assets/Overview.html-27db0e41.js

import{_ as l,C as s,O as p,P as h,ah as r,Q as t,U as d,ai as e,ae as a,aW as n}from"./framework-62ad666a.js";const i={},u=t("h1",{id:"运算符和函数",tabindex:"-1"},[t("a",{class:"header-anchor",href:"#运算符和函数","aria-hidden":"true"},"#"),d(" 运算符和函数")],-1),T=t("p",null,[d("可以使用 "),t("code",null,"SHOW FUNCTIONS"),d(" 显示所有可用函数的列表，包括内置函数和自定义函数。")],-1),O=n('<h2 id="运算符列表" tabindex="-1"><a class="header-anchor" href="#运算符列表" aria-hidden="true">#</a> 运算符列表</h2><h3 id="算数运算符" tabindex="-1"><a class="header-anchor" href="#算数运算符" aria-hidden="true">#</a> 算数运算符</h3><table><thead><tr><th>运算符</th><th>含义</th></tr></thead><tbody><tr><td><code>+</code></td><td>取正（单目）</td></tr><tr><td><code>-</code></td><td>取负（单目）</td></tr><tr><td><code>*</code></td><td>乘</td></tr><tr><td><code>/</code></td><td>除</td></tr><tr><td><code>%</code></td><td>取余</td></tr><tr><td><code>+</code></td><td>加</td></tr><tr><td><code>-</code></td><td>减</td></tr></tbody></table>',3),E=n('<h3 id="比较运算符" tabindex="-1"><a class="header-anchor" href="#比较运算符" aria-hidden="true">#</a> 比较运算符</h3><table><thead><tr><th>运算符</th><th>含义</th></tr></thead><tbody><tr><td><code>&gt;</code></td><td>大于</td></tr><tr><td><code>&gt;=</code></td><td>大于等于</td></tr><tr><td><code>&lt;</code></td><td>小于</td></tr><tr><td><code>&lt;=</code></td><td>小于等于</td></tr><tr><td><code>==</code></td><td>等于</td></tr><tr><td><code>!=</code> / <code>&lt;&gt;</code></td><td>不等于</td></tr><tr><td><code>BETWEEN ... AND ...</code></td><td>在指定范围内</td></tr><tr><td><code>NOT BETWEEN ... AND ...</code></td><td>不在指定范围内</td></tr><tr><td><code>LIKE</code></td><td>匹配简单模式</td></tr><tr><td><code>NOT LIKE</code></td><td>无法匹配简单模式</td></tr><tr><td><code>REGEXP</code></td><td>匹配正则表达式</td></tr><tr><td><code>NOT REGEXP</code></td><td>无法匹配正则表达式</td></tr><tr><td><code>IS NULL</code></td><td>是空值</td></tr><tr><td><code>IS NOT NULL</code></td><td>不是空值</td></tr><tr><td><code>IN</code> / <code>CONTAINS</code></td><td>是指定列表中的值</td></tr><tr><td><code>NOT IN</code> / <code>NOT CONTAINS</code></td><td>不是指定列表中的值</td></tr></tbody></table>',2),N=n('<h3 id="逻辑运算符" tabindex="-1"><a class="header-anchor" href="#逻辑运算符" aria-hidden="true">#</a> 逻辑运算符</h3><table><thead><tr><th>运算符</th><th>含义</th></tr></thead><tbody><tr><td><code>NOT</code> / <code>!</code></td><td>取非（单目）</td></tr><tr><td><code>AND</code> / <code>&amp;</code> / <code>&amp;&amp;</code></td><td>逻辑与</td></tr><tr><td><code>OR</code>/ | / ||</td><td>逻辑或</td></tr></tbody></table>',2),L=n(`<h3 id="运算符优先级" tabindex="-1"><a class="header-anchor" href="#运算符优先级" aria-hidden="true">#</a> 运算符优先级</h3><p>运算符的优先级从高到低如下所示排列，同一行的运算符具有相同的优先级。</p><div class="language-sql line-numbers-mode" data-ext="sql"><pre class="language-sql"><code><span class="token operator">!</span><span class="token punctuation">,</span> <span class="token operator">-</span> <span class="token punctuation">(</span>单目<span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token operator">+</span> <span class="token punctuation">(</span>单目<span class="token punctuation">)</span>
