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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 data-allow-mismatch="text">2025/4/3</span><meta property="datePublished" content="2025-04-03T10:16:25.000Z"></span><!----><span class="page-reading-time-info" aria-label="阅读时间⌛" data-balloon-pos="up"><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>大约 11 分钟</span><meta property="timeRequired" content="PT11M"></span><!----><!----></div><hr></div><!----><div class="" vp-content><!----><div id="markdown-content"><h1 id="udf" tabindex="-1"><a class="header-anchor" href="#udf"><span>UDF</span></a></h1><h2 id="_1-udf介绍" tabindex="-1"><a class="header-anchor" href="#_1-udf介绍"><span>1. UDF介绍</span></a></h2><p>UDF（User Defined Function）即用户自定义函数，IoTDB 提供多种内置的时序处理函数，也支持扩展自定义函数来满足更多的计算需求。</p><p>IoTDB 表模型中支持三种类型的 UDF ，如下表所示。</p><table><thead><tr><th>UDF 类型</th><th>函数类型</th><th>描述</th></tr></thead><tbody><tr><td><code>UDSF（User-defined Scalar Function）</code></td><td>标量函数</td><td>输入 k 列 1 行数据，输出1 列 1 行数据（一对一）。</td></tr><tr><td><code>UDAF（User-defined Aggregate Function）</code></td><td>聚合函数</td><td>输入k 列 m 行数据，输出1 列 1 行数据（多对一）。</td></tr><tr><td><code>UDTF（User-defined Table Function）</code></td><td>表函数</td><td>输入0或1张表（k 列 m 行），输出1张表（x 行 y 列）。</td></tr></tbody></table><ul><li><code>UDSF</code> 可用于标量函数出现的任何子句和表达式中，如select子句、where子句等。 <ul><li><code>select udsf1(s1) from table1 where udsf2(s1)&gt;0</code></li></ul></li><li><code>UDAF</code> 可用于聚合函数出现的任何子句和表达式中，如select子句、having子句等； <ul><li><code>select udaf1(s1), device_id from table1 group by device_id having udaf2(s1)&gt;0 </code></li></ul></li><li><code>UDTF</code> 可以像关系表一样在from子句中使用； <ul><li><code>select * from udtf(&#39;t1&#39;, bid);</code></li></ul></li></ul><h2 id="_2-udf-管理" tabindex="-1"><a class="header-anchor" href="#_2-udf-管理"><span>2. UDF 管理</span></a></h2><h3 id="_2-1-udf-注册" tabindex="-1"><a class="header-anchor" href="#_2-1-udf-注册"><span>2.1 UDF 注册</span></a></h3><ol><li><p>准备 UDF 实现的 JAR 包，其中包含 UDF 实现类，如<code>org.apache.iotdb.udf.ScalarFunctionExample</code>。</p><p>Jar 包的放置有两种方式：</p></li></ol><ul><li>本地：需要将 JAR 包放置到集群<strong>所有节点</strong>的 <code>ext/udf</code>目录下。</li><li>远端：需要将 JAR 包上传到 URI 服务器上并确保 IoTDB 实例能够访问该 URI 服务器（注册成功后IoTDB 会下载 JAR 包并同步到整个集群）。</li></ul><ol start="2"><li>使用以下 SQL 语句注册 UDF</li></ol><div class="language-sql line-numbers-mode" data-highlighter="shiki" data-ext="sql" style="background-color:#282c34;color:#abb2bf;"><pre class="shiki one-dark-pro vp-code"><code class="language-sql"><span class="line"><span style="color:#C678DD;">CREATE</span><span style="color:#C678DD;"> FUNCTION</span><span style="color:#56B6C2;"> &lt;</span><span style="color:#ABB2BF;">UDF-</span><span style="color:#C678DD;">NAME</span><span style="color:#56B6C2;">&gt;</span><span style="color:#C678DD;"> AS</span><span style="color:#56B6C2;"> &lt;</span><span style="color:#ABB2BF;">UDF-CLASS-FULL-PATHNAME</span><span style="color:#56B6C2;">&gt;</span><span style="color:#ABB2BF;"> (</span><span style="color:#C678DD;">USING</span><span style="color:#ABB2BF;"> URI URI-STRING)</span></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div></div></div><ul><li>示例</li></ul><div class="language-sql line-numbers-mode" data-highlighter="shiki" data-ext="sql" style="background-color:#282c34;color:#abb2bf;"><pre class="shiki one-dark-pro vp-code"><code class="language-sql"><span class="line"><span style="color:#7F848E;font-style:italic;">-- 本地</span></span>
<span class="line"><span style="color:#C678DD;">CREATE</span><span style="color:#C678DD;"> FUNCTION</span><span style="color:#61AFEF;"> contain_null</span><span style="color:#C678DD;"> AS</span><span style="color:#98C379;"> &#39;org.apache.iotdb.udf.ScalarFunctionExample&#39;</span><span style="color:#ABB2BF;">;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#7F848E;font-style:italic;">-- 远端</span></span>
<span class="line"><span style="color:#C678DD;">CREATE</span><span style="color:#C678DD;"> FUNCTION</span><span style="color:#61AFEF;"> contain_null</span><span style="color:#C678DD;"> AS</span><span style="color:#98C379;"> &#39;org.apache.iotdb.udf.ScalarFunctionExample&#39;</span><span style="color:#C678DD;"> USING</span><span style="color:#ABB2BF;"> URI </span><span style="color:#98C379;">&#39;http://jar/example.jar&#39;</span></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><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><strong>注意：</strong></p><ol><li>UDF 在装载过程中无需启停服务器。</li><li>UDF 名称大小写不敏感，不能与 IoTDB 内置函数重名。</li><li>表模型和树模型的 UDF 空间相互独立。</li><li>避免在不同的 JAR 包中创建全类名相同但功能逻辑不同的 UDF 类。如果存在，系统在执行 UDF 时会随机加载其中一个，造成执行行为不一致。</li></ol><h3 id="_2-2-udf-卸载" tabindex="-1"><a class="header-anchor" href="#_2-2-udf-卸载"><span>2.2 UDF 卸载</span></a></h3><p>SQL 语法如下：</p><div class="language-sql line-numbers-mode" data-highlighter="shiki" data-ext="sql" style="background-color:#282c34;color:#abb2bf;"><pre class="shiki one-dark-pro vp-code"><code class="language-sql"><span class="line"><span style="color:#C678DD;">DROP</span><span style="color:#C678DD;"> FUNCTION</span><span style="color:#56B6C2;"> &lt;</span><span style="color:#ABB2BF;">UDF-</span><span style="color:#C678DD;">NAME</span><span style="color:#56B6C2;">&gt;</span></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div></div></div><p>示例：卸载上述例子的 UDF：</p><div class="language-sql line-numbers-mode" data-highlighter="shiki" data-ext="sql" style="background-color:#282c34;color:#abb2bf;"><pre class="shiki one-dark-pro vp-code"><code class="language-sql"><span class="line"><span style="color:#C678DD;">DROP</span><span style="color:#C678DD;"> FUNCTION</span><span style="color:#ABB2BF;"> contain_null</span></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div></div></div><h3 id="_2-3-udf-查看" tabindex="-1"><a class="header-anchor" href="#_2-3-udf-查看"><span>2.3 UDF 查看</span></a></h3><ul><li>如果 State 为 UNAVAILABLE，可能是在注册或卸载过程中系统发生了错误，请查看系统日志进行排查，重新注册或卸载 UDF 直至成功即可。