| <!doctype html> |
| <html lang="en-US" 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.14" /> |
| <meta name="theme" content="VuePress Theme Hope 2.0.0-rc.52" /> |
| <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="zh-cn" href="https://iotdb.apache.org/zh/UserGuide/latest/Basic-Concept/Cluster-data-partitioning.html"><meta property="og:url" content="https://iotdb.apache.org/UserGuide/latest/Basic-Concept/Cluster-data-partitioning.html"><meta property="og:site_name" content="IoTDB Website"><meta property="og:title" content="Load Balance"><meta property="og:description" content="Load Balance This document introduces the partitioning strategies and load balance strategies in IoTDB. According to the characteristics of time series data, IoTDB partitions th..."><meta property="og:type" content="article"><meta property="og:locale" content="en-US"><meta property="og:locale:alternate" content="zh-CN"><meta property="og:updated_time" content="2024-10-04T00:18:32.000Z"><meta property="article:modified_time" content="2024-10-04T00:18:32.000Z"><script type="application/ld+json">{"@context":"https://schema.org","@type":"Article","headline":"Load Balance","image":[""],"dateModified":"2024-10-04T00:18:32.000Z","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>Load Balance | IoTDB Website</title><meta name="description" content="Load Balance This document introduces the partitioning strategies and load balance strategies in IoTDB. According to the characteristics of time series data, IoTDB partitions th..."> |
| <link rel="preload" href="/assets/style-DNdyb_f0.css" as="style"><link rel="stylesheet" href="/assets/style-DNdyb_f0.css"> |
| <link rel="modulepreload" href="/assets/app-BRi6R9vN.js"><link rel="modulepreload" href="/assets/Cluster-data-partitioning.html-CdwGzm_4.js"> |
| |
| </head> |
| <body> |
| <div id="app"><!--[--><!--[--><!--[--><span tabindex="-1"></span><a href="#main-content" class="vp-skip-link sr-only">Skip to main content</a><!--]--><!--[--><div class="theme-container external-link-icon pure has-toc"><!--[--><header id="navbar" class="vp-navbar"><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="/"><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="Search"><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">Search</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="vp-dropdown-wrapper"><button type="button" class="vp-dropdown-title" aria-label="Documentation"><!--[--><!---->Documentation<!--]--><span class="arrow"></span><ul class="vp-dropdown"><li class="vp-dropdown-item"><a class="route-link auto-link" href="/UserGuide/latest/QuickStart/QuickStart_apache.html" aria-label="v1.3.0/1/2"><!---->v1.3.0/1/2<!----></a></li><li class="vp-dropdown-item"><a class="route-link auto-link" href="/UserGuide/V1.2.x/QuickStart/QuickStart.html" aria-label="v1.2.x"><!---->v1.2.x<!----></a></li><li class="vp-dropdown-item"><a class="route-link auto-link" href="/UserGuide/V1.1.x/QuickStart/QuickStart.html" aria-label="v1.1.x"><!---->v1.1.x<!----></a></li><li class="vp-dropdown-item"><a class="route-link auto-link" href="/UserGuide/V1.0.x/QuickStart/QuickStart.html" aria-label="v1.0.x"><!---->v1.0.x<!----></a></li><li class="vp-dropdown-item"><a class="route-link auto-link" href="/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 class="auto-link external-link" href="https://cwiki.apache.org/confluence/display/IOTDB/System+Design" aria-label="Design" rel="noopener noreferrer" target="_blank"><!---->Design<!----></a></div><div class="vp-nav-item hide-in-mobile"><a class="route-link auto-link" href="/Download/" aria-label="Download"><!---->Download<!----></a></div><div class="vp-nav-item hide-in-mobile"><div class="vp-dropdown-wrapper"><button type="button" class="vp-dropdown-title" aria-label="Community"><!--[--><!---->Community<!--]--><span class="arrow"></span><ul class="vp-dropdown"><li class="vp-dropdown-item"><a class="route-link auto-link" href="/Community/About-the-Community.html" aria-label="About the Community"><!---->About the Community<!----></a></li><li class="vp-dropdown-item"><a class="route-link auto-link" href="/Community/Development-Guide.html" aria-label="Development Guide"><!---->Development Guide<!----></a></li><li class="vp-dropdown-item"><a class="route-link auto-link" href="/Community/Community-Partners.html" aria-label="Community Partners"><!---->Community Partners<!----></a></li><li class="vp-dropdown-item"><a class="route-link auto-link" href="/Community/Communication-Channels.html" aria-label="Communication Channels"><!---->Communication Channels<!----></a></li><li class="vp-dropdown-item"><a class="route-link auto-link" href="/Community/Events-and-Reports.html" aria-label="Events and Reports"><!---->Events and Reports<!----></a></li><li class="vp-dropdown-item"><a class="route-link auto-link" href="/Community/Commiters.html" aria-label="Commiters"><!---->Commiters<!----></a></li></ul></button></div></div><div class="vp-nav-item hide-in-mobile"><div class="vp-dropdown-wrapper"><button type="button" class="vp-dropdown-title" aria-label="ASF"><!--[--><!---->ASF<!--]--><span class="arrow"></span><ul class="vp-dropdown"><li class="vp-dropdown-item"><a class="auto-link external-link" href="https://www.apache.org/" aria-label="Foundation" rel="noopener noreferrer" target="_blank"><!---->Foundation<!----></a></li><li class="vp-dropdown-item"><a class="auto-link external-link" href="https://www.apache.org/licenses/" aria-label="License" rel="noopener noreferrer" target="_blank"><!---->License<!----></a></li><li class="vp-dropdown-item"><a class="auto-link external-link" href="https://www.apache.org/security/" aria-label="Security" rel="noopener noreferrer" target="_blank"><!---->Security<!----></a></li><li class="vp-dropdown-item"><a class="auto-link external-link" href="https://www.apache.org/foundation/sponsorship.html" aria-label="Sponsorship" rel="noopener noreferrer" target="_blank"><!---->Sponsorship<!----></a></li><li class="vp-dropdown-item"><a class="auto-link external-link" href="https://www.apache.org/foundation/thanks.html" aria-label="Thanks" rel="noopener noreferrer" target="_blank"><!---->Thanks<!----></a></li><li class="vp-dropdown-item"><a class="auto-link external-link" href="https://www.apache.org/events/current-event" aria-label="Current Events" rel="noopener noreferrer" target="_blank"><!---->Current Events<!----></a></li><li class="vp-dropdown-item"><a class="auto-link external-link" href="https://privacy.apache.org/policies/privacy-policy-public.html" aria-label="Privacy" rel="noopener noreferrer" target="_blank"><!---->Privacy<!----></a></li></ul></button></div></div></nav><div class="vp-nav-item"><div class="vp-dropdown-wrapper"><button type="button" class="vp-dropdown-title" aria-label="Select language"><!