<span class="token operator">*</span><span class="token punctuation">,</span> <span class="token operator">/</span><span class="token punctuation">,</span> <span class="token operator">DIV</span><span class="token punctuation">,</span> <span class="token operator">%</span><span class="token punctuation">,</span> MOD
<span class="token operator">-</span><span class="token punctuation">,</span> <span class="token operator">+</span>
<span class="token operator">=</span><span class="token punctuation">,</span> <span class="token operator">=</span><span class="token operator">=</span><span class="token punctuation">,</span> <span class="token operator">&lt;=&gt;</span><span class="token punctuation">,</span> <span class="token operator">&gt;=</span><span class="token punctuation">,</span> <span class="token operator">&gt;</span><span class="token punctuation">,</span> <span class="token operator">&lt;=</span><span class="token punctuation">,</span> <span class="token operator">&lt;</span><span class="token punctuation">,</span> <span class="token operator">&lt;&gt;</span><span class="token punctuation">,</span> <span class="token operator">!=</span>
<span class="token operator">LIKE</span><span class="token punctuation">,</span> <span class="token operator">REGEXP</span><span class="token punctuation">,</span> <span class="token operator">NOT</span> <span class="token operator">LIKE</span><span class="token punctuation">,</span> <span class="token operator">NOT</span> <span class="token operator">REGEXP</span>
<span class="token operator">BETWEEN</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token operator">AND</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">,</span> <span class="token operator">NOT</span> <span class="token operator">BETWEEN</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token operator">AND</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span>
<span class="token operator">IS</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token operator">IS</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span>
<span class="token operator">IN</span><span class="token punctuation">,</span> <span class="token keyword">CONTAINS</span><span class="token punctuation">,</span> <span class="token operator">NOT</span> <span class="token operator">IN</span><span class="token punctuation">,</span> <span class="token operator">NOT</span> <span class="token keyword">CONTAINS</span>
<span class="token operator">AND</span><span class="token punctuation">,</span> <span class="token operator">&amp;</span><span class="token punctuation">,</span> <span class="token operator">&amp;&amp;</span>