</li></ul><div class="language-sql line-numbers-mode" data-highlighter="shiki" data-ext="sql" style="background-color:#282c34;color:#abb2bf;"><pre class="shiki one-dark-pro vp-code"><code class="language-sql"><span class="line"><span style="color:#ABB2BF;">SHOW FUNCTIONS</span></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div></div></div><h3 id="_2-4-udf-配置" tabindex="-1"><a class="header-anchor" href="#_2-4-udf-配置"><span>2.4 UDF 配置</span></a></h3><ul><li>可以在 <code>iotdb-system.properties</code> 中配置 UDF Jar 文件的存储目录：</li></ul><div class="language-properties line-numbers-mode" data-highlighter="shiki" data-ext="properties" style="background-color:#282c34;color:#abb2bf;"><pre class="shiki one-dark-pro vp-code"><code class="language-properties"><span class="line"><span style="color:#7F848E;font-style:italic;"># UDF lib dir</span></span>
<span class="line"><span style="color:#C678DD;">udf_lib_dir</span><span style="color:#ABB2BF;">=</span><span style="color:#98C379;">ext/udf</span></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div></div></div><h2 id="_3-udf-开发" tabindex="-1"><a class="header-anchor" href="#_3-udf-开发"><span>3. UDF 开发</span></a></h2><h3 id="_3-1-udf-依赖" tabindex="-1"><a class="header-anchor" href="#_3-1-udf-依赖"><span>3.1 UDF 依赖</span></a></h3><p>可以从 <a href="http://search.maven.org/" target="_blank" rel="noopener noreferrer">Maven 库</a> 中搜索下面示例中的依赖，请注意选择和目标 IoTDB 服务器版本相同的依赖版本。</p><div class="language-xml line-numbers-mode" data-highlighter="shiki" data-ext="xml" style="background-color:#282c34;color:#abb2bf;"><pre class="shiki one-dark-pro vp-code"><code class="language-xml"><span class="line"><span style="color:#ABB2BF;">&lt;</span><span style="color:#E06C75;">dependency</span><span style="color:#ABB2BF;">&gt;</span></span>
<span class="line"><span style="color:#ABB2BF;"> &lt;</span><span style="color:#E06C75;">groupId</span><span style="color:#ABB2BF;">&gt;org.apache.iotdb&lt;/</span><span style="color:#E06C75;">groupId</span><span style="color:#ABB2BF;">&gt;</span></span>
<span class="line"><span style="color:#ABB2BF;"> &lt;</span><span style="color:#E06C75;">artifactId</span><span style="color:#ABB2BF;">&gt;udf-api&lt;/</span><span style="color:#E06C75;">artifactId</span><span style="color:#ABB2BF;">&gt;</span></span>
<span class="line"><span style="color:#ABB2BF;"> &lt;</span><span style="color:#E06C75;">version</span><span style="color:#ABB2BF;">&gt;2.0.0&lt;/</span><span style="color:#E06C75;">version</span><span style="color:#ABB2BF;">&gt;</span></span>
<span class="line"><span style="color:#ABB2BF;"> &lt;</span><span style="color:#E06C75;">scope</span><span style="color:#ABB2BF;">&gt;provided&lt;/</span><span style="color:#E06C75;">scope</span><span style="color:#ABB2BF;">&gt;</span></span>
<span class="line"><span style="color:#ABB2BF;">&lt;/</span><span style="color:#E06C75;">dependency</span><span style="color:#ABB2BF;">&gt;</span></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><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><h3 id="_3-2-标量函数-udsf" tabindex="-1"><a class="header-anchor" href="#_3-2-标量函数-udsf"><span>3.2 标量函数（UDSF）</span></a></h3><p>编写一个 UDSF 需要实现<code>org.apache.iotdb.udf.api.relational.ScalarFunction</code>接口。</p><div class="language-java line-numbers-mode" data-highlighter="shiki" data-ext="java" style="background-color:#282c34;color:#abb2bf;"><pre class="shiki one-dark-pro vp-code"><code class="language-java"><span class="line"><span style="color:#C678DD;">public</span><span style="color:#C678DD;"> interface</span><span style="color:#E5C07B;"> ScalarFunction</span><span style="color:#C678DD;"> extends</span><span style="color:#E5C07B;"> SQLFunction</span><span style="color:#ABB2BF;"> {</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> /**</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * In this method, the user need to do the following things:</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> *</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * &lt;ul&gt;</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * &lt;li&gt;Validate {@linkplain FunctionArguments}. Throw {@link UDFArgumentNotValidException} if</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * any parameter is not valid.</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * &lt;li&gt;Use {@linkplain FunctionArguments} to get input data types and infer output data type.</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * &lt;li&gt;Construct and return a {@linkplain ScalarFunctionAnalysis} object.</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * &lt;/ul&gt;</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> *</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * </span><span style="color:#C678DD;font-style:italic;">@param</span><span style="color:#E06C75;font-style:italic;"> arguments</span><span style="color:#7F848E;font-style:italic;"> arguments used to validate</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * </span><span style="color:#C678DD;font-style:italic;">@throws</span><span style="color:#E5C07B;font-style:italic;"> UDFArgumentNotValidException</span><span style="color:#7F848E;font-style:italic;"> if any parameter is not valid</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * </span><span style="color:#C678DD;font-style:italic;">@return</span><span style="color:#7F848E;font-style:italic;"> the analysis result of the scalar function</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> */</span></span>