--[--><svg xmlns="http://www.w3.org/2000/svg" class="icon i18n-icon" viewBox="0 0 1024 1024" fill="currentColor" aria-label="i18n icon" name="i18n" 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="vp-dropdown"><li class="vp-dropdown-item"><a class="route-link route-link-active auto-link" href="/UserGuide/latest/Basic-Concept/Cluster-data-partitioning.html" aria-label="English"><!---->English<!----></a></li><li class="vp-dropdown-item"><a class="route-link auto-link" href="/zh/UserGuide/latest/Basic-Concept/Cluster-data-partitioning.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" class="vp-color-mode-switch" id="color-mode-switch"><svg xmlns="http://www.w3.org/2000/svg" class="icon auto-icon" viewBox="0 0 1024 1024" fill="currentColor" aria-label="auto icon" name="auto" 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" name="dark" 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" name="light" 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" name="github" 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 User Guide (V1.3.0/1/2)</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">About IoTDB</span><span class="vp-arrow end"></span></button><!----></section></li><li><a class="route-link auto-link vp-sidebar-link" href="/UserGuide/latest/QuickStart/QuickStart_apache.html" aria-label="Quick Start"><!---->Quick Start<!----></a></li><li><section class="vp-sidebar-group"><button class="vp-sidebar-header clickable active" type="button"><!----><span class="vp-sidebar-title">Basic Concept</span><span class="vp-arrow down"></span></button><ul class="vp-sidebar-links"><li><a class="route-link auto-link vp-sidebar-link" href="/UserGuide/latest/Basic-Concept/Navigating_Time_Series_Data.html" aria-label="Navigating Time Series Data"><!---->Navigating Time Series Data<!----></a></li><li><a class="route-link auto-link vp-sidebar-link" href="/UserGuide/latest/Basic-Concept/Data-Model-and-Terminology.html" aria-label="Data Model"><!---->Data Model<!----></a></li><li><a class="route-link auto-link vp-sidebar-link" href="/UserGuide/latest/Basic-Concept/Data-Type.html" aria-label="Data Type"><!---->Data Type<!----></a></li><li><a class="route-link auto-link vp-sidebar-link" href="/UserGuide/latest/Basic-Concept/Encoding-and-Compression.html" aria-label="Encoding and Compression"><!---->Encoding and Compression<!----></a></li><li><a class="route-link route-link-active auto-link vp-sidebar-link active" href="/UserGuide/latest/Basic-Concept/Cluster-data-partitioning.html" aria-label="Data Partitioning & Load Balancing"><!---->Data Partitioning & Load Balancing<!----></a></li></ul></section></li><li><section class="vp-sidebar-group"><button class="vp-sidebar-header clickable" type="button"><!----><span class="vp-sidebar-title">Deployment & Maintenance</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">User Manual</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">Tools System</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">API</span><span class="vp-arrow end"></span></button><!----></section></li><li><section class="vp-sidebar-group"><button class="vp-sidebar-header clickable" type="button"><!----><span class="vp-sidebar-title">Ecosystem Integration</span><span class="vp-arrow end"></span></button><!----></section></li><li><section class="vp-sidebar-group"><button class="vp-sidebar-header clickable" type="button"><!----><span class="vp-sidebar-title">SQL Manual</span><span class="vp-arrow end"></span></button><!----></section></li><li><section class="vp-sidebar-group"><button class="vp-sidebar-header clickable" type="button"><!----><span class="vp-sidebar-title">FAQ</span><span class="vp-arrow end"></span></button><!----></section></li><li><section class="vp-sidebar-group"><button class="vp-sidebar-header clickable" type="button"><!----><span class="vp-sidebar-title">Reference</span><span class="vp-arrow end"></span></button><!----></section></li></ul><!----></aside><!--[--><!--[--><main id="main-content" class="vp-page"><!--[--><!----><!----><nav class="vp-breadcrumb disable"></nav><div class="vp-page-title"><h1><!---->Load Balance</h1><div class="page-info"><!----><!----><span class="page-date-info" aria-label="Writing Date"><svg xmlns="http://www.w3.org/2000/svg" class="icon calendar-icon" viewBox="0 0 1024 1024" fill="currentColor" aria-label="calendar icon" name="calendar"><path d="M716.4 110.137c0-18.753-14.72-33.473-33.472-33.473-18.753 0-33.473 14.72-33.473 33.473v33.473h66.993v-33.473zm-334.87 0c0-18.753-14.72-33.473-33.473-33.473s-33.52 14.72-33.52 33.473v33.473h66.993v-33.473zm468.81 33.52H716.4v100.465c0 18.753-14.72 33.473-33.472 33.473a33.145 33.145 0 01-33.473-33.473V143.657H381.53v100.465c0 18.753-14.72 33.473-33.473 33.473a33.145 33.145 0 01-33.473-33.473V143.657H180.6A134.314 134.314 0 0046.66 277.595v535.756A134.314 134.314 0 00180.6 947.289h669.74a134.36 134.36 0 00133.94-133.938V277.595a134.314 134.314 0 00-133.94-133.938zm33.473 267.877H147.126a33.145 33.145 0 01-33.473-33.473c0-18.752 14.72-33.473 33.473-33.473h736.687c18.752 0 33.472 14.72 33.472 33.473a33.145 33.145 0 01-33.472 33.473z"></path></svg><span><!----></span><meta property="datePublished" content="2023-08-14T08:04:43.000Z"></span><!----><span class="page-reading-time-info" aria-label="Reading Time"><svg xmlns="http://www.w3.org/2000/svg" class="icon timer-icon" viewBox="0 0 1024 1024" fill="currentColor" aria-label="timer icon" name="timer"><path d="M799.387 122.15c4.402-2.978 7.38-7.897 7.38-13.463v-1.165c0-8.933-7.38-16.312-16.312-16.312H256.33c-8.933 0-16.311 7.38-16.311 16.312v1.165c0 5.825 2.977 10.874 7.637 13.592 4.143 194.44 97.22 354.963 220.201 392.763-122.204 37.542-214.893 196.511-220.2 389.397-4.661 5.049-7.638 11.651-7.638 19.03v5.825h566.49v-5.825c0-7.379-2.849-13.981-7.509-18.9-5.049-193.016-97.867-351.985-220.2-389.527 123.24-37.67 216.446-198.453 220.588-392.892zM531.16 450.445v352.632c117.674 1.553 211.787 40.778 211.787 88.676H304.097c0-48.286 95.149-87.382 213.728-88.676V450.445c-93.077-3.107-167.901-81.297-167.901-177.093 0-8.803 6.99-15.793 15.793-15.793 8.803 0 15.794 6.99 15.794 15.793 0 80.261 63.69 145.635 142.01 145.635s142.011-65.374 142.011-145.635c0-8.803 6.99-15.793 15.794-15.793s15.793 6.99 15.793 15.793c0 95.019-73.789 172.82-165.96 177.093z"></path></svg><span>About 5 min</span><meta property="timeRequired" content="PT5M"></span><!----><!----></div><hr></div><div class="vp-toc-placeholder"><aside id="toc"><!