<span class="token operator">OR</span><span class="token punctuation">,</span> <span class="token operator">|</span><span class="token punctuation">,</span> <span class="token operator">||</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></div><h2 id="内置函数列表" tabindex="-1"><a class="header-anchor" href="#内置函数列表" aria-hidden="true">#</a> 内置函数列表</h2><p>列表中的函数无须注册即可在 IoTDB 中使用，数据函数质量库中的函数需要参考注册步骤进行注册后才能使用。</p><h3 id="聚合函数" tabindex="-1"><a class="header-anchor" href="#聚合函数" aria-hidden="true">#</a> 聚合函数</h3>`,6),I=t("thead",null,[t("tr",null,[t("th",null,"函数名"),t("th",null,"功能描述"),t("th",null,"允许的输入类型"),t("th",null,"输出类型")])],-1),_=t("tr",null,[t("td",null,"SUM"),t("td",null,"求和。"),t("td",null,"INT32 INT64 FLOAT DOUBLE"),t("td",null,"DOUBLE")],-1),b=t("tr",null,[t("td",null,"COUNT"),t("td",null,"计算数据点数。"),t("td",null,"所有类型"),t("td",null,"INT")],-1),A=t("tr",null,[t("td",null,"AVG"),t("td",null,"求平均值。"),t("td",null,"INT32 INT64 FLOAT DOUBLE"),t("td",null,"DOUBLE")],-1),U=t("tr",null,[t("td",null,"EXTREME"),t("td",null,"求具有最大绝对值的值。如果正值和负值的最大绝对值相等，则返回正值。"),t("td",null,"INT32 INT64 FLOAT DOUBLE"),t("td",null,"与输入类型一致")],-1),D=t("tr",null,[t("td",null,"MAX_VALUE"),t("td",null,"求最大值。"),t("td",null,"INT32 INT64 FLOAT DOUBLE"),t("td",null,"与输入类型一致")],-1),B=t("tr",null,[t("td",null,"MIN_VALUE"),t("td",null,"求最小值。"),t("td",null,"INT32 INT64 FLOAT DOUBLE"),t("td",null,"与输入类型一致")],-1),k=t("tr",null,[t("td",null,"FIRST_VALUE"),t("td",null,"求时间戳最小的值。"),t("td",null,"所有类型"),t("td",null,"与输入类型一致")],-1),m=t("tr",null,[t("td",null,"LAST_VALUE"),t("td",null,"求时间戳最大的值。"),t("td",null,"所有类型"),t("td",null,"与输入类型一致")],-1),F=t("tr",null,[t("td",null,"MAX_TIME"),t("td",null,"求最大时间戳。"),t("td",null,"所有类型"),t("td",null,"Timestamp")],-1),g=t("tr",null,[t("td",null,"MIN_TIME"),t("td",null,"求最小时间戳。"),t("td",null,"所有类型"),t("td",null,"Timestamp")],-1),f=t("td",null,null,-1),S=t("td",null,null,-1),x=t("td",null,null,-1),M=n('<h3 id="数学函数" tabindex="-1"><a class="header-anchor" href="#数学函数" aria-hidden="true">#</a> 数学函数</h3><table><thead><tr><th>函数名</th><th>输入序列类型</th><th>输出序列类型</th><th>Java 标准库中的对应实现</th></tr></thead><tbody><tr><td>SIN</td><td>INT32 / INT64 / FLOAT / DOUBLE</td><td>DOUBLE</td><td>Math#sin(double)</td></tr><tr><td>COS</td><td>INT32 / INT64 / FLOAT / DOUBLE</td><td>DOUBLE</td><td>Math#cos(double)</td></tr><tr><td>TAN</td><td>INT32 / INT64 / FLOAT / DOUBLE</td><td>DOUBLE</td><td>Math#tan(double)</td></tr><tr><td>ASIN</td><td>INT32 / INT64 / FLOAT / DOUBLE</td><td>DOUBLE</td><td>Math#asin(double)</td></tr><tr><td>ACOS</td><td>INT32 / INT64 / FLOAT / DOUBLE</td><td>DOUBLE</td><td>Math#acos(double)</td></tr><tr><td>ATAN</td><td>INT32 / INT64 / FLOAT / DOUBLE</td><td>DOUBLE</td><td>Math#atan(double)</td></tr><tr><td>SINH</td><td>INT32 / INT64 / FLOAT / DOUBLE</td><td>DOUBLE</td><td>Math#sinh(double)</td></tr><tr><td>COSH</td><td>INT32 / INT64 / FLOAT / DOUBLE</td><td>DOUBLE</td><td>Math#cosh(double)</td></tr><tr><td>TANH</td><td>INT32 / INT64 / FLOAT / DOUBLE</td><td>DOUBLE</td><td>Math#tanh(double)</td></tr><tr><td>DEGREES</td><td>INT32 / INT64 / FLOAT / DOUBLE</td><td>DOUBLE</td><td>Math#toDegrees(double)</td></tr><tr><td>RADIANS</td><td>INT32 / INT64 / FLOAT / DOUBLE</td><td>DOUBLE</td><td>Math#toRadians(double)</td></tr><tr><td>ABS</td><td>INT32 / INT64 / FLOAT / DOUBLE</td><td>与输入序列的实际类型一致</td><td>Math#abs(int) / Math#abs(long) /Math#abs(float) /Math#abs(double)</td></tr><tr><td>SIGN</td><td>INT32 / INT64 / FLOAT / DOUBLE</td><td>DOUBLE</td><td>Math#signum(double)</td></tr><tr><td>CEIL</td><td>INT32 / INT64 / FLOAT / DOUBLE</td><td>DOUBLE</td><td>Math#ceil(double)</td></tr><tr><td>FLOOR</td><td>INT32 / INT64 / FLOAT / DOUBLE</td><td>DOUBLE</td><td>Math#floor(double)</td></tr><tr><td>ROUND</td><td>INT32 / INT64 / FLOAT / DOUBLE</td><td>DOUBLE</td><td>Math#rint(double)</td></tr><tr><td>EXP</td><td>INT32 / INT64 / FLOAT / DOUBLE</td><td>DOUBLE</td><td>Math#exp(double)</td></tr><tr><td>LN</td><td>INT32 / INT64 / FLOAT / DOUBLE</td><td>DOUBLE</td><td>Math#log(double)</td></tr><tr><td>LOG10</td><td>INT32 / INT64 / FLOAT / DOUBLE</td><td>DOUBLE</td><td>Math#log10(double)</td></tr><tr><td>SQRT</td><td>INT32 / INT64 / FLOAT / DOUBLE</td><td>DOUBLE</td><td>Math#sqrt(double)</td></tr></tbody></table>',2),v=n('<h3 id="比较函数" tabindex="-1"><a class="header-anchor" href="#比较函数" aria-hidden="true">#</a> 比较函数</h3><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>ON_OFF</td><td>INT32 / INT64 / FLOAT / DOUBLE</td><td><code>threshold</code>:DOUBLE</td><td>BOOLEAN</td><td>返回<code>ts_value &gt;= threshold</code>的bool值</td></tr><tr><td>IN_RANGE</td><td>INT32 / INT64 / FLOAT / DOUBLE</td><td><code>lower</code>:DOUBLE<br><code>upper</code>:DOUBLE</td><td>BOOLEAN</td><td>返回<code>ts_value &gt;= lower &amp;&amp; ts_value &lt;= upper</code>的bool值</td></tr></tbody></table>',2),y=n('<h3 id="字符串处理函数" tabindex="-1"><a class="header-anchor" href="#字符串处理函数" aria-hidden="true">#</a> 字符串处理函数</h3><table><thead><tr><th>函数名</th><th>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>功能描述</th></tr></thead><tbody><tr><td>STRING_CONTAINS</td><td>TEXT</td><td><code>s</code>: 待搜寻的字符串</td><td>BOOLEAN</td><td>判断字符串中是否存在<code>s</code></td></tr><tr><td>STRING_MATCHES</td><td>TEXT</td><td><code>regex</code>: Java 标准库风格的正则表达式</td><td>BOOLEAN</td><td>判断字符串是否能够被正则表达式<code>regex</code>匹配</td></tr><tr><td>LENGTH</td><td>TEXT</td><td>无</td><td>INT32</td><td>返回字符串的长度</td></tr><tr><td>LOCATE</td><td>TEXT</td><td><code>target</code>: 需要被定位的子串 <br> <code>reverse</code>: 指定是否需要倒序定位，默认值为<code>false</code>, 即从左至右定位</td><td>INT32</td><td>获取<code>target</code>子串第一次出现在输入序列的位置，如果输入序列中不包含<code>target</code>则返回 -1</td></tr><tr><td>STARTSWITH</td><td>TEXT</td><td><code>target</code>: 需要匹配的前缀</td><td>BOOLEAN</td><td>判断字符串是否有指定前缀</td></tr><tr><td>ENDSWITH</td><td>TEXT</td><td><code>target</code>: 需要匹配的后缀</td><td>BOOLEAN</td><td>判断字符串是否有指定后缀</td></tr><tr><td>CONCAT</td><td>TEXT</td><td><code>targets</code>: 一系列 K-V, key需要以<code>target</code>为前缀且不重复, value是待拼接的字符串。<br><code>series_behind</code>: 指定拼接时时间序列是否在后面，默认为<code>false</code>。