<span class="line"><span style="color:#E5C07B;"> ScalarFunctionAnalysis</span><span style="color:#61AFEF;"> analyze</span><span style="color:#ABB2BF;">(</span><span style="color:#E5C07B;">FunctionArguments</span><span style="color:#E06C75;font-style:italic;"> arguments</span><span style="color:#ABB2BF;">)</span><span style="color:#C678DD;"> throws</span><span style="color:#E5C07B;"> UDFArgumentNotValidException</span><span style="color:#ABB2BF;">;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> /**</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * This method is called after the ScalarFunction is instantiated and before the beginning of the</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * transformation process. This method is mainly used to initialize the resources used in</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * ScalarFunction.</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> *</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * </span><span style="color:#C678DD;font-style:italic;">@param</span><span style="color:#E06C75;font-style:italic;"> arguments</span><span style="color:#7F848E;font-style:italic;"> used to parse the input arguments entered by the user</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * </span><span style="color:#C678DD;font-style:italic;">@throws</span><span style="color:#E5C07B;font-style:italic;"> UDFException</span><span style="color:#7F848E;font-style:italic;"> the user can throw errors if necessary</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> */</span></span>
<span class="line"><span style="color:#C678DD;"> default</span><span style="color:#C678DD;"> void</span><span style="color:#61AFEF;"> beforeStart</span><span style="color:#ABB2BF;">(</span><span style="color:#E5C07B;">FunctionArguments</span><span style="color:#E06C75;font-style:italic;"> arguments</span><span style="color:#ABB2BF;">)</span><span style="color:#C678DD;"> throws</span><span style="color:#E5C07B;"> UDFException</span><span style="color:#ABB2BF;"> {</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> // do nothing</span></span>
<span class="line"><span style="color:#ABB2BF;"> }</span></span>
<span class="line"></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> /**</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * This method will be called to process the transformation. In a single UDF query, this method</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * may be called multiple times.</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> *</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * </span><span style="color:#C678DD;font-style:italic;">@param</span><span style="color:#E06C75;font-style:italic;"> input</span><span style="color:#7F848E;font-style:italic;"> original input data row</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * </span><span style="color:#C678DD;font-style:italic;">@throws</span><span style="color:#E5C07B;font-style:italic;"> UDFException</span><span style="color:#7F848E;font-style:italic;"> the user can throw errors if necessary</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> */</span></span>
<span class="line"><span style="color:#E5C07B;"> Object</span><span style="color:#61AFEF;"> evaluate</span><span style="color:#ABB2BF;">(</span><span style="color:#E5C07B;">Record</span><span style="color:#E06C75;font-style:italic;"> input</span><span style="color:#ABB2BF;">)</span><span style="color:#C678DD;"> throws</span><span style="color:#E5C07B;"> UDFException</span><span style="color:#ABB2BF;">;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> /** This method is mainly used to release the resources used in the ScalarFunction. */</span></span>
<span class="line"><span style="color:#C678DD;"> default</span><span style="color:#C678DD;"> void</span><span style="color:#61AFEF;"> beforeDestroy</span><span style="color:#ABB2BF;">()</span><span style="color:#ABB2BF;"> {</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> // do nothing</span></span>
<span class="line"><span style="color:#ABB2BF;"> }</span></span>
<span class="line"><span style="color:#ABB2BF;">}</span></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><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 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 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>接口说明：</p><table><thead><tr><th>接口定义</th><th>描述</th><th>是否必须</th></tr></thead><tbody><tr><td><code>ScalarFunctionAnalysis analyze(FunctionArguments arguments);</code></td><td>1. 校验<code>FunctionArguments</code>中的输入列数、数据类型、系统参数等是否合法，不合法则抛出异常。<br> 2. 根据<code>FunctionArguments</code>构造<code>ScalarFunctionAnalysis</code>，包括输出类型等信息。</td><td>是</td></tr><tr><td><code>void beforeStart(FunctionArguments arguments);</code></td><td>在 UDSF 处理输入数据前，调用用户自定义的初始化行为</td><td>否</td></tr><tr><td><code>Object evaluate(Record input) throws UDFException;</code></td><td>UDSF 处理逻辑，根据一行输入数据，返回一行输出数据。