----><div class="vp-toc-header">On This Page<button type="button" class="print-button" title="Print"><svg xmlns="http://www.w3.org/2000/svg" class="icon print-icon" viewBox="0 0 1024 1024" fill="currentColor" aria-label="print icon" name="print"><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="#partitioning-strategy-partition-allocation">Partitioning Strategy & Partition Allocation</a></li><li><ul class="vp-toc-list"><!--[--><li class="vp-toc-item"><a class="route-link vp-toc-link level3" href="#partitioning-strategy">Partitioning Strategy</a></li><!----><!--]--><!--[--><li class="vp-toc-item"><a class="route-link vp-toc-link level3" href="#partition-allocation">Partition Allocation</a></li><!----><!--]--></ul></li><!--]--><!--[--><li class="vp-toc-item"><a class="route-link vp-toc-link level2" href="#balance-strategy">Balance Strategy</a></li><li><ul class="vp-toc-list"><!--[--><li class="vp-toc-item"><a class="route-link vp-toc-link level3" href="#storage-load-balance">Storage Load Balance</a></li><!----><!--]--><!--[--><li class="vp-toc-item"><a class="route-link vp-toc-link level3" href="#computing-load-balance">Computing Load Balance</a></li><!----><!--]--></ul></li><!--]--><!--[--><li class="vp-toc-item"><a class="route-link vp-toc-link level2" href="#source-code">Source Code</a></li><!----><!--]--></ul><div class="vp-toc-marker" style="top:-1.7rem;"></div></div><!----></aside></div><!----><div class="theme-hope-content"><h1 id="load-balance" tabindex="-1"><a class="header-anchor" href="#load-balance"><span>Load Balance</span></a></h1><p>This document introduces the partitioning strategies and load balance strategies in IoTDB. According to the characteristics of time series data, IoTDB partitions them by series and time dimensions. Combining a series partition with a time partition creates a partition, the unit of division. To enhance throughput and reduce management costs, these partitions are evenly allocated to RegionGroups, which serve as the unit of replication. The RegionGroup's Regions then determine the storage location, with the leader Region managing the primary load. During this process, the Region placement strategy determines which nodes will host the replicas, while the leader selection strategy designates which Region will act as the leader.</p><h2 id="partitioning-strategy-partition-allocation" tabindex="-1"><a class="header-anchor" href="#partitioning-strategy-partition-allocation"><span>Partitioning Strategy & Partition Allocation</span></a></h2><p>IoTDB implements tailored partitioning algorithms for time series data. Building on this foundation, the partition information cached on both ConfigNodes and DataNodes is not only manageable in size but also clearly differentiated between hot and cold. Subsequently, balanced partitions are evenly allocated across the cluster's RegionGroups to achieve storage balance.</p><h3 id="partitioning-strategy" tabindex="-1"><a class="header-anchor" href="#partitioning-strategy"><span>Partitioning Strategy</span></a></h3><p>IoTDB maps each sensor in the production environment to a time series. The time series are then partitioned using the series partitioning algorithm to manage their schema, and combined with the time partitioning algorithm to manage their data. The following figure illustrates how IoTDB partitions time series data.</p><img style="width:100%;max-width:800px;max-height:600px;margin-left:auto;margin-right:auto;display:block;" src="https://alioss.timecho.com/docs/img/partition_table_en.png?raw=true"><h4 id="partitioning-algorithm" tabindex="-1"><a class="header-anchor" href="#partitioning-algorithm"><span>Partitioning Algorithm</span></a></h4><p>Because numerous devices and sensors are commonly deployed in production environments, IoTDB employs a series partitioning algorithm to ensure the size of partition information is manageable. Since the generated time series associated with timestamps, IoTDB uses a time partioning algorithm to clearly distinguish between hot and cold partitions.</p><h5 id="series-partitioning-algorithm" tabindex="-1"><a class="header-anchor" href="#series-partitioning-algorithm"><span>Series Partitioning Algorithm</span></a></h5><p>By default, IoTDB limits the number of series partitions to 1000 and configures the series partitioning algorithm to use a hash partitioning algorithm. This leads to the following outcomes:</p><ul><li>Since the number of series partitions is a fixed constant, the mapping between series and series partitions remains stable. As a result, IoTDB does not require frequent data migrations.</li><li>The load across series partitions is relatively balanced because the number of series partitions is much smaller than the number of sensors deployed in the production environment.</li></ul><p>Furthermore, if a more accurate estimate of the actual load in the production environment is available, the series partitioning algorithm can be configured to use a customized hash partitioning or a list partitioning to achieve a more uniform load distribution across all series partitions.</p><h5 id="time-partitioning-algorithm" tabindex="-1"><a class="header-anchor" href="#time-partitioning-algorithm"><span>Time Partitioning Algorithm</span></a></h5><p>The time partitioning algorithm converts a given timestamp to the corresponding time partition by</p><p class="katex-block"><span class="katex-display"><span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML" display="block"><semantics><mrow><mrow><mo fence="true">⌊</mo><mfrac><mrow><mtext>Timestamp</mtext><mo>−</mo><mtext>StartTimestamp</mtext></mrow><mtext>TimePartitionInterval</mtext></mfrac><mo fence="true">⌋</mo></mrow><mi mathvariant="normal">.</mi></mrow><annotation encoding="application/x-tex"> \left\lfloor\frac{\text{Timestamp}-\text{StartTimestamp}}{\text{TimePartitionInterval}}\right\rfloor. </annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:2.4em;vertical-align:-0.95em;"></span><span class="minner"><span class="mopen delimcenter" style="top:0em;"><span class="delimsizing size3">⌊</span></span><span class="mord"><span class="mopen nulldelimiter"></span><span class="mfrac"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:1.3603em;"><span style="top:-2.314em;"><span class="pstrut" style="height:3em;"></span><span class="mord"><span class="mord text"><span class="mord">TimePartitionInterval</span></span></span></span><span style="top:-3.23em;"><span class="pstrut" style="height:3em;"></span><span class="frac-line" style="border-bottom-width:0.04em;"></span></span><span style="top:-3.677em;"><span class="pstrut" style="height:3em;"></span><span class="mord"><span class="mord text"><span class="mord">Timestamp</span></span><span class="mspace" style="margin-right:0.2222em;"></span><span class="mbin">−</span><span class="mspace" style="margin-right:0.2222em;"></span><span class="mord text"><span class="mord">StartTimestamp</span></span></span></span></span><span class="vlist-s"></span></span><span class="vlist-r"><span class="vlist" style="height:0.686em;"><span></span></span></span></span></span><span class="mclose nulldelimiter"></span></span><span class="mclose delimcenter" style="top:0em;"><span class="delimsizing size3">⌋</span></span></span><span class="mspace" style="margin-right:0.1667em;"></span><span class="mord">.