(window.webpackJsonp=window.webpackJsonp||[]).push([[385],{953:function(t,e,v){"use strict";v.r(e);var _=v(69),a=Object(_.a)({},(function(){var t=this,e=t.$createElement,v=t._self._c||e;return v("ContentSlotsDistributor",{attrs:{"slot-key":t.$parent.slotKey}},[v("h1",{attrs:{id:"数据模式"}},[v("a",{staticClass:"header-anchor",attrs:{href:"#数据模式"}},[t._v("#")]),t._v(" 数据模式")]),t._v(" "),v("h2",{attrs:{id:"数据模型"}},[v("a",{staticClass:"header-anchor",attrs:{href:"#数据模型"}},[t._v("#")]),t._v(" 数据模型")]),t._v(" "),v("p",[t._v("本节，我们以电力场景为例，说明如何在IoTDB中创建一个正确的数据模型。")]),t._v(" "),v("p",[t._v("根据属性层级，属性涵盖范围以及数据之间的从属关系，我们可将其数据模型表示为如下图所示的属性层级组织结构，即电力集团层-电厂层-设备层-传感器层。其中ROOT为根节点，传感器层的每一个节点为叶子节点。IoTDB的语法规定，ROOT节点到叶子节点的路径以“.”连接，以此完整路径命名IoTDB中的一个时间序列。例如，下图最左侧路径对应的时间序列名称为"),v("code",[t._v("ROOT.ln.wf01.wt01.status")]),t._v("。")]),t._v(" "),v("img",{staticStyle:{width:"100%","max-width":"800px","max-height":"600px","margin-left":"auto","margin-right":"auto",display:"block"},attrs:{src:"https://user-images.githubusercontent.com/13203019/51577327-7aa50780-1ef4-11e9-9d75-cadabb62444e.jpg"}}),t._v(" "),v("p",[v("strong",[t._v("属性层级组织结构")])]),t._v(" "),v("p",[t._v("得到时间序列的名称之后，我们需要根据数据的实际场景和规模设置存储组。由于在本文所述场景中，每次到达的数据通常以集团为单位（即数据可能为跨电场、跨设备的），为了写入数据时避免频繁切换IO降低系统速度，且满足用户以集团为单位进行物理隔离数据的要求，我们将存储组设置在集团层。")]),t._v(" "),v("p",[t._v("根据模型结构，IoTDB中涉及如下基本概念：")]),t._v(" "),v("ul",[v("li",[t._v("设备")])]),t._v(" "),v("p",[t._v("设备指的是在实际场景中拥有传感器的装置。在IoTDB当中，所有的传感器都应有其对应的归属的设备。")]),t._v(" "),v("ul",[v("li",[t._v("传感器")])]),t._v(" "),v("p",[t._v("传感器是指在实际场景中的一种检测装置，它能感受到被测量的信息，并能将感受到的信息按一定规律变换成为电信号或其他所需形式的信息输出并发送给IoTDB。在IoTDB当中，存储的所有的数据及路径，都是以传感器为单位进行组织。")]),t._v(" "),v("ul",[v("li",[t._v("存储组")])]),t._v(" "),v("p",[t._v("用户可以将任意前缀路径设置成存储组。如有4条时间序列"),v("code",[t._v("root.vehicle.d1.s1")]),t._v(", 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"),v("p",[t._v("一个存储组设定后，其对应的前缀路径的所有父层级与子层级也不允许再设置存储组（如，"),v("code",[t._v("root.ln")]),t._v("设置存储组后，root层级与"),v("code",[t._v("root.ln.wf01")]),t._v("不允许被设置为存储组）。")]),t._v(" "),v("p",[t._v("存储组节点名只支持中英文字符、数字和下划线的组合。例如"),v("code",[t._v("root.存储组_1")]),t._v(" 。")]),t._v(" "),v("ul",[v("li",[t._v("路径")])]),t._v(" "),v("p",[t._v("在IoTDB中，路径是指符合以下约束的表达式：")]),t._v(" "),v("div",{staticClass:"language- line-numbers-mode"},[v("pre",{pre:!0,attrs:{class:"language-text"}},[v("code",[t._v("path: LayerName (DOT LayerName)+\nLayerName: Identifier | STAR\n")])]),t._v(" "),v("div",{staticClass:"line-numbers-wrapper"},[v("span",{staticClass:"line-number"},[t._v("1")]),v("br"),v("span",{staticClass:"line-number"},[t._v("2")]),v("br")])]),v("p",[t._v("其中STAR为“*”，DOT为“.”。")]),t._v(" "),v("p",[t._v("我们称一个路径中在两个“.”中间的部分叫做一个层级，则"),v("code",[t._v("root.a.b.c")]),t._v("为一个层级为4的路径。")]),t._v(" "),v("p",[t._v("值得说明的是，在路径中，root为一个保留字符，它只允许出现在下文提到的时间序列的开头，若其他层级出现root，则无法解析，提示报错。")]),t._v(" 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