</td><td>是</td></tr><tr><td><code>void beforeDestroy();</code></td><td>UDSF 的结束方法，您可以在此方法中进行一些资源释放等的操作。此方法由框架调用。对于一个实例而言，生命周期中会且只会被调用一次，即在处理完最后一条记录之后被调用。</td><td>否</td></tr></tbody></table><p>目前 ScalarFunctionAnalysis 中的字段：</p><table><thead><tr><th>字段类型</th><th>字段名称</th><th>默认值</th></tr></thead><tbody><tr><td>Type</td><td>outputDataType</td><td>无</td></tr></tbody></table><p>示例：<a href="https://github.com/apache/iotdb/blob/master/example/udf/src/main/java/org/apache/iotdb/udf/ScalarFunctionExample.java" target="_blank" rel="noopener noreferrer">UDSF 的实现示例</a>，输入任意数据类型的任意多列，返回一个布尔值，代表该行输入是否包含 NULL 值。</p><h3 id="_3-3-聚合函数-udaf" tabindex="-1"><a class="header-anchor" href="#_3-3-聚合函数-udaf"><span>3.3 聚合函数（UDAF）</span></a></h3><p>一个完整的 UDAF 定义涉及到 <code>State</code> 和 <code>AggregateFunction</code> 两个类。</p><h4 id="_3-3-1-state-类" tabindex="-1"><a class="header-anchor" href="#_3-3-1-state-类"><span>3.3.1 State 类</span></a></h4><p>编写一个 State 类需要实现<code>org.apache.iotdb.udf.api.State</code>接口。</p><div class="language-c++ line-numbers-mode" data-highlighter="shiki" data-ext="c++" style="background-color:#282c34;color:#abb2bf;"><pre class="shiki one-dark-pro vp-code"><code class="language-c++"><span class="line"><span style="color:#ABB2BF;">public interface State {</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> /** Reset your state object to its initial state. */</span></span>
<span class="line"><span style="color:#C678DD;"> void</span><span style="color:#61AFEF;"> reset</span><span style="color:#ABB2BF;">();</span></span>
<span class="line"></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> /**</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * Serialize your state into byte array. The order of serialization must be consistent with</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * deserialization.</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> */</span></span>
<span class="line"><span style="color:#ABB2BF;"> byte[] </span><span style="color:#61AFEF;">serialize</span><span style="color:#ABB2BF;">();</span></span>
<span class="line"></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> /**</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * Deserialize byte array into your state. The order of deserialization must be consistent with</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * serialization.</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> */</span></span>
<span class="line"><span style="color:#C678DD;"> void</span><span style="color:#61AFEF;"> deserialize</span><span style="color:#ABB2BF;">(byte[] bytes);</span></span>
<span class="line"></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> /** Destroy state. You may release previously binding resource in this method. */</span></span>
<span class="line"><span style="color:#C678DD;"> default</span><span style="color:#C678DD;"> void</span><span style="color:#61AFEF;"> destroyState</span><span style="color:#ABB2BF;">() {}</span></span>
<span class="line"><span style="color:#ABB2BF;"> ;</span></span>
<span class="line"><span style="color:#ABB2BF;">}</span></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><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 class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><p>接口说明：</p><table><thead><tr><th>接口定义</th><th>描述</th><th>是否必须</th></tr></thead><tbody><tr><td><code>void reset() </code></td><td>将<code>State</code>对象重置为初始的状态，您需要像编写构造函数一样，在该方法内填入<code>State</code>类中各个字段的初始值。</td><td>是</td></tr><tr><td><code>byte[] serialize()</code></td><td>将<code>State</code>序列化为二进制数据。该方法用于 IoTDB 内部的<code>State</code>对象传递，注意序列化的顺序必须和下面的反序列化方法一致。</td><td>是</td></tr><tr><td><code>void deserialize(byte[] bytes)</code></td><td>将二进制数据反序列化为<code>State</code>。该方法用于 IoTDB 内部的<code>State</code>对象传递，注意反序列化的顺序必须和上面的序列化方法一致。</td><td>是</td></tr><tr><td><code>void destroyState()</code></td><td>进行资源释放等的操作。此方法由框架调用。对于一个实例而言，生命周期中会且只会被调用一次。</td><td>否</td></tr></tbody></table><h4 id="_3-3-2-aggregatefunction-类" tabindex="-1"><a class="header-anchor" href="#_3-3-2-aggregatefunction-类"><span>3.3.2 AggregateFunction 类</span></a></h4><p>编写一个 UDAF 需要实现 <code>org.apache.iotdb.udf.api.relational.AggregateFunction</code>接口。</p><div class="language-java line-numbers-mode" data-highlighter="shiki" data-ext="java" style="background-color:#282c34;color:#abb2bf;"><pre class="shiki one-dark-pro vp-code"><code class="language-java"><span class="line"><span style="color:#C678DD;">public</span><span style="color:#C678DD;"> interface</span><span style="color:#E5C07B;"> AggregateFunction</span><span style="color:#C678DD;"> extends</span><span style="color:#E5C07B;"> SQLFunction</span><span style="color:#ABB2BF;"> {</span></span>
