| import{_ as t,C as i,O as o,P as r,ah as l,Q as s,U as n,ai as c,aW as e}from"./framework-62ad666a.js";const p={},d=e('<h2 id="lambda-表达式" tabindex="-1"><a class="header-anchor" href="#lambda-表达式" aria-hidden="true">#</a> Lambda 表达式</h2><h3 id="jexl-自定义函数" tabindex="-1"><a class="header-anchor" href="#jexl-自定义函数" aria-hidden="true">#</a> JEXL 自定义函数</h3><h4 id="函数简介" tabindex="-1"><a class="header-anchor" href="#函数简介" aria-hidden="true">#</a> 函数简介</h4><p>Java Expression Language (JEXL) 是一个表达式语言引擎。我们使用 JEXL 来扩展 UDF，在命令行中，通过简易的 lambda 表达式来实现 UDF。</p>',4),u={href:"https://commons.apache.org/proper/commons-jexl/apidocs/org/apache/commons/jexl3/package-summary.html#customization",target:"_blank",rel:"noopener noreferrer"},m=e(`<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>JEXL</td><td>INT32 / INT64 / FLOAT / DOUBLE / TEXT / BOOLEAN</td><td><code>expr</code>是一个支持标准的一元或多元参数的lambda表达式，符合<code>x -> {...}</code>或<code>(x, y, z) -> {...}</code>的格式，例如<code>x -> {x * 2}</code>, <code>(x, y, z) -> {x + y * z}</code></td><td>INT32 / INT64 / FLOAT / DOUBLE / TEXT / BOOLEAN</td><td>返回将输入的时间序列通过lambda表达式变换的序列</td></tr></tbody></table><h4 id="使用示例" tabindex="-1"><a class="header-anchor" href="#使用示例" aria-hidden="true">#</a> 使用示例</h4><p>输入序列：</p><div class="language-text line-numbers-mode" data-ext="text"><pre class="language-text"><code>IoTDB> select * from root.ln.wf01.wt01; |
| +-----------------------------+---------------------+--------------------+-----------------------------+ |
| | Time|root.ln.wf01.wt01.str|root.ln.wf01.wt01.st|root.ln.wf01.wt01.temperature| |
| +-----------------------------+---------------------+--------------------+-----------------------------+ |
| |1970-01-01T08:00:00.000+08:00| str| 10.0| 0.0| |
| |1970-01-01T08:00:00.001+08:00| str| 20.0| 1.0| |
| |1970-01-01T08:00:00.002+08:00| str| 30.0| 2.0| |
| |1970-01-01T08:00:00.003+08:00| str| 40.0| 3.0| |
| |1970-01-01T08:00:00.004+08:00| str| 50.0| 4.0| |
| |1970-01-01T08:00:00.005+08:00| str| 60.0| 5.0| |
| |1970-01-01T08:00:00.006+08:00| str| 70.0| 6.0| |
| |1970-01-01T08:00:00.007+08:00| str| 80.0| 7.0| |
| |1970-01-01T08:00:00.008+08:00| str| 90.0| 8.0| |
| |1970-01-01T08:00:00.009+08:00| str| 100.0| 9.0| |
| |1970-01-01T08:00:00.010+08:00| str| 110.0| 10.0| |
| +-----------------------------+---------------------+--------------------+-----------------------------+ |
| </code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><p>用于查询的SQL语句：</p><div class="language-sql line-numbers-mode" data-ext="sql"><pre class="language-sql"><code><span class="token keyword">select</span> jexl<span class="token punctuation">(</span>temperature<span class="token punctuation">,</span> <span class="token string">'expr'</span><span class="token operator">=</span><span class="token string">'x -> {x + x}'</span><span class="token punctuation">)</span> <span class="token keyword">as</span> jexl1<span class="token punctuation">,</span> jexl<span class="token punctuation">(</span>temperature<span class="token punctuation">,</span> <span class="token string">'expr'</span><span class="token operator">=</span><span class="token string">'x -> {x * 3}'</span><span class="token punctuation">)</span> <span class="token keyword">as</span> jexl2<span class="token punctuation">,</span> jexl<span class="token punctuation">(</span>temperature<span class="token