</span></span></span></span></span></p><p>In this equation, both <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mtext>StartTimestamp</mtext></mrow><annotation encoding="application/x-tex">\text{StartTimestamp}</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.8778em;vertical-align:-0.1944em;"></span><span class="mord text"><span class="mord">StartTimestamp</span></span></span></span></span> and <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mtext>TimePartitionInterval</mtext></mrow><annotation encoding="application/x-tex">\text{TimePartitionInterval}</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.6944em;"></span><span class="mord text"><span class="mord">TimePartitionInterval</span></span></span></span></span> are configurable parameters to accommodate various production environments. The <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mtext>StartTimestamp</mtext></mrow><annotation encoding="application/x-tex">\text{StartTimestamp}</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.8778em;vertical-align:-0.1944em;"></span><span class="mord text"><span class="mord">StartTimestamp</span></span></span></span></span> represents the starting time of the first time partition, while the <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mtext>TimePartitionInterval</mtext></mrow><annotation encoding="application/x-tex">\text{TimePartitionInterval}</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.6944em;"></span><span class="mord text"><span class="mord">TimePartitionInterval</span></span></span></span></span> defines the duration of each time partition. By default, the <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mtext>TimePartitionInterval</mtext></mrow><annotation encoding="application/x-tex">\text{TimePartitionInterval}</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.6944em;"></span><span class="mord text"><span class="mord">TimePartitionInterval</span></span></span></span></span> is set to one day.</p><h4 id="schema-partitioning" tabindex="-1"><a class="header-anchor" href="#schema-partitioning"><span>Schema Partitioning</span></a></h4><p>Since the series partitioning algorithm evenly partitions the time series, each series partition corresponds to a schema partition. These schema partitions are then evenly allocated across the SchemaRegionGroups to achieve a balanced schema distribution.</p><h4 id="data-partitioning" tabindex="-1"><a class="header-anchor" href="#data-partitioning"><span>Data Partitioning</span></a></h4><p>Combining a series partition with a time partition creates a data partition. Since the series partitioning algorithm evenly partitions the time series, the load of data partitions within a specified time partition remains balanced. These data partitions are then evenly allocated across the DataRegionGroups to achieve balanced data distribution.</p><h3 id="partition-allocation" tabindex="-1"><a class="header-anchor" href="#partition-allocation"><span>Partition Allocation</span></a></h3><p>IoTDB uses RegionGroups to enable elastic storage of time series, with the number of RegionGroups in the cluster determined by the total resources available across all DataNodes. Since the number of RegionGroups is dynamic, IoTDB can easily scale out. Both the SchemaRegionGroup and DataRegionGroup follow the same partition allocation algorithm, which evenly splits all series partitions. The following figure demonstrates the partition allocation process, where the dynamic RegionGroups match the variously expending time series and cluster.</p><img style="width:100%;max-width:800px;max-height:600px;margin-left:auto;margin-right:auto;display:block;" src="https://alioss.timecho.com/docs/img/partition_allocation_en.png?raw=true"><h4 id="regiongroup-expansion" tabindex="-1"><a class="header-anchor" href="#regiongroup-expansion"><span>RegionGroup Expansion</span></a></h4><p>The number of RegionGroups is given by</p><p class="katex-block"><span class="katex-display"><span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML" display="block"><semantics><mrow><mtext>RegionGroupNumber</mtext><mo>=</mo><mrow><mo fence="true">⌊</mo><mfrac><mrow><munderover><mo>∑</mo><mrow><mi>i</mi><mo>=</mo><mn>1</mn></mrow><mrow><mi>D</mi><mi>a</mi><mi>t</mi><mi>a</mi><mi>N</mi><mi>o</mi><mi>d</mi><mi>e</mi><mi>N</mi><mi>u</mi><mi>m</mi><mi>b</mi><mi>e</mi><mi>r</mi></mrow></munderover><msub><mtext>RegionNumber</mtext><mi>i</mi></msub></mrow><mtext>ReplicationFactor</mtext></mfrac><mo fence="true">⌋</mo></mrow><mi mathvariant="normal">.</mi></mrow><annotation encoding="application/x-tex"> \text{RegionGroupNumber}=\left\lfloor\frac{\sum_{i=1}^{DataNodeNumber}\text{RegionNumber}_i}{\text{ReplicationFactor}}\right\rfloor. </annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.8889em;vertical-align:-0.1944em;"></span><span class="mord text"><span class="mord">RegionGroupNumber</span></span><span class="mspace" style="margin-right:0.2778em;"></span><span class="mrel">=</span><span class="mspace" style="margin-right:0.2778em;"></span></span><span class="base"><span class="strut" style="height:3em;vertical-align:-1.25em;"></span><span class="minner"><span class="mopen delimcenter" style="top:0em;"><span class="delimsizing size4">⌊</span></span><span class="mord"><span class="mopen nulldelimiter"></span><span class="mfrac"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:1.6787em;"><span style="top:-2.314em;"><span class="pstrut" style="height:3em;"></span><span class="mord"><span class="mord text"><span class="mord">ReplicationFactor</span></span></span></span><span style="top:-3.23em;"><span class="pstrut" style="height:3em;"></span><span class="frac-line" style="border-bottom-width:0.04em;"></span></span><span style="top:-3.6897em;"><span class="pstrut" style="height:3em;"></span><span class="mord"><span class="mop"><span class="mop op-symbol small-op" style="position:relative;top:0em;">∑</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.989em;"><span style="top:-2.4003em;margin-left:0em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight"><span class="mord mathnormal mtight">i</span><span class="mrel mtight">=</span><span class="mord mtight">1</span></span></span></span><span style="top:-3.2029em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight"><span class="mord mathnormal