defined-Function.html#udtf-user-defined-timeseries-generating-function" target="_blank" rel="noopener noreferrer">https://iotdb.apache.org/UserGuide/Master/Process-Data/UDF-User-Defined-Function.html#udtf-user-defined-timeseries-generating-function<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>)</em></p><p><strong>(2) 滑动时间窗口（SlidingTimeWindowAccessStrategy）使用的属性参数:</strong></p><ul><li><code>timeInterval</code>: 一个窗口的时间长度。Long数据类型。必需的属性参数。</li><li><code>slidingStep</code>: 按照设定的时长来滑动窗口。Long数据类型。可选的属性参数；如果没有设置，默认取值和<code>timeInterval</code>一样。</li><li><code>displayWindowBegin</code>: 窗口滑动的起始时间戳位置（包含在内）。Long数据类型。可选的属性参数；如果没有设置，默认取值为Long.MIN_VALUE，意为使用输入的时间序列的第一个点的时间戳作为窗口滑动的起始时间戳位置。</li><li><code>displayWindowEnd</code>: 结束时间限制（不包含在内；本质上和<code>WHERE time < displayWindowEnd</code>起的效果是一样的)。Long数据类型。可选的属性参数；如果没有设置，默认取值为Long.MAX_VALUE，意为除了输入的时间序列自身数据读取完毕之外没有增加额外的结束时间过滤条件限制。</li></ul><img src="https://alioss.timecho.com/docs/img/github/198183015-93b56644-3330-4acf-ae9e-d718a02b5f4c.png" alt="groupBy window" style="zoom:67%;"><p><em>(图片来源: <a href="https://iotdb.apache.org/UserGuide/Master/Query-Data/Aggregate-Query.html#downsampling-aggregate-query" target="_blank" rel="noopener noreferrer">https://iotdb.apache.org/UserGuide/Master/Query-Data/Aggregate-Query.html#downsampling-aggregate-query<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>)</em></p><h4 id="使用示例-4" tabindex="-1"><a class="header-anchor" href="#使用示例-4"><span>使用示例</span></a></h4><p>输入的时间序列：</p><div class="language-sql line-numbers-mode" data-ext="sql" data-title="sql"><pre class="language-sql"><code><span class="token operator">+</span><span class="token comment">-----------------------------+------------------+</span> |
| <span class="token operator">|</span> <span class="token keyword">Time</span><span class="token operator">|</span>root<span class="token punctuation">.</span>vehicle<span class="token punctuation">.</span>d1<span class="token punctuation">.</span>s1<span class="token operator">|</span> |
| <span class="token operator">+</span><span class="token comment">-----------------------------+------------------+</span> |
| <span class="token operator">|</span><span class="token number">1970</span><span class="token operator">-</span><span class="token number">01</span><span class="token operator">-</span><span class="token number">01</span>T08:<span class="token number">00</span>:<span class="token number">00.001</span><span class="token operator">+</span><span class="token number">08</span>:<span class="token number">00</span><span class="token operator">|</span> <span class="token number">5.0</span><span class="token operator">|</span> |
| <span class="token operator">|</span><span class="token number">1970</span><span class="token operator">-</span><span class="token number">01</span><span class="token operator">-</span><span class="token number">01</span>T08:<span class="token number">00</span>:<span class="token number">00.002</span><span class="token operator">+</span><span class="token number">08</span>:<span class="token number">00</span><span class="token operator">|</span> <span class="token number">15.0</span><span class="token operator">|</span> |
| <span class="token operator">|</span><span class="token number">1970</span><span class="token operator">-</span><span class="token number">01</span><span class="token operator">-</span><span class="token number">01</span>T08:<span class="token number">00</span>:<span class="token number">00.005</span><span class="token operator">+</span><span class="token number">08</span>:<span class="token number">00</span><span class="token operator">|</span> <span class="token number">10.0</span><span class="token operator">|</span> |
| <span class="token operator">|</span><span class="token number">1970</span><span class="token operator">-</span><span class="token number">01</span><span class="token operator">-</span><span class="token number">01</span>T08:<span class="token number">00</span>:<span class="token number">00.008</span><span class="token operator">+</span><span class="token number">08</span>:<span class="token number">00</span><span class="token operator">|</span> <span class="token number">8.0</span><span class="token operator">|</span> |
| <span class="token operator">|</span><span class="token number">1970</span><span class="token operator">-</span><span class="token number">01</span><span class="token operator">-</span><span class="token number">01</span>T08:<span class="token number">00</span>:<span class="token number">00.010</span><span class="token operator">+</span><span class="token number">08</span>:<span class="token number">00</span><span class="token operator">|</span> <span class="token number">30.0</span><span class="token operator">|</span> |