</td><td>TEXT</td><td>拼接字符串和<code>target</code>字串</td></tr><tr><td>SUBSTR</td><td>TEXT</td><td><code>start</code>: 指定子串开始下标 <br><code>end</code>: 指定子串结束下标</td><td>TEXT</td><td>获取下标从<code>start</code>到<code>end - 1</code>的子串</td></tr><tr><td>UPPER</td><td>TEXT</td><td>无</td><td>TEXT</td><td>将字符串转化为大写</td></tr><tr><td>LOWER</td><td>TEXT</td><td>无</td><td>TEXT</td><td>将字符串转化为小写</td></tr><tr><td>TRIM</td><td>TEXT</td><td>无</td><td>TEXT</td><td>移除字符串前后的空格</td></tr><tr><td>STRCMP</td><td>TEXT</td><td>无</td><td>TEXT</td><td>用于比较两个输入序列，如果值相同返回 <code>0</code> , 序列1的值小于序列2的值返回一个<code>负数</code>，序列1的值大于序列2的值返回一个<code>正数</code></td></tr></tbody></table>',2),R=n('<h3 id="数据类型转换函数" tabindex="-1"><a class="header-anchor" href="#数据类型转换函数" aria-hidden="true">#</a> 数据类型转换函数</h3><table><thead><tr><th>函数名</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>CAST</td><td><code>type</code>:输出的数据点的类型，只能是 INT32 / INT64 / FLOAT / DOUBLE / BOOLEAN / TEXT</td><td>由输入属性参数<code>type</code>决定</td><td>将数据转换为<code>type</code>参数指定的类型。</td></tr></tbody></table>',2),C=n('<h3 id="常序列生成函数" tabindex="-1"><a class="header-anchor" href="#常序列生成函数" aria-hidden="true">#</a> 常序列生成函数</h3><table><thead><tr><th>函数名</th><th>必要的属性参数</th><th>输出序列类型</th><th>功能描述</th></tr></thead><tbody><tr><td>CONST</td><td><code>value</code>: 输出的数据点的值 <br><code>type</code>: 输出的数据点的类型，只能是 INT32 / INT64 / FLOAT / DOUBLE / BOOLEAN / TEXT</td><td>由输入属性参数 <code>type</code> 决定</td><td>根据输入属性 <code>value</code> 和 <code>type</code> 输出用户指定的常序列。</td></tr><tr><td>PI</td><td>无</td><td>DOUBLE</td><td>常序列的值：<code>π</code> 的 <code>double</code> 值，圆的周长与其直径的比值，即圆周率，等于 <em>Java标准库</em> 中的<code>Math.PI</code>。</td></tr><tr><td>E</td><td>无</td><td>DOUBLE</td><td>常序列的值：<code>e</code> 的 <code>double</code> 值，自然对数的底，它等于 <em>Java 标准库</em> 中的 <code>Math.E</code>。</td></tr></tbody></table>',2),V=n('<h3 id="选择函数" tabindex="-1"><a class="header-anchor" href="#选择函数" aria-hidden="true">#</a> 选择函数</h3><table><thead><tr><th>函数名</th><th>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>功能描述</th></tr></thead><tbody><tr><td>TOP_K</td><td>INT32 / INT64 / FLOAT / DOUBLE / TEXT</td><td><code>k</code>: 最多选择的数据点数，必须大于 0 小于等于 1000</td><td>与输入序列的实际类型一致</td><td>返回某时间序列中值最大的<code>k</code>个数据点。若多于<code>k</code>个数据点的值并列最大，则返回时间戳最小的数据点。</td></tr><tr><td>BOTTOM_K</td><td>INT32 / INT64 / FLOAT / DOUBLE / TEXT</td><td><code>k</code>: 最多选择的数据点数，必须大于 0 小于等于 1000</td><td>与输入序列的实际类型一致</td><td>返回某时间序列中值最小的<code>k</code>个数据点。若多于<code>k</code>个数据点的值并列最小，则返回时间戳最小的数据点。</td></tr></tbody></table>',2),X=n('<h3 id="区间查询函数" tabindex="-1"><a class="header-anchor" href="#区间查询函数" aria-hidden="true">#</a> 区间查询函数</h3><table><thead><tr><th>函数名</th><th>输入序列类型</th><th>属性参数</th><th>输出序列类型</th><th>功能描述</th></tr></thead><tbody><tr><td>ZERO_DURATION</td><td>INT32/ INT64/ FLOAT/ DOUBLE/ BOOLEAN</td><td><code>min</code>:可选，默认值0<br><code>max</code>:可选，默认值<code>Long.MAX_VALUE</code></td><td>Long</td><td>返回时间序列连续为0(false)的开始时间与持续时间，持续时间t(单位ms)满足<code>t &gt;= min &amp;&amp; t &lt;= max</code></td></tr><tr><td>NON_ZERO_DURATION</td><td>INT32/ INT64/ FLOAT/ DOUBLE/ BOOLEAN</td><td><code>min</code>:可选，默认值0<br><code>max</code>:可选，默认值<code>Long.MAX_VALUE</code></td><td>Long</td><td>返回时间序列连续不为0(false)的开始时间与持续时间，持续时间t(单位ms)满足<code>t &gt;= min &amp;&amp; t &lt;= max</code></td></tr><tr><td>ZERO_COUNT</td><td>INT32/ INT64/ FLOAT/ DOUBLE/ BOOLEAN</td><td><code>min</code>:可选，默认值1<br><code>max</code>:可选，默认值<code>Long.MAX_VALUE</code></td><td>Long</td><td>返回时间序列连续为0(false)的开始时间与其后数据点的个数，数据点个数n满足<code>n &gt;= min &amp;&amp; n &lt;= max</code></td></tr><tr><td>NON_ZERO_COUNT</td><td>INT32/ INT64/ FLOAT/ DOUBLE/ BOOLEAN</td><td><code>min</code>:可选，默认值1<br><code>max</code>:可选，默认值<code>Long.MAX_VALUE</code></td><td>Long</td><td>返回时间序列连续不为0(false)的开始时间与其后数据点的个数，数据点个数n满足<code>n &gt;= min &amp;&amp; n &lt;= max</code></td></tr></tbody></table>',2),G=n('<h3 id="趋势计算函数" tabindex="-1"><a class="header-anchor" href="#趋势计算函数" aria-hidden="true">#</a> 趋势计算函数</h3><table><thead><tr><th>函数名</th><th>输入序列类型</th><th>输出序列类型</th><th>功能描述</th></tr></thead><tbody><tr><td>TIME_DIFFERENCE</td><td>INT32 / INT64 / FLOAT / DOUBLE / BOOLEAN / TEXT</td><td>INT64</td><td>统计序列中某数据点的时间戳与前一数据点时间戳的差。范围内第一个数据点没有对应的结果输出。</td></tr><tr><td>DIFFERENCE</td><td>INT32 / INT64 / FLOAT / DOUBLE</td><td>与输入序列的实际类型一致</td><td>统计序列中某数据点的值与前一数据点的值的差。范围内第一个数据点没有对应的结果输出。</td></tr><tr><td>NON_NEGATIVE_DIFFERENCE</td><td>INT32 / INT64 / FLOAT / DOUBLE</td><td>与输入序列的实际类型一致</td><td>统计序列中某数据点的值与前一数据点的值的差的绝对值。范围内第一个数据点没有对应的结果输出。</td></tr><tr><td>DERIVATIVE</td><td>INT32 / INT64 / FLOAT / DOUBLE</td><td>DOUBLE</td><td>统计序列中某数据点相对于前一数据点的变化率，数量上等同于 DIFFERENCE / TIME_DIFFERENCE。范围内第一个数据点没有对应的结果输出。</td></tr><tr><td>NON_NEGATIVE_DERIVATIVE</td><td>INT32 / INT64 / FLOAT / DOUBLE</td><td>DOUBLE</td><td>统计序列中某数据点相对于前一数据点的变化率的绝对值，数量上等同于 NON_NEGATIVE_DIFFERENCE / TIME_DIFFERENCE。范围内第一个数据点没有对应的结果输出。</td></tr></tbody></table><table><thead><tr><th>函数名</th><th>输入序列类型</th><th>参数</th><th>输出序列类型</th><th>功能描述</th></tr></thead><tbody><tr><td>DIFF</td><td>INT32 / INT64 / FLOAT / DOUBLE</td><td><code>ignoreNull</code>：可选，默认为true；为true时，前一个数据点值为null时，忽略该数据点继续向前找到第一个出现的不为null的值；为false时，如果前一个数据点为null，则不忽略，使用null进行相减，结果也为null</td><td>DOUBLE</td><td>统计序列中某数据点的值与前一数据点的值的差。第一个数据点没有对应的结果输出，输出值为null</td></tr></tbody></table>',3),w=n('<h3 id="采样函数" tabindex="-1"><a class="header-anchor" href="#采样函数" aria-hidden="true">#</a> 采样函数</h3><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><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><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><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><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><h2 id="数据质量函数库" tabindex="-1"><a class="header-anchor" href="#数据质量函数库" aria-hidden="true">#</a> 数据质量函数库</h2><p>对基于时序数据的应用而言，数据质量至关重要。基于用户自定义函数能力，IoTDB 提供了一系列关于数据质量的函数，包括数据画像、数据质量评估与修复等，能够满足工业领域对数据质量的需求。</p><p><strong>该函数库中的函数不是内置函数，使用前要先加载到系统中。</strong> 操作流程如下：</p>',5),z={href:"https://archive.apache.org/dist/iotdb/1.0.1/apache-iotdb-1.0.1-library-udf-bin.zip",target:"_blank",rel:"noopener noreferrer"},P=t("li",null,[d("将 jar 包复制到 IoTDB 程序目录的 "),t("code",null,"ext\\udf"),d(" 目录下 (若您使用的是集群，请将jar包复制到所有DataNode的该目录下)；")],-1),W=t("li",null,"启动 IoTDB；",-1),K=t("li",null,[d("将注册脚本复制到 IoTDB 的程序目录下（与"),t("code",null,"sbin"),d("目录同级的根目录下），修改脚本中的参数（如果需要）并运行注册脚本以注册 UDF。")],-1);function H(Q,Z){const o=s("RouterLink"),c=s("ExternalLinkIcon");return p(),h("div",null,[r(`

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