mtight" style="margin-right:0.02778em;">D</span><span class="mord mathnormal mtight">a</span><span class="mord mathnormal mtight">t</span><span class="mord mathnormal mtight">a</span><span class="mord mathnormal mtight" style="margin-right:0.10903em;">N</span><span class="mord mathnormal mtight">o</span><span class="mord mathnormal mtight">d</span><span class="mord mathnormal mtight">e</span><span class="mord mathnormal mtight" style="margin-right:0.10903em;">N</span><span class="mord mathnormal mtight">u</span><span class="mord mathnormal mtight">mb</span><span class="mord mathnormal mtight" style="margin-right:0.02778em;">er</span></span></span></span></span><span class="vlist-s"></span></span><span class="vlist-r"><span class="vlist" style="height:0.2997em;"><span></span></span></span></span></span></span><span class="mspace" style="margin-right:0.1667em;"></span><span class="mord"><span class="mord text"><span class="mord">RegionNumber</span></span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.2175em;"><span style="top:-2.4559em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">i</span></span></span></span><span class="vlist-s"></span></span><span class="vlist-r"><span class="vlist" style="height:0.2441em;"><span></span></span></span></span></span></span></span></span></span><span class="vlist-s"></span></span><span class="vlist-r"><span class="vlist" style="height:0.8804em;"><span></span></span></span></span></span><span class="mclose nulldelimiter"></span></span><span class="mclose delimcenter" style="top:0em;"><span class="delimsizing size4">⌋</span></span></span><span class="mspace" style="margin-right:0.1667em;"></span><span class="mord">.</span></span></span></span></span></p><p>In this equation, <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mtext>RegionNumber</mtext><mi>i</mi></msub></mrow><annotation encoding="application/x-tex">\text{RegionNumber}_i</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.9386em;vertical-align:-0.2441em;"></span><span class="mord"><span class="mord text"><span class="mord">RegionNumber</span></span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.2175em;"><span style="top:-2.4559em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">i</span></span></span></span><span class="vlist-s"></span></span><span class="vlist-r"><span class="vlist" style="height:0.2441em;"><span></span></span></span></span></span></span></span></span></span> represents the number of Regions expected to be hosted on the <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>i</mi></mrow><annotation encoding="application/x-tex">i</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.6595em;"></span><span class="mord mathnormal">i</span></span></span></span>-th DataNode, while <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mtext>ReplicationFactor</mtext></mrow><annotation encoding="application/x-tex">\text{ReplicationFactor}</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.8889em;vertical-align:-0.1944em;"></span><span class="mord text"><span class="mord">ReplicationFactor</span></span></span></span></span> denotes the number of Regions within each RegionGroup. Both <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mtext>RegionNumber</mtext><mi>i</mi></msub></mrow><annotation encoding="application/x-tex">\text{RegionNumber}_i</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.9386em;vertical-align:-0.2441em;"></span><span class="mord"><span class="mord text"><span class="mord">RegionNumber</span></span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.2175em;"><span style="top:-2.4559em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">i</span></span></span></span><span class="vlist-s"></span></span><span class="vlist-r"><span class="vlist" style="height:0.2441em;"><span></span></span></span></span></span></span></span></span></span> and <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mtext>ReplicationFactor</mtext></mrow><annotation encoding="application/x-tex">\text{ReplicationFactor}</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.8889em;vertical-align:-0.1944em;"></span><span class="mord text"><span class="mord">ReplicationFactor</span></span></span></span></span> are configurable parameters. The <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mtext>RegionNumber</mtext><mi>i</mi></msub></mrow><annotation encoding="application/x-tex">\text{RegionNumber}_i</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.9386em;vertical-align:-0.2441em;"></span><span class="mord"><span class="mord text"><span class="mord">RegionNumber</span></span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.2175em;"><span style="top:-2.4559em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">i</span></span></span></span><span class="vlist-s"></span></span><span class="vlist-r"><span class="vlist" style="height:0.2441em;"><span></span></span></span></span></span></span></span></span></span> can be determined by the available hardware resources---such as CPU cores, memory sizes, etc.---on the <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>i</mi></mrow><annotation encoding="application/x-tex">i</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.6595em;"></span><span class="mord mathnormal">i</span></span></span></span>-th DataNode to accommodate different physical servers. The <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mtext>ReplicationFactor</mtext></mrow><annotation encoding="application/x-tex">\text{ReplicationFactor}</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.8889em;vertical-align:-0.1944em;"></span><span class="mord text"><span class="mord">ReplicationFactor</span></span></span></span></span> can be adjusted to ensure diverse levels of fault tolerance.</p><h4 id="allocation-algorithm" tabindex="-1"><a class="header-anchor" href="#allocation-algorithm"><span>Allocation Algorithm</span></a></h4><p>Both the SchemaRegionGroup and the DataRegionGroup follow the same allocation algorithm--splitting all series partitions evenly. As a result, each SchemaRegionGroup holds the same number of schema partitions, ensuring balanced schema storage. Similarly, for each time partition, each DataRegionGroup acquires the data partitions corresponding to the series partitions it holds. Consequently, the data partitions within a time partition are evenly distributed across all DataRegionGroups, ensuring balanced data storage in each time partition.</p><p>Notably, IoTDB effectively leverages the characteristics of time series data. When the TTL (Time to Live) is configured, IoTDB enables migration-free elastic storage for time series data. This feature facilitates cluster expansion while minimizing the impact on online operations. The figures above illustrate an instance of this feature: newborn data partitions are evenly allocated to each DataRegion, and expired data are automatically archived. As a result, the cluster's storage will eventually remain balanced.