| <span class="token operator">|</span><span class="token number">1970</span><span class="token operator">-</span><span class="token number">01</span><span class="token operator">-</span><span class="token number">01</span>T08:<span class="token number">00</span>:<span class="token number">00.020</span><span class="token operator">+</span><span class="token number">08</span>:<span class="token number">00</span><span class="token operator">|</span> <span class="token number">20.0</span><span class="token operator">|</span> |
| <span class="token operator">|</span><span class="token number">1970</span><span class="token operator">-</span><span class="token number">01</span><span class="token operator">-</span><span class="token number">01</span>T08:<span class="token number">00</span>:<span class="token number">00.025</span><span class="token operator">+</span><span class="token number">08</span>:<span class="token number">00</span><span class="token operator">|</span> <span class="token number">8.0</span><span class="token operator">|</span> |
| <span class="token operator">|</span><span class="token number">1970</span><span class="token operator">-</span><span class="token number">01</span><span class="token operator">-</span><span class="token number">01</span>T08:<span class="token number">00</span>:<span class="token number">00.027</span><span class="token operator">+</span><span class="token number">08</span>:<span class="token number">00</span><span class="token operator">|</span> <span class="token number">20.0</span><span class="token operator">|</span> |
| <span class="token operator">|</span><span class="token number">1970</span><span class="token operator">-</span><span class="token number">01</span><span class="token operator">-</span><span class="token number">01</span>T08:<span class="token number">00</span>:<span class="token number">00.030</span><span class="token operator">+</span><span class="token number">08</span>:<span class="token number">00</span><span class="token operator">|</span> <span class="token number">40.0</span><span class="token operator">|</span> |
| <span class="token operator">|</span><span class="token number">1970</span><span class="token operator">-</span><span class="token number">01</span><span class="token operator">-</span><span class="token number">01</span>T08:<span class="token number">00</span>:<span class="token number">00.033</span><span class="token operator">+</span><span class="token number">08</span>:<span class="token number">00</span><span class="token operator">|</span> <span class="token number">9.0</span><span class="token operator">|</span> |
| <span class="token operator">|</span><span class="token number">1970</span><span class="token operator">-</span><span class="token number">01</span><span class="token operator">-</span><span class="token number">01</span>T08:<span class="token number">00</span>:<span class="token number">00.035</span><span class="token operator">+</span><span class="token number">08</span>:<span class="token number">00</span><span class="token operator">|</span> <span class="token number">10.0</span><span class="token operator">|</span> |
| <span class="token operator">|</span><span class="token number">1970</span><span class="token operator">-</span><span class="token number">01</span><span class="token operator">-</span><span class="token number">01</span>T08:<span class="token number">00</span>:<span class="token number">00.040</span><span class="token operator">+</span><span class="token number">08</span>:<span class="token number">00</span><span class="token operator">|</span> <span class="token number">20.0</span><span class="token operator">|</span> |
| <span class="token operator">|</span><span class="token number">1970</span><span class="token operator">-</span><span class="token number">01</span><span class="token operator">-</span><span class="token number">01</span>T08:<span class="token number">00</span>:<span class="token number">00.045</span><span class="token operator">+</span><span class="token number">08</span>:<span class="token number">00</span><span class="token operator">|</span> <span class="token number">30.0</span><span class="token operator">|</span> |
| <span class="token operator">|</span><span class="token number">1970</span><span class="token operator">-</span><span class="token number">01</span><span class="token operator">-</span><span class="token number">01</span>T08:<span class="token number">00</span>:<span class="token number">00.052</span><span class="token operator">+</span><span class="token number">08</span>:<span class="token number">00</span><span class="token operator">|</span> <span class="token number">8.0</span><span class="token operator">|</span> |
