| import{_ as n,o as e,c as s,a as t,f as a}from"./app-9073a2e6.js";const o={},i=a(`<h2 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</h2><p>常序列生成函数用于生成所有数据点的值都相同的时间序列。</p><p>常序列生成函数接受一个或者多个时间序列输入，其输出的数据点的时间戳集合是这些输入序列时间戳集合的并集。</p><p>目前 IoTDB 支持如下常序列生成函数：</p><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><p>例如：</p><div class="language-sql line-numbers-mode" data-ext="sql"><pre class="language-sql"><code><span class="token keyword">select</span> s1<span class="token punctuation">,</span> s2<span class="token punctuation">,</span> const<span class="token punctuation">(</span>s1<span class="token punctuation">,</span> <span class="token string">'value'</span><span class="token operator">=</span><span class="token string">'1024'</span><span class="token punctuation">,</span> <span class="token string">'type'</span><span class="token operator">=</span><span class="token string">'INT64'</span><span class="token punctuation">)</span><span class="token punctuation">,</span> pi<span class="token punctuation">(</span>s2<span class="token punctuation">)</span><span class="token punctuation">,</span> e<span class="token punctuation">(</span>s1<span class="token punctuation">,</span> s2<span class="token punctuation">)</span> <span class="token keyword">from</span> root<span class="token punctuation">.</span>sg1<span class="token punctuation">.</span>d1<span class="token punctuation">;</span> |
| </code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></div></div><p>结果：</p><div class="language-text line-numbers-mode" data-ext="text"><pre class="language-text"><code>select s1, s2, const(s1, 'value'='1024', 'type'='INT64'), pi(s2), e(s1, s2) from root.sg1.d1; |
| +-----------------------------+--------------+--------------+-----------------------------------------------------+------------------+---------------------------------+ |
| | Time|root.sg1.d1.s1|root.sg1.d1.s2|const(root.sg1.d1.s1, "value"="1024", "type"="INT64")|pi(root.sg1.d1.s2)|e(root.sg1.d1.s1, root.sg1.d1.s2)| |
| +-----------------------------+--------------+--------------+-----------------------------------------------------+------------------+---------------------------------+ |
| |1970-01-01T08:00:00.000+08:00| 0.0| 0.0| 1024| 3.141592653589793| 2.718281828459045| |
| |1970-01-01T08:00:00.001+08:00| 1.0| null| 1024| null| 2.718281828459045| |
| |1970-01-01T08:00:00.002+08:00| 2.0| null| 1024| null| 2.718281828459045| |
| |1970-01-01T08:00:00.003+08:00| null| 3.0| null| 3.141592653589793| 2.718281828459045| |
| |1970-01-01T08:00:00.004+08:00| null| 4.0| null| 3.141592653589793| 2.718281828459045| |
| +-----------------------------+--------------+--------------+-----------------------------------------------------+------------------+---------------------------------+ |
| Total line number = 5 |
| It costs 0.005s |
| </code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div>`,9);function d(c,l){return e(),s("div",null,[t(` |
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