</p><h2 id="balance-strategy" tabindex="-1"><a class="header-anchor" href="#balance-strategy"><span>Balance Strategy</span></a></h2><p>To enhance the cluster's availability and performance, IoTDB employs sophisticated storage load and computing load balance algorithms.</p><h3 id="storage-load-balance" tabindex="-1"><a class="header-anchor" href="#storage-load-balance"><span>Storage Load Balance</span></a></h3><p>The number of Regions held by a DataNode reflects its storage load. If the difference in the number of Regions across DataNodes is relatively large, the DataNode with more Regions is likely to become a storage bottleneck. Although a straightforward Round Robin placement algorithm can achieve storage balance by ensuring that each DataNode hosts an equal number of Regions, it compromises the cluster's fault tolerance, as illustrated below:</p><img style="width:100%;max-width:800px;max-height:600px;margin-left:auto;margin-right:auto;display:block;" src="https://alioss.timecho.com/docs/img/placement_en.png?raw=true"><ul><li>Assume the cluster has 4 DataNodes, 4 RegionGroups and a replication factor of 2.</li><li>Place RegionGroup <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>r</mi><mn>1</mn></msub></mrow><annotation encoding="application/x-tex">r_1</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.5806em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.3011em;"><span style="top:-2.55em;margin-left:-0.0278em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight">1</span></span></span></span><span class="vlist-s"></span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span>'s 2 Regions on DataNodes <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>n</mi><mn>1</mn></msub></mrow><annotation encoding="application/x-tex">n_1</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.5806em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal">n</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.3011em;"><span style="top:-2.55em;margin-left:0em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight">1</span></span></span></span><span class="vlist-s"></span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span> and <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>n</mi><mn>2</mn></msub></mrow><annotation encoding="application/x-tex">n_2</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.5806em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal">n</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.3011em;"><span style="top:-2.55em;margin-left:0em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight">2</span></span></span></span><span class="vlist-s"></span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span>.</li><li>Place RegionGroup <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>r</mi><mn>2</mn></msub></mrow><annotation encoding="application/x-tex">r_2</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.5806em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.3011em;"><span style="top:-2.55em;margin-left:-0.0278em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight">2</span></span></span></span><span class="vlist-s"></span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span>'s 2 Regions on DataNodes <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>n</mi><mn>3</mn></msub></mrow><annotation encoding="application/x-tex">n_3</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.5806em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal">n</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.3011em;"><span style="top:-2.55em;margin-left:0em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight">3</span></span></span></span><span class="vlist-s"></span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span> and <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>n</mi><mn>4</mn></msub></mrow><annotation encoding="application/x-tex">n_4</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.5806em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal">n</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.3011em;"><span style="top:-2.55em;margin-left:0em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight">4</span></span></span></span><span class="vlist-s"></span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span>.</li><li>Place RegionGroup <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>r</mi><mn>3</mn></msub></mrow><annotation encoding="application/x-tex">r_3</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.5806em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.3011em;"><span style="top:-2.55em;margin-left:-0.0278em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight">3</span></span></span></span><span class="vlist-s"></span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span>'s 2 Regions on DataNodes <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>n</mi><mn>1</mn></msub></mrow><annotation encoding="application/x-tex">n_1</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.5806em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal">n</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.3011em;"><span style="top:-2.55em;margin-left:0em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight">1</span></span></span></span><span class="vlist-s"></span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span> and <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>n</mi><mn>3</mn></msub></mrow><annotation encoding="application/x-tex">n_3</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.5806em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal">n</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.3011em;"><span style="top:-2.55em;margin-left:0em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight">3</span></span></span></span><span class="vlist-s"></span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span>.