| <span class="token operator">|</span><span class="token number">1970</span><span class="token operator">-</span><span class="token number">01</span><span class="token operator">-</span><span class="token number">01</span>T08:<span class="token number">00</span>:<span class="token number">00.054</span><span class="token operator">+</span><span class="token number">08</span>:<span class="token number">00</span><span class="token operator">|</span> <span class="token number">18.0</span><span class="token operator">|</span> |
| <span class="token operator">+</span><span class="token comment">-----------------------------+------------------+</span> |
| </code></pre><div class="line-numbers" aria-hidden="true"><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 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><p>查询语句1：</p><div class="language-sql line-numbers-mode" data-ext="sql" data-title="sql"><pre class="language-sql"><code><span class="token keyword">select</span> M4<span class="token punctuation">(</span>s1<span class="token punctuation">,</span><span class="token string">'timeInterval'</span><span class="token operator">=</span><span class="token string">'25'</span><span class="token punctuation">,</span><span class="token string">'displayWindowBegin'</span><span class="token operator">=</span><span class="token string">'0'</span><span class="token punctuation">,</span><span class="token string">'displayWindowEnd'</span><span class="token operator">=</span><span class="token string">'100'</span><span class="token punctuation">)</span> <span class="token keyword">from</span> root<span class="token punctuation">.</span>vehicle<span class="token punctuation">.</span>d1 |
| </code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></div></div><p>输出结果1：</p><div class="language-sql line-numbers-mode" data-ext="sql" data-title="sql"><pre class="language-sql"><code><span class="token operator">+</span><span class="token comment">-----------------------------+-----------------------------------------------------------------------------------------------+</span> |
| <span class="token operator">|</span> <span class="token keyword">Time</span><span class="token operator">|</span>M4<span class="token punctuation">(</span>root<span class="token punctuation">.</span>vehicle<span class="token punctuation">.</span>d1<span class="token punctuation">.</span>s1<span class="token punctuation">,</span> <span class="token string">"timeInterval"</span><span class="token operator">=</span><span class="token string">"25"</span><span class="token punctuation">,</span> <span class="token string">"displayWindowBegin"</span><span class="token operator">=</span><span class="token string">"0"</span><span class="token punctuation">,</span> <span class="token string">"displayWindowEnd"</span><span class="token operator">=</span><span class="token string">"100"</span><span class="token punctuation">)</span><span class="token operator">|</span> |
| <span class="token operator">+</span><span class="token comment">-----------------------------+-----------------------------------------------------------------------------------------------+</span> |
| <span class="token operator">|</span><span class="token number">1970</span><span class="token operator">-</span><span class="token number">01</span><span class="token operator">-</span><span class="token number">01</span>T08:<span class="token number">00</span>:<span class="token number">00.001</span><span class="token operator">+</span><span class="token number">08</span>:<span class="token number">00</span><span class="token operator">|</span> <span class="token number">5.0</span><span class="token operator">|</span> |
| <span class="token operator">|</span><span class="token number">1970</span><span class="token operator">-</span><span class="token number">01</span><span class="token operator">-</span><span class="token number">01</span>T08:<span class="token number">00</span>:<span class="token number">00.010</span><span class="token operator">+</span><span class="token number">08</span>:<span class="token number">00</span><span class="token operator">|</span> <span class="token number">30.0</span><span class="token operator">|</span> |
| <span class="token operator">|</span><span class="token number">1970</span><span class="token operator">-</span><span class="token number">01</span><span class="token operator">-</span><span class="token number">01</span>T08:<span class="token number">00</span>:<span class="token number">00.020</span><span class="token operator">+</span><span class="token number">08</span>:<span class="token number">00</span><span class="token operator">|</span> <span class="token number">20.0</span><span class="token operator">|</span> |