punctuation">,</span> <span class="token string">'expr'</span><span class="token operator">=</span><span class="token string">'x -> {x * x}'</span><span class="token punctuation">)</span> <span class="token keyword">as</span> jexl3<span class="token punctuation">,</span> jexl<span class="token punctuation">(</span>temperature<span class="token punctuation">,</span> <span class="token string">'expr'</span><span class="token operator">=</span><span class="token string">'x -> {multiply(x, 100)}'</span><span class="token punctuation">)</span> <span class="token keyword">as</span> jexl4<span class="token punctuation">,</span> jexl<span class="token punctuation">(</span>temperature<span class="token punctuation">,</span> st<span class="token punctuation">,</span> <span class="token string">'expr'</span><span class="token operator">=</span><span class="token string">'(x, y) -> {x + y}'</span><span class="token punctuation">)</span> <span class="token keyword">as</span> jexl5<span class="token punctuation">,</span> jexl<span class="token punctuation">(</span>temperature<span class="token punctuation">,</span> st<span class="token punctuation">,</span> str<span class="token punctuation">,</span> <span class="token string">'expr'</span><span class="token operator">=</span><span class="token string">'(x, y, z) -> {x + y + z}'</span><span class="token punctuation">)</span> <span class="token keyword">as</span> jexl6 <span class="token keyword">from</span> root<span class="token punctuation">.</span>ln<span class="token punctuation">.</span>wf01<span class="token punctuation">.</span>wt01<span class="token punctuation">;</span> |
| </code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></div></div><p>输出序列：</p><div class="language-text line-numbers-mode" data-ext="text"><pre class="language-text"><code>+-----------------------------+-----+-----+-----+------+-----+--------+ |
| | Time|jexl1|jexl2|jexl3| jexl4|jexl5| jexl6| |
| +-----------------------------+-----+-----+-----+------+-----+--------+ |
| |1970-01-01T08:00:00.000+08:00| 0.0| 0.0| 0.0| 0.0| 10.0| 10.0str| |
| |1970-01-01T08:00:00.001+08:00| 2.0| 3.0| 1.0| 100.0| 21.0| 21.0str| |
| |1970-01-01T08:00:00.002+08:00| 4.0| 6.0| 4.0| 200.0| 32.0| 32.0str| |
| |1970-01-01T08:00:00.003+08:00| 6.0| 9.0| 9.0| 300.0| 43.0| 43.0str| |
| |1970-01-01T08:00:00.004+08:00| 8.0| 12.0| 16.0| 400.0| 54.0| 54.0str| |
| |1970-01-01T08:00:00.005+08:00| 10.0| 15.0| 25.0| 500.0| 65.0| 65.0str| |
| |1970-01-01T08:00:00.006+08:00| 12.0| 18.0| 36.0| 600.0| 76.0| 76.0str| |
| |1970-01-01T08:00:00.007+08:00| 14.0| 21.0| 49.0| 700.0| 87.0| 87.0str| |
| |1970-01-01T08:00:00.008+08:00| 16.0| 24.0| 64.0| 800.0| 98.0| 98.0str| |
| |1970-01-01T08:00:00.009+08:00| 18.0| 27.0| 81.0| 900.0|109.0|109.0str| |
| |1970-01-01T08:00:00.010+08:00| 20.0| 30.0|100.0|1000.0|120.0|120.0str| |
| +-----------------------------+-----+-----+-----+------+-----+--------+ |
| Total line number = 11 |
| It costs 0.118s |
| </code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div>`,8);function v(h,k){const a=i("ExternalLinkIcon");return o(),r("div",null,[l(` |
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| `),d,s("p",null,[n("lambda 表达式中支持的运算符详见链接 "),s("a",u,[n("JEXL 中 lambda 表达式支持的运算符"),c(a)]),n(" 。")]),m])}const b=t(p,[["render",v],["__file","Lambda.html.vue"]]);export{b as default}; |