</li><li>Place RegionGroup <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>r</mi><mn>4</mn></msub></mrow><annotation encoding="application/x-tex">r_4</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.5806em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.3011em;"><span style="top:-2.55em;margin-left:-0.0278em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight">4</span></span></span></span><span class="vlist-s"></span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span>'s 2 Regions on DataNodes <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>n</mi><mn>2</mn></msub></mrow><annotation encoding="application/x-tex">n_2</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.5806em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal">n</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.3011em;"><span style="top:-2.55em;margin-left:0em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight">2</span></span></span></span><span class="vlist-s"></span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span> and <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>n</mi><mn>4</mn></msub></mrow><annotation encoding="application/x-tex">n_4</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.5806em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal">n</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.3011em;"><span style="top:-2.55em;margin-left:0em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight">4</span></span></span></span><span class="vlist-s"></span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span>.</li></ul><p>In this scenario, if DataNode <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>n</mi><mn>2</mn></msub></mrow><annotation encoding="application/x-tex">n_2</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.5806em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal">n</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.3011em;"><span style="top:-2.55em;margin-left:0em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight">2</span></span></span></span><span class="vlist-s"></span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span> fails, the load previously handled by DataNode <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>n</mi><mn>2</mn></msub></mrow><annotation encoding="application/x-tex">n_2</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.5806em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal">n</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.3011em;"><span style="top:-2.55em;margin-left:0em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight">2</span></span></span></span><span class="vlist-s"></span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span> would be transferred solely to DataNode <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>n</mi><mn>1</mn></msub></mrow><annotation encoding="application/x-tex">n_1</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.5806em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal">n</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.3011em;"><span style="top:-2.55em;margin-left:0em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight">1</span></span></span></span><span class="vlist-s"></span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span>, potentially overloading it.</p><p>To address this issue, IoTDB employs a Region placement algorithm that not only evenly distributes Regions across all DataNodes but also ensures that each DataNode can offload its storage to sufficient other DataNodes in the event of a failure. As a result, the cluster achieves balanced storage distribution and a high level of fault tolerance, ensuring its availability.</p><h3 id="computing-load-balance" tabindex="-1"><a class="header-anchor" href="#computing-load-balance"><span>Computing Load Balance</span></a></h3><p>The number of leader Regions held by a DataNode reflects its Computing load. If the difference in the number of leaders across DataNodes is relatively large, the DataNode with more leaders is likely to become a Computing bottleneck. If the leader selection process is conducted using a transparent Greedy algorithm, the result may be an unbalanced leader distribution when the Regions are fault-tolerantly placed, as demonstrated below:</p><img style="width:100%;max-width:800px;max-height:600px;margin-left:auto;margin-right:auto;display:block;" src="https://alioss.timecho.com/docs/img/selection_en.png?raw=true"><ul><li>Assume the cluster has 4 DataNodes, 4 RegionGroups and a replication factor of 2.</li><li>Select RegionGroup <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>r</mi><mn>5</mn></msub></mrow><annotation encoding="application/x-tex">r_5</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.5806em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.3011em;"><span style="top:-2.55em;margin-left:-0.0278em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight">5</span></span></span></span><span class="vlist-s"></span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span>'s Region on DataNode <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>n</mi><mn>5</mn></msub></mrow><annotation encoding="application/x-tex">n_5</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.5806em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal">n</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.3011em;"><span style="top:-2.55em;margin-left:0em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight">5</span></span></span></span><span class="vlist-s"></span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span> as the leader.</li><li>Select RegionGroup <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>r</mi><mn>6</mn></msub></mrow><annotation encoding="application/x-tex">r_6</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.5806em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.3011em;"><span style="top:-2.55em;margin-left:-0.0278em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight">6</span></span></span></span><span class="vlist-s"></span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span>'s Region on DataNode <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>n</mi><mn>7</mn></msub></mrow><annotation encoding="application/x-tex">n_7</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.5806em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal">n</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.3011em;"><span style="top:-2.55em;margin-left:0em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight">7</span></span></span></span><span class="vlist-s"></span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span> as the leader.</li><li>Select RegionGroup <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>r</mi><mn>7</mn></msub></mrow><annotation encoding="application/x-tex">r_7</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.5806em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.3011em;"><span style="top:-2.55em;margin-left:-0.0278em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight">7</span></span></span></span><span class="vlist-s"></span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span>'s Region on DataNode <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>n</mi><mn>7</mn></msub></mrow><annotation encoding="application/x-tex">n_7</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.5806em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal">n</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.3011em;"><span style="top:-2.55em;margin-left:0em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight">7</span></span></span></span><span class="vlist-s"></span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span> as the leader.