| <span class="token operator">|</span><span class="token number">1970</span><span class="token operator">-</span><span class="token number">01</span><span class="token operator">-</span><span class="token number">01</span>T08:<span class="token number">00</span>:<span class="token number">00.025</span><span class="token operator">+</span><span class="token number">08</span>:<span class="token number">00</span><span class="token operator">|</span> <span class="token number">8.0</span><span class="token operator">|</span> |
| <span class="token operator">|</span><span class="token number">1970</span><span class="token operator">-</span><span class="token number">01</span><span class="token operator">-</span><span class="token number">01</span>T08:<span class="token number">00</span>:<span class="token number">00.030</span><span class="token operator">+</span><span class="token number">08</span>:<span class="token number">00</span><span class="token operator">|</span> <span class="token number">40.0</span><span class="token operator">|</span> |
| <span class="token operator">|</span><span class="token number">1970</span><span class="token operator">-</span><span class="token number">01</span><span class="token operator">-</span><span class="token number">01</span>T08:<span class="token number">00</span>:<span class="token number">00.045</span><span class="token operator">+</span><span class="token number">08</span>:<span class="token number">00</span><span class="token operator">|</span> <span class="token number">30.0</span><span class="token operator">|</span> |
| <span class="token operator">|</span><span class="token number">1970</span><span class="token operator">-</span><span class="token number">01</span><span class="token operator">-</span><span class="token number">01</span>T08:<span class="token number">00</span>:<span class="token number">00.052</span><span class="token operator">+</span><span class="token number">08</span>:<span class="token number">00</span><span class="token operator">|</span> <span class="token number">8.0</span><span class="token operator">|</span> |
| <span class="token operator">|</span><span class="token number">1970</span><span class="token operator">-</span><span class="token number">01</span><span class="token operator">-</span><span class="token number">01</span>T08:<span class="token number">00</span>:<span class="token number">00.054</span><span class="token operator">+</span><span class="token number">08</span>:<span class="token number">00</span><span class="token operator">|</span> <span class="token number">18.0</span><span class="token operator">|</span> |
| <span class="token operator">+</span><span class="token comment">-----------------------------+-----------------------------------------------------------------------------------------------+</span> |
| Total line number <span class="token operator">=</span> <span class="token number">8</span> |
| </code></pre><div class="line-numbers" aria-hidden="true"><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 class="line-number"></div><div class="line-number"></div></div></div><p>查询语句2：</p><div class="language-sql line-numbers-mode" data-ext="sql" data-title="sql"><pre class="language-sql"><code><span class="token keyword">select</span> M4<span class="token punctuation">(</span>s1<span class="token punctuation">,</span><span class="token string">'windowSize'</span><span class="token operator">=</span><span class="token string">'10'</span><span class="token punctuation">)</span> <span class="token keyword">from</span> root<span class="token punctuation">.</span>vehicle<span class="token punctuation">.</span>d1 |
| </code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></div></div><p>输出结果2：</p><div class="language-sql line-numbers-mode" data-ext="sql" data-title="sql"><pre class="language-sql"><code><span class="token operator">+</span><span class="token comment">-----------------------------+-----------------------------------------+</span> |
| <span class="token operator">|</span> <span class="token keyword">Time</span><span class="token operator">|</span>M4<span class="token punctuation">(</span>root<span class="token punctuation">.</span>vehicle<span class="token punctuation">.</span>d1<span class="token punctuation">.</span>s1<span class="token punctuation">,</span> <span class="token string">"windowSize"</span><span class="token operator">=</span><span class="token string">"10"</span><span class="token punctuation">)</span><span class="token operator">|</span> |