<span class="line"></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> /**</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * In this method, the user need to do the following things:</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> *</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * &lt;ul&gt;</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * &lt;li&gt;Validate {@linkplain FunctionArguments}. Throw {@link UDFArgumentNotValidException} if</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * any parameter is not valid.</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * &lt;li&gt;Use {@linkplain FunctionArguments} to get input data types and infer output data type.</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * &lt;li&gt;Construct and return a {@linkplain AggregateFunctionAnalysis} object.</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * &lt;/ul&gt;</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> *</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * </span><span style="color:#C678DD;font-style:italic;">@param</span><span style="color:#E06C75;font-style:italic;"> arguments</span><span style="color:#7F848E;font-style:italic;"> arguments used to validate</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * </span><span style="color:#C678DD;font-style:italic;">@throws</span><span style="color:#E5C07B;font-style:italic;"> UDFArgumentNotValidException</span><span style="color:#7F848E;font-style:italic;"> if any parameter is not valid</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * </span><span style="color:#C678DD;font-style:italic;">@return</span><span style="color:#7F848E;font-style:italic;"> the analysis result of the scalar function</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> */</span></span>
<span class="line"><span style="color:#E5C07B;"> AggregateFunctionAnalysis</span><span style="color:#61AFEF;"> analyze</span><span style="color:#ABB2BF;">(</span><span style="color:#E5C07B;">FunctionArguments</span><span style="color:#E06C75;font-style:italic;"> arguments</span><span style="color:#ABB2BF;">)</span></span>
<span class="line"><span style="color:#C678DD;"> throws</span><span style="color:#E5C07B;"> UDFArgumentNotValidException</span><span style="color:#ABB2BF;">;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> /**</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * This method is called after the AggregateFunction is instantiated and before the beginning of</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * the transformation process. This method is mainly used to initialize the resources used in</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * AggregateFunction.</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> *</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * </span><span style="color:#C678DD;font-style:italic;">@param</span><span style="color:#E06C75;font-style:italic;"> arguments</span><span style="color:#7F848E;font-style:italic;"> used to parse the input arguments entered by the user</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * </span><span style="color:#C678DD;font-style:italic;">@throws</span><span style="color:#E5C07B;font-style:italic;"> UDFException</span><span style="color:#7F848E;font-style:italic;"> the user can throw errors if necessary</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> */</span></span>
<span class="line"><span style="color:#C678DD;"> default</span><span style="color:#C678DD;"> void</span><span style="color:#61AFEF;"> beforeStart</span><span style="color:#ABB2BF;">(</span><span style="color:#E5C07B;">FunctionArguments</span><span style="color:#E06C75;font-style:italic;"> arguments</span><span style="color:#ABB2BF;">)</span><span style="color:#C678DD;"> throws</span><span style="color:#E5C07B;"> UDFException</span><span style="color:#ABB2BF;"> {</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> // do nothing</span></span>
<span class="line"><span style="color:#ABB2BF;"> }</span></span>
<span class="line"></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> /** Create and initialize state. You may bind some resource in this method. */</span></span>
<span class="line"><span style="color:#E5C07B;"> State</span><span style="color:#61AFEF;"> createState</span><span style="color:#ABB2BF;">();</span></span>
<span class="line"></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> /**</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * Update state with data columns.</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> *</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * </span><span style="color:#C678DD;font-style:italic;">@param</span><span style="color:#E06C75;font-style:italic;"> state</span><span style="color:#7F848E;font-style:italic;"> state to be updated</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * </span><span style="color:#C678DD;font-style:italic;">@param</span><span style="color:#E06C75;font-style:italic;"> input</span><span style="color:#7F848E;font-style:italic;"> original input data row</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> */</span></span>
<span class="line"><span style="color:#C678DD;"> void</span><span style="color:#61AFEF;"> addInput</span><span style="color:#ABB2BF;">(</span><span style="color:#E5C07B;">State</span><span style="color:#E06C75;font-style:italic;"> state</span><span style="color:#ABB2BF;">, </span><span style="color:#E5C07B;">Record</span><span style="color:#E06C75;font-style:italic;"> input</span><span style="color:#ABB2BF;">);</span></span>
<span class="line"></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> /**</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * Merge two state in execution engine.</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> *</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * </span><span style="color:#C678DD;font-style:italic;">@param</span><span style="color:#E06C75;font-style:italic;"> state</span><span style="color:#7F848E;font-style:italic;"> current state</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * </span><span style="color:#C678DD;font-style:italic;">@param</span><span style="color:#E06C75;font-style:italic;"> rhs</span><span style="color:#7F848E;font-style:italic;"> right-hand-side state to be merged</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> */</span></span>