</li><li>Select RegionGroup <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>r</mi><mn>8</mn></msub></mrow><annotation encoding="application/x-tex">r_8</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.5806em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.3011em;"><span style="top:-2.55em;margin-left:-0.0278em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight">8</span></span></span></span><span class="vlist-s"></span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span>'s Region on DataNode <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>n</mi><mn>8</mn></msub></mrow><annotation encoding="application/x-tex">n_8</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.5806em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal">n</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.3011em;"><span style="top:-2.55em;margin-left:0em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight">8</span></span></span></span><span class="vlist-s"></span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span> as the leader.</li></ul><p>Please note that all the above steps strictly follow the Greedy algorithm. However, by Step 3, selecting the leader of RegionGroup <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>r</mi><mn>7</mn></msub></mrow><annotation encoding="application/x-tex">r_7</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.5806em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.3011em;"><span style="top:-2.55em;margin-left:-0.0278em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight">7</span></span></span></span><span class="vlist-s"></span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span> on either DataNode <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>n</mi><mn>5</mn></msub></mrow><annotation encoding="application/x-tex">n_5</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.5806em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal">n</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.3011em;"><span style="top:-2.55em;margin-left:0em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight">5</span></span></span></span><span class="vlist-s"></span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span> or <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>n</mi><mn>7</mn></msub></mrow><annotation encoding="application/x-tex">n_7</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.5806em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal">n</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.3011em;"><span style="top:-2.55em;margin-left:0em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight">7</span></span></span></span><span class="vlist-s"></span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span> results in an unbalanced leader distribution. The rationale is that each greedy step lacks a global perspective, leading to a locally optimal solution.</p><p>To address this issue, IoTDB employs a leader selection algorithm that can consistently balance the cluster's leader distribution. Consequently, the cluster achieves balanced Computing load distribution, ensuring its performance.</p><h2 id="source-code" tabindex="-1"><a class="header-anchor" href="#source-code"><span>Source Code</span></a></h2><ul><li><a href="https://github.com/apache/iotdb/tree/master/iotdb-core/node-commons/src/main/java/org/apache/iotdb/commons/partition" target="_blank" rel="noopener noreferrer">Data Partitioning</a></li><li><a href="https://github.com/apache/iotdb/tree/master/iotdb-core/confignode/src/main/java/org/apache/iotdb/confignode/manager/load/balancer/partition" target="_blank" rel="noopener noreferrer">Partition Allocation</a></li><li><a href="https://github.com/apache/iotdb/tree/master/iotdb-core/confignode/src/main/java/org/apache/iotdb/confignode/manager/load/balancer/region" target="_blank" rel="noopener noreferrer">Region Placement</a></li><li><a href="https://github.com/apache/iotdb/tree/master/iotdb-core/confignode/src/main/java/org/apache/iotdb/confignode/manager/load/balancer/router/leader" target="_blank" rel="noopener noreferrer">Leader Selection</a></li></ul></div><!----><footer class="vp-page-meta"><div class="vp-meta-item edit-link"><a class="auto-link external-link vp-meta-label" href="https://github.com/apache/iotdb-docs/edit/main/src/UserGuide/latest/Basic-Concept/Cluster-data-partitioning.md" aria-label="Found Error? Edit this page on GitHub" rel="noopener noreferrer" target="_blank"><!--[--><svg xmlns="http://www.w3.org/2000/svg" class="icon edit-icon" viewBox="0 0 1024 1024" fill="currentColor" aria-label="edit icon" name="edit"><path d="M430.818 653.65a60.46 60.46 0 0 1-50.96-93.281l71.69-114.012 7.773-10.365L816.038 80.138A60.46 60.46 0 0 1 859.225 62a60.46 60.46 0 0 1 43.186 18.138l43.186 43.186a60.46 60.46 0 0 1 0 86.373L588.879 565.55l-8.637 8.637-117.466 68.234a60.46 60.46 0 0 1-31.958 11.229z"></path><path d="M728.802 962H252.891A190.883 190.883 0 0 1 62.008 771.98V296.934a190.883 190.883 0 0 1 190.883-192.61h267.754a60.46 60.46 0 0 1 0 120.92H252.891a69.962 69.962 0 0 0-69.098 69.099V771.98a69.962 69.962 0 0 0 69.098 69.098h475.911A69.962 69.962 0 0 0 797.9 771.98V503.363a60.46 60.46 0 1 1 120.922 0V771.98A190.883 190.883 0 0 1 728.802 962z"></path></svg><!--]-->Found Error? Edit this page on GitHub<!----></a></div><div class="vp-meta-item git-info"><div class="update-time"><span class="vp-meta-label">Last update: </span><!----></div><!----></div></footer><nav class="vp-page-nav"><a class="route-link auto-link prev" href="/UserGuide/latest/Basic-Concept/Encoding-and-Compression.html" aria-label="Encoding and Compression"><div class="hint"><span class="arrow start"></span>Prev</div><div class="link"><!---->Encoding and Compression</div></a><!----></nav><!----><!----><!--]--></main><!--]--><!--]--><footer style="padding-bottom:2rem;"><span id="doc-version" style="display:none;">latest</span><p style="text-align:center;color:#909399;font-size:12px;margin:0 30px;">Copyright © 2024 The Apache Software Foundation.<br> Apache IoTDB, IoTDB, Apache, the Apache feather logo, and the Apache IoTDB project logo are either registered trademarks or trademarks of The Apache Software Foundation in all countries</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-BRi6R9vN.js" defer></script> |
| </body> |
| </html> |