| <span class="token operator">+</span><span class="token comment">-----------------------------+-----------------------------------------+</span> |
| <span class="token operator">|</span><span class="token number">1970</span><span class="token operator">-</span><span class="token number">01</span><span class="token operator">-</span><span class="token number">01</span>T08:<span class="token number">00</span>:<span class="token number">00.001</span><span class="token operator">+</span><span class="token number">08</span>:<span class="token number">00</span><span class="token operator">|</span> <span class="token number">5.0</span><span class="token operator">|</span> |
| <span class="token operator">|</span><span class="token number">1970</span><span class="token operator">-</span><span class="token number">01</span><span class="token operator">-</span><span class="token number">01</span>T08:<span class="token number">00</span>:<span class="token number">00.030</span><span class="token operator">+</span><span class="token number">08</span>:<span class="token number">00</span><span class="token operator">|</span> <span class="token number">40.0</span><span class="token operator">|</span> |
| <span class="token operator">|</span><span class="token number">1970</span><span class="token operator">-</span><span class="token number">01</span><span class="token operator">-</span><span class="token number">01</span>T08:<span class="token number">00</span>:<span class="token number">00.033</span><span class="token operator">+</span><span class="token number">08</span>:<span class="token number">00</span><span class="token operator">|</span> <span class="token number">9.0</span><span class="token operator">|</span> |
| <span class="token operator">|</span><span class="token number">1970</span><span class="token operator">-</span><span class="token number">01</span><span class="token operator">-</span><span class="token number">01</span>T08:<span class="token number">00</span>:<span class="token number">00.035</span><span class="token operator">+</span><span class="token number">08</span>:<span class="token number">00</span><span class="token operator">|</span> <span class="token number">10.0</span><span class="token operator">|</span> |
| <span class="token operator">|</span><span class="token number">1970</span><span class="token operator">-</span><span class="token number">01</span><span class="token operator">-</span><span class="token number">01</span>T08:<span class="token number">00</span>:<span class="token number">00.045</span><span class="token operator">+</span><span class="token number">08</span>:<span class="token number">00</span><span class="token operator">|</span> <span class="token number">30.0</span><span class="token operator">|</span> |
| <span class="token operator">|</span><span class="token number">1970</span><span class="token operator">-</span><span class="token number">01</span><span class="token operator">-</span><span class="token number">01</span>T08:<span class="token number">00</span>:<span class="token number">00.052</span><span class="token operator">+</span><span class="token number">08</span>:<span class="token number">00</span><span class="token operator">|</span> <span class="token number">8.0</span><span class="token operator">|</span> |
| <span class="token operator">|</span><span class="token number">1970</span><span class="token operator">-</span><span class="token number">01</span><span class="token operator">-</span><span class="token number">01</span>T08:<span class="token number">00</span>:<span class="token number">00.054</span><span class="token operator">+</span><span class="token number">08</span>:<span class="token number">00</span><span class="token operator">|</span> <span class="token number">18.0</span><span class="token operator">|</span> |
| <span class="token operator">+</span><span class="token comment">-----------------------------+-----------------------------------------+</span> |
| Total line number <span class="token operator">=</span> <span class="token number">7</span> |