<span class="line"><span style="color:#C678DD;"> void</span><span style="color:#61AFEF;"> combineState</span><span style="color:#ABB2BF;">(</span><span style="color:#E5C07B;">State</span><span style="color:#E06C75;font-style:italic;"> state</span><span style="color:#ABB2BF;">, </span><span style="color:#E5C07B;">State</span><span style="color:#E06C75;font-style:italic;"> rhs</span><span style="color:#ABB2BF;">);</span></span>
<span class="line"></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> /**</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * Calculate output value from final state</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> *</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * </span><span style="color:#C678DD;font-style:italic;">@param</span><span style="color:#E06C75;font-style:italic;"> state</span><span style="color:#7F848E;font-style:italic;"> final state</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * </span><span style="color:#C678DD;font-style:italic;">@param</span><span style="color:#E06C75;font-style:italic;"> resultValue</span><span style="color:#7F848E;font-style:italic;"> used to collect output data points</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> */</span></span>
<span class="line"><span style="color:#C678DD;"> void</span><span style="color:#61AFEF;"> outputFinal</span><span style="color:#ABB2BF;">(</span><span style="color:#E5C07B;">State</span><span style="color:#E06C75;font-style:italic;"> state</span><span style="color:#ABB2BF;">, </span><span style="color:#E5C07B;">ResultValue</span><span style="color:#E06C75;font-style:italic;"> resultValue</span><span style="color:#ABB2BF;">);</span></span>
<span class="line"></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> /**</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * Remove input data from state. This method is used to remove the data points that have been</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * added to the state. Once it is implemented, {@linkplain</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * AggregateFunctionAnalysis.Builder#removable(boolean)} should be set to true.</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> *</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * </span><span style="color:#C678DD;font-style:italic;">@param</span><span style="color:#E06C75;font-style:italic;"> state</span><span style="color:#7F848E;font-style:italic;"> state to be updated</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> * </span><span style="color:#C678DD;font-style:italic;">@param</span><span style="color:#E06C75;font-style:italic;"> input</span><span style="color:#7F848E;font-style:italic;"> row to be removed</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> */</span></span>
<span class="line"><span style="color:#C678DD;"> default</span><span style="color:#C678DD;"> void</span><span style="color:#61AFEF;"> remove</span><span style="color:#ABB2BF;">(</span><span style="color:#E5C07B;">State</span><span style="color:#E06C75;font-style:italic;"> state</span><span style="color:#ABB2BF;">, </span><span style="color:#E5C07B;">Record</span><span style="color:#E06C75;font-style:italic;"> input</span><span style="color:#ABB2BF;">)</span><span style="color:#ABB2BF;"> {</span></span>
<span class="line"><span style="color:#C678DD;"> throw</span><span style="color:#C678DD;"> new</span><span style="color:#61AFEF;"> UnsupportedOperationException</span><span style="color:#ABB2BF;">();</span></span>
<span class="line"><span style="color:#ABB2BF;"> }</span></span>
<span class="line"></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> /** This method is mainly used to release the resources used in the SQLFunction. */</span></span>
<span class="line"><span style="color:#C678DD;"> default</span><span style="color:#C678DD;"> void</span><span style="color:#61AFEF;"> beforeDestroy</span><span style="color:#ABB2BF;">()</span><span style="color:#ABB2BF;"> {</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;"> // do nothing</span></span>
<span class="line"><span style="color:#ABB2BF;"> }</span></span>
<span class="line"><span style="color:#ABB2BF;">}</span></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><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 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 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 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 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>接口说明：</p><table><thead><tr><th>接口定义</th><th>描述</th><th>是否必须</th></tr></thead><tbody><tr><td><code>AggregateFunctionAnalysis analyze(FunctionArguments arguments);</code></td><td>1. 校验<code>FunctionArguments</code>中的输入列数、数据类型、系统参数等是否合法，不合法则抛出异常。<br> 2. 根据<code>FunctionArguments</code>构造<code>AggregateFunctionAnalysis</code>，包括输出类型、removable 等信息。</td><td>是</td></tr><tr><td><code>void beforeStart(FunctionArguments arguments); </code></td><td>在 UDAF 处理输入数据前，调用用户自定义的初始化行为</td><td>否</td></tr><tr><td><code>State createState();</code></td><td>创建<code>State</code>对象，一般只需要调用默认构造函数，然后按需修改默认的初始值即可。</td><td>是</td></tr><tr><td><code>void addInput(State state, Record input);</code></td><td>更新<code>State</code>对象，将输入的一行<em>​ ​</em><code>Record</code>数据添加到聚合状态中。</td><td>是</td></tr><tr><td><code>void combineState(State state, State rhs); </code></td><td>将<code>rhs</code>状态合并至<code>state</code>状态中。在分布式场景下，同一组的数据可能分布在不同节点上，IoTDB 会为每个节点上的部分数据生成一个<code>State</code>对象，然后调用该方法合并成完整的<code>State</code>。</td><td>是</td></tr><tr><td><code>void outputFinal(State state, ResultValue resultValue);</code></td><td>根据<code>State</code>中的数据，计算出最终的聚合结果。注意根据聚合的语义，每一组只能输出一个值。</td><td>是</td></tr><tr><td><code>void remove(State state, Record input);</code></td><td>更新<code>State</code>对象，将输入的一行<em>​ ​</em><code>Record</code>数据从聚合状态中剔除。<strong>实现该方法需要设置 AggregateFunctionAnalysis 中的 removable 字段为 true。</strong></td><td>否</td></tr><tr><td><code>void beforeDestroy();</code></td><td>UDSF 的结束方法，您可以在此方法中进行一些资源释放等的操作。此方法由框架调用。对于一个实例而言，生命周期中会且只会被调用一次，即在处理完最后一条记录之后被调用。</td><td>否</td></tr></tbody></table><p>目前 AggregateFunctionAnalysis 中的字段：</p><table><thead><tr><th>字段类型</th><th>字段名称</th><th>默认值</th></tr></thead><tbody><tr><td>Type</td><td>outputDataType</td><td>无</td></tr><tr><td>boolean</td><td>removable</td><td>false</td></tr></tbody></table><p>示例：<a href="https://github.com/apache/iotdb/blob/master/example/udf/src/main/java/org/apache/iotdb/udf/AggregateFunctionExample.java" target="_blank" rel="noopener noreferrer">UDAF 的实现示例</a>，计算不为 NULL 的行数。</p><h3 id="_3-4-表函数-udtf" tabindex="-1"><a class="header-anchor" href="#_3-4-表函数-udtf"><span>3.4 表函数（UDTF）</span></a></h3><h4 id="_3-4-1-定义" tabindex="-1"><a class="header-anchor" href="#_3-4-1-定义"><span>3.4.1 定义</span></a></h4><p>表函数，也被称为表值函数（Table-Valued Function，TVF），不同于标量函数、聚合函数和窗口函数的返回值是一个“标量值”，表函数的返回值是一个“表”（结果集）。</p><h4 id="_3-4-2-使用" tabindex="-1"><a class="header-anchor" href="#_3-4-2-使用"><span>3.4.2 使用</span></a></h4><p>表函数可以像关系表一样，以<code>tableFunctionCall</code>的形式在 SQL 查询的 <code>FROM</code> 子句中使用，支持传递参数，并根据参数动态生成结果集。</p><h4 id="_3-4-3-语法" tabindex="-1"><a class="header-anchor" href="#_3-4-3-语法"><span>3.4.3 语法</span></a></h4><p><code>tableFunctionCall</code> 的具体定义如下所示：</p><div class="language-sql line-numbers-mode" data-highlighter="shiki" data-ext="sql" style="background-color:#282c34;color:#abb2bf;"><pre class="shiki one-dark-pro vp-code"><code class="language-sql"><span class="line"><span style="color:#ABB2BF;">tableFunctionCall</span></span>
<span class="line"><span style="color:#ABB2BF;"> : qualifiedName </span><span style="color:#98C379;">&#39;(&#39;</span><span style="color:#ABB2BF;"> (tableFunctionArgument (</span><span style="color:#98C379;">&#39;,&#39;</span><span style="color:#ABB2BF;"> tableFunctionArgument)*)?</span><span style="color:#98C379;">&#39;)&#39;</span></span>
<span class="line"><span style="color:#ABB2BF;"> ;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#ABB2BF;">tableFunctionArgument</span></span>
<span class="line"><span style="color:#ABB2BF;"> : (identifier </span><span style="color:#98C379;">&#39;=&gt;&#39;</span><span style="color:#ABB2BF;">)? (tableArgument | scalarArgument)</span></span>
<span class="line"><span style="color:#ABB2BF;">​ ​;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#ABB2BF;">tableArgument</span></span>
<span class="line"><span style="color:#ABB2BF;"> : tableArgumentRelation</span></span>
<span class="line"><span style="color:#ABB2BF;"> (</span><span style="color:#C678DD;">PARTITION</span><span style="color:#C678DD;"> BY</span><span style="color:#ABB2BF;"> (</span><span style="color:#98C379;">&#39;(&#39;</span><span style="color:#ABB2BF;"> (expression (</span><span style="color:#98C379;">&#39;,&#39;</span><span style="color:#ABB2BF;"> expression)*)? </span><span style="color:#98C379;">&#39;)&#39;</span><span style="color:#ABB2BF;"> | expression))?</span></span>
<span class="line"><span style="color:#ABB2BF;"> (</span><span style="color:#C678DD;">ORDER BY</span><span style="color:#ABB2BF;"> (</span><span style="color:#98C379;">&#39;(&#39;</span><span style="color:#ABB2BF;"> sortItem (</span><span style="color:#98C379;">&#39;,&#39;</span><span style="color:#ABB2BF;"> sortItem)* </span><span style="color:#98C379;">&#39;)&#39;</span><span style="color:#ABB2BF;"> | sortItem))?</span></span>
<span class="line"><span style="color:#ABB2BF;"> ;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#ABB2BF;">tableArgumentRelation</span></span>
<span class="line"><span style="color:#ABB2BF;"> : qualifiedName (</span><span style="color:#C678DD;">AS</span><span style="color:#ABB2BF;">? identifier columnAliases?)? #tableArgumentTable</span></span>
<span class="line"><span style="color:#ABB2BF;"> | </span><span style="color:#98C379;">&#39;(&#39;</span><span style="color:#ABB2BF;"> query </span><span style="color:#98C379;">&#39;)&#39;</span><span style="color:#ABB2BF;"> (</span><span style="color:#C678DD;">AS</span><span style="color:#ABB2BF;">? identifier columnAliases?)? #tableArgumentQuery</span></span>
<span class="line"><span style="color:#ABB2BF;"> ;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#ABB2BF;">scalarArgument</span></span>
<span class="line"><span style="color:#ABB2BF;"> : expression</span></span>
<span class="line"><span style="color:#ABB2BF;"> | timeDuration</span></span>
<span class="line"><span style="color:#ABB2BF;"> ;</span></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><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 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>例如：</p><div class="language-sql line-numbers-mode" data-highlighter="shiki" data-ext="sql" style="background-color:#282c34;color:#abb2bf;"><pre class="shiki one-dark-pro vp-code"><code class="language-sql"><span class="line"><span style="color:#ABB2BF;">// 这是从表函数中进行查询，传入一个字符串“t1”参数。</span></span>