| </code></pre><div class="line-numbers" aria-hidden="true"><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 class="line-number"></div></div></div><h4 id="推荐的使用场景" tabindex="-1"><a class="header-anchor" href="#推荐的使用场景"><span>推荐的使用场景</span></a></h4><p><strong>(1) 使用场景：保留极端点的降采样</strong></p><p>由于M4为每个窗口聚合其第一个点（<code>first</code>）、最后一个点（<code>last</code>）、最小值点（<code>bottom</code>）、最大值点（<code>top</code>），因此M4通常保留了极值点，因此比其他下采样方法（如分段聚合近似 (PAA)）能更好地保留模式。如果你想对时间序列进行下采样并且希望保留极值点，你可以试试 M4。</p><p><strong>(2) 使用场景：基于数据缩约的大规模时间序列的零误差双色折线图可视化</strong></p><p>参考论文: <a href="http://www.vldb.org/pvldb/vol7/p797-jugel.pdf" target="_blank" rel="noopener noreferrer">"M4: A Visualization-Oriented Time Series Data Aggregation"<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>.</p><p>假设屏幕画布的像素宽乘高是<code>w*h</code>，假设时间序列root.vehicle.d1.s1要可视化的时间范围是<code>[tqs,tqe)</code>（在这个使用场景里面，需要请你自行将tqe自适应调整使得(tqe-tqs)是w的整数倍），那么落在第i个时间跨度<code>Ii=[tqs+(tqe-tqs)/w*(i-1),tqs+(tqe-tqs)/w*i)</code> 内的点将会被画在第i个像素列中，i=1,2,...,w。</p><p>于是从可视化驱动的角度出发，使用查询语句：<code>"select M4(s1,'timeInterval'='(tqe-tqs)/w','displayWindowBegin'='tqs','displayWindowEnd'='tqe') from root.vehicle.d1"</code>，来采集每个时间跨度内的第一个点（<code>first</code>）、最后一个点（<code>last</code>）、最小值点（<code>bottom</code>）、最大值点（<code>top</code>）。最终结果点数不会超过<code>4*w</code>个，使用这些聚合点画出来的折线图与使用原始数据画出来的图在像素级别上是完全一致的。</p><h4 id="和其它sql的功能比较" tabindex="-1"><a class="header-anchor" href="#和其它sql的功能比较"><span>和其它SQL的功能比较</span></a></h4><table><thead><tr><th>SQL</th><th>是否支持M4聚合</th><th>滑动窗口类型</th><th>示例</th><th>相关文档</th></tr></thead><tbody><tr><td>1. 带有Group By子句的内置聚合函数</td><td>不支持，缺少<code>BOTTOM_TIME</code>和<code>TOP_TIME</code>，即缺少最小值点和最大值点的时间戳。</td><td>Time Window</td><td><code>select count(status), max_value(temperature) from root.ln.wf01.wt01 group by ([2017-11-01 00:00:00, 2017-11-07 23:00:00), 3h, 1d)</code></td><td><a href="https://iotdb.apache.org/UserGuide/Master/Query-Data/Aggregate-Query.html#built-in-aggregate-functions" target="_blank" rel="noopener noreferrer">https://iotdb.apache.org/UserGuide/Master/Query-Data/Aggregate-Query.html#built-in-aggregate-functions<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> <br><a href="https://iotdb.apache.org/UserGuide/Master/Query-Data/Aggregate-Query.html#downsampling-aggregate-query" target="_blank" rel="noopener noreferrer">https://iotdb.apache.org/UserGuide/Master/Query-Data/Aggregate-Query.html#downsampling-aggregate-query<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></td></tr><tr><td>2. EQUAL_SIZE_BUCKET_M4_SAMPLE (内置UDF)</td><td>支持*</td><td>Size Window. <code>windowSize = 4*(int)(1/proportion)</code></td><td><code>select equal_size_bucket_m4_sample(temperature, 'proportion'='0.1') as M4_sample from root.ln.wf01.wt01</code></td><td><a href="https://iotdb.apache.org/UserGuide/Master/Query-Data/Select-Expression.html#time-series-generating-functions" target="_blank" rel="noopener noreferrer">https://iotdb.apache.org/UserGuide/Master/Query-Data/Select-Expression.html#time-series-generating-functions<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></td></tr><tr><td><strong>3. M4 (内置UDF)</strong></td><td>支持*</td><td>Size Window, Time Window</td><td>(1) Size Window: <code>select M4(s1,'windowSize'='10') from root.vehicle.d1</code> <br>(2) Time Window: <code>select M4(s1,'timeInterval'='25','displayWindowBegin'='0','displayWindowEnd'='100') from root.vehicle.d1</code></td><td>本文档</td></tr><tr><td>4. 扩展带有Group By子句的内置聚合函数来支持M4聚合</td><td>未实施</td><td>未实施</td><td>未实施</td><td>未实施</td></tr></tbody></table><p>进一步比较<code>EQUAL_SIZE_BUCKET_M4_SAMPLE</code>和<code>M4</code>：</p><p><strong>(1) 不同的M4聚合函数定义：</strong></p><p>在每个窗口内，<code>EQUAL_SIZE_BUCKET_M4_SAMPLE</code>从排除了第一个点和最后一个点之后剩余的点中提取最小值点和最大值点。</p><p>而<code>M4</code>则是从窗口内所有点中（包括第一个点和最后一个点）提取最小值点和最大值点，这个定义与元数据中保存的<code>max_value</code>和<code>min_value</code>的语义更加一致。</p><p>值得注意的是，在一个窗口内的聚合点输出之前，<code>EQUAL_SIZE_BUCKET_M4_SAMPLE</code>和<code>M4</code>都会将它们按照时间戳递增排序并且去重。</p><p><strong>(2) 不同的滑动窗口：</strong></p><p><code>EQUAL_SIZE_BUCKET_M4_SAMPLE</code>使用SlidingSizeWindowAccessStrategy，并且通过采样比例（<code>proportion</code>）来间接控制窗口点数（<code>windowSize</code>)，转换公式是<code>windowSize = 4*(int)(1/proportion)</code>。</p><p><code>M4</code>支持两种滑动窗口：SlidingSizeWindowAccessStrategy和SlidingTimeWindowAccessStrategy，并且<code>M4</code>通过相应的参数直接控制窗口的点数或者时长。</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/V1.1.x/Operators-Functions/Sample.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/V1.1.x/Operators-Functions/Variation-Trend.html" aria-label="趋势计算"><div class="hint"><span class="arrow start"></span>上一页</div><div class="link"><!---->趋势计算</div></a><a class="route-link nav-link next" href="/zh/UserGuide/V1.1.x/Operators-Functions/Time-Series.html" aria-label="时间序列处理"><div class="hint">下一页<span class="arrow end"></span></div><div class="link">时间序列处理<!----></div></a></nav><!----><!--[--><!----><!--]--><!--]--></main><!--]--><footer style="padding-bottom:2rem;"><span id="doc-version" style="display:none;">rel/1.1</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> |
| <script type="module" src="/assets/app-DrPcRZG6.js" defer></script> |
| </body> |
| </html> |