<span class="line"><span style="color:#C678DD;">select</span><span style="color:#ABB2BF;"> * </span><span style="color:#C678DD;">from</span><span style="color:#ABB2BF;"> tvf(</span><span style="color:#98C379;">&#39;t1&#39;</span><span style="color:#ABB2BF;">); </span></span>
<span class="line"></span>
<span class="line"><span style="color:#ABB2BF;">// 这是从表函数中进行查询，传入一个字符串“t1”参数，一个 bid 表参数。</span></span>
<span class="line"><span style="color:#C678DD;">select</span><span style="color:#ABB2BF;"> * </span><span style="color:#C678DD;">from</span><span style="color:#ABB2BF;"> tvf(</span><span style="color:#98C379;">&#39;t1&#39;</span><span style="color:#ABB2BF;">, bid);</span></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><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><h4 id="_3-4-4-函数参数" tabindex="-1"><a class="header-anchor" href="#_3-4-4-函数参数"><span>3.4.4 函数参数</span></a></h4><p>IoTDB 中的表函数为多态表值函数，支持参数类型如下所示：</p><table><thead><tr><th>参数类型</th><th>定义</th><th>示例</th></tr></thead><tbody><tr><td>标量参数（Scalar Argument）</td><td>必须是常量表达式，可以是任何的 SQL 数据类型，需要和声明的类型兼容。</td><td><code>SIZE =&gt; 42</code>，<code>SIZE =&gt; &#39;42&#39;</code>，<code>SIZE =&gt; 42.2</code>，<code>SIZE =&gt; 12h</code>，<code>SIZE =&gt; 60m</code></td></tr><tr><td>表参数（Table Argument）</td><td>可以是一个表名或一条查询语句。</td><td><code>input =&gt; orders</code>，<code>data =&gt; (SELECT * FROM region, nation WHERE region.regionkey = nation.regionkey)</code></td></tr></tbody></table><p>表参数具有如下属性：</p><ol><li><p>组语义与行语义</p><ul><li><p>被声明为组语义（Set Semantic）的表参数意味着需要根据整个完整的分区才能得到结果集。</p><ul><li>允许在调用时指定 PARTITION 或 ORDER，执行引擎会 partition-by-partition 地进行处理。</li></ul><div class="language-sql line-numbers-mode" data-highlighter="shiki" data-ext="sql" style="background-color:#282c34;color:#abb2bf;"><pre class="shiki one-dark-pro vp-code"><code class="language-sql"><span class="line"><span style="color:#ABB2BF;">input </span><span style="color:#56B6C2;">=&gt;</span><span style="color:#ABB2BF;"> orders </span><span style="color:#C678DD;">PARTITION</span><span style="color:#C678DD;"> BY</span><span style="color:#ABB2BF;"> device_id </span><span style="color:#C678DD;">ORDER BY</span><span style="color:#C678DD;"> time</span></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div></div></div><ul><li>如果没有指定 PARTITION，则认为所有的数据都在同一个数据组中。</li></ul></li><li><p>被声明为行语义（Row Semantics）的表参数意味着行与行之间没有依赖关系。不允许在调用时指定 PARTITION 或 ORDER，执行引擎会 row-by-row 地进行处理。</p></li></ul></li><li><p>列穿透（Pass-through Columns）</p><ul><li>表参数如果被声明为列穿透，则表函数的结果列会包含该表参数输入的所有列。</li><li>例如，窗口分析函数，通过为表参数设置列穿透属性，可实现输出结果为“所有输入列（包含原始列和聚合结果）+窗口ID”，即“原始数据+分析结果”。</li></ul></li></ol><h4 id="_3-4-5-传递方式" tabindex="-1"><a class="header-anchor" href="#_3-4-5-传递方式"><span>3.4.5 传递方式</span></a></h4><table><thead><tr><th>传递方式</th><th>描述</th><th>示例</th></tr></thead><tbody><tr><td>按名传递</td><td>1. 可以通过任意的顺序传递参数。<br>2. 被声明有默认值的参数可以被省略。<br>3. 参数名大小写不敏感。</td><td><code>SELECT * FROM my_function(row_count =&gt; 100, column_count =&gt; 1);</code> <code>SELECT * FROM my_function(column_count =&gt; 1, row_count =&gt; 100);</code> <code>SELECT * FROM my_function(column_count =&gt; 1);</code></td></tr><tr><td>按位置传递</td><td>1. 必须按照声明的顺序进行传递参数。<br>2. 如果余下的参数都有默认值，可以只传一部分参数。</td><td><code>SELECT * FROM my_function(1, 100);</code> <code>SELECT * FROM my_function(1);</code></td></tr></tbody></table><blockquote><p>注意：<br> 以上两种方式不允许混用，否则在语义解析时候会抛出“​<strong>All arguments must be passed by name or all must be passed positionally</strong>​”异常。</p></blockquote><h4 id="_3-4-6-返回结果" tabindex="-1"><a class="header-anchor" href="#_3-4-6-返回结果"><span>3.4.6 返回结果</span></a></h4><p>表函数的结果集由以下两部分组成。</p><ol><li>由表函数创建的生成列（Proper Columns）。</li><li>根据表参数自动构建的映射列（Pass-through Columns）。 <ul><li>如果指定了表参数的属性为列穿透，则会包括输入关系的所有列；</li><li>如果没有指定为列穿透但指定了 PartitionBy，则是 PartitionBy 的列；</li><li>如果均未指定，则不根据表参数自动构建列。</li></ul></li></ol><h3 id="_3-5-完整maven项目示例" tabindex="-1"><a class="header-anchor" href="#_3-5-完整maven项目示例"><span>3.5 完整Maven项目示例</span></a></h3><p>如果使用 <a href="http://search.maven.org/" target="_blank" rel="noopener noreferrer">Maven</a>，可以参考示例项目<a href="https://github.com/apache/iotdb/tree/master/example/udf" target="_blank" rel="noopener noreferrer">udf-example</a>。</p></div><!----><!----><!----></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/zh/UserGuide/latest-Table/User-Manual/User-defined-function.md" aria-label="发现错误？在 GitHub 上编辑此页" 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><!--]-->发现错误？在 GitHub 上编辑此页<!----></a></div><div class="vp-meta-item git-info"><div class="update-time"><span class="vp-meta-label">最近更新: </span><time class="vp-meta-info" datetime="2025-12-26T03:14:31.000Z" data-allow-mismatch>2025/12/26 03:14</time></div><!----></div></footer><nav class="vp-page-nav"><a class="route-link auto-link prev" href="/zh/UserGuide/latest-Table/User-Manual/Data-Sync_apache.html" aria-label="数据同步"><div class="hint"><span class="arrow start"></span>上一页</div><div class="link"><!---->数据同步</div></a><!----></nav><!----><!----><!--]--></main><!--]--><footer class="site-footer"><span id="doc-version" style="display:none;">latest-Table</span><p class="copyright-text">版权所有 © 2026 Apache软件基金会。
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