(window.webpackJsonp=window.webpackJsonp||[]).push([[350],{919:function(t,s,a){"use strict";a.r(s);var n=a(69),e=Object(n.a)({},(function(){var t=this,s=t.$createElement,a=t._self._c||s;return a("ContentSlotsDistributor",{attrs:{"slot-key":t.$parent.slotKey}},[a("h1",{attrs:{id:"udf-用户定义函数"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#udf-用户定义函数"}},[t._v("#")]),t._v(" UDF (用户定义函数)")]),t._v(" "),a("p",[t._v("UDF（User Defined Function）即用户自定义函数。IoTDB提供多种内建函数来满足您的计算需求，同时您还可以通过创建自定义函数来满足更多的计算需求。")]),t._v(" "),a("p",[t._v("根据此文档，您将会很快学会UDF的编写、注册、使用等操作。")]),t._v(" "),a("h2",{attrs:{id:"udf分类"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#udf分类"}},[t._v("#")]),t._v(" UDF分类")]),t._v(" "),a("p",[t._v("IoTDB 支持两种类型的 UDF 函数，如下表所示。")]),t._v(" "),a("table",[a("thead",[a("tr",[a("th",[t._v("UDF 分类")]),t._v(" "),a("th",[t._v("描述")])])]),t._v(" "),a("tbody",[a("tr",[a("td",[t._v("UDTF（User Defined Timeseries Generating Function）")]),t._v(" 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"),a("h2",{attrs:{id:"udf卸载"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#udf卸载"}},[t._v("#")]),t._v(" UDF卸载")]),t._v(" "),a("p",[t._v("卸载UDF的SQL语法如下：")]),t._v(" "),a("div",{staticClass:"language-sql line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-sql"}},[a("code",[a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("DROP")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("FUNCTION")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token operator"}},[t._v("<")]),t._v("UDF"),a("span",{pre:!0,attrs:{class:"token operator"}},[t._v("-")]),t._v("NAME"),a("span",{pre:!0,attrs:{class:"token operator"}},[t._v(">")]),t._v("\n")])]),t._v(" "),a("div",{staticClass:"line-numbers-wrapper"},[a("span",{staticClass:"line-number"},[t._v("1")]),a("br")])]),a("p",[t._v("可以通过如下SQL语句卸载上面例子中的UDF：")]),t._v(" "),a("div",{staticClass:"language-sql line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-sql"}},[a("code",[a("span",{pre:!0,attrs:{class:"token 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"),a("p",[t._v("假定现在有时间序列 "),a("code",[t._v("root.sg.d1.s1")]),t._v("和 "),a("code",[t._v("root.sg.d1.s2")]),t._v("。")]),t._v(" "),a("ul",[a("li",[a("strong",[t._v("执行"),a("code",[t._v("SELECT example(*) from root.sg.d1")])])])]),t._v(" "),a("p",[t._v("那么结果集中将包括"),a("code",[t._v("example(root.sg.d1.s1)")]),t._v("和"),a("code",[t._v("example(root.sg.d1.s2)")]),t._v("的结果。")]),t._v(" "),a("ul",[a("li",[a("strong",[t._v("执行"),a("code",[t._v("SELECT example(s1, *) from root.sg.d1")])])])]),t._v(" "),a("p",[t._v("那么结果集中将包括"),a("code",[t._v("example(root.sg.d1.s1, root.sg.d1.s1)")]),t._v("和"),a("code",[t._v("example(root.sg.d1.s1, root.sg.d1.s2)")]),t._v("的结果。")]),t._v(" "),a("ul",[a("li",[a("strong",[t._v("执行"),a("code",[t._v("SELECT example(*, *) from root.sg.d1")])])])]),t._v(" "),a("p",[t._v("那么结果集中将包括"),a("code",[t._v("example(root.sg.d1.s1, root.sg.d1.s1)")]),t._v("，"),a("code",[t._v("example(root.sg.d1.s2, root.sg.d1.s1)")]),t._v("，"),a("code",[t._v("example(root.sg.d1.s1, root.sg.d1.s2)")]),t._v(" 和 "),a("code",[t._v("example(root.sg.d1.s2, root.sg.d1.s2)")]),t._v("的结果。")]),t._v(" "),a("h3",{attrs:{id:"带自定义输入参数的查询"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#带自定义输入参数的查询"}},[t._v("#")]),t._v(" 带自定义输入参数的查询")]),t._v(" "),a("p",[t._v("您可以在进行UDF查询的时候，向UDF传入任意数量的键值对参数。键值对中的键和值都需要被单引号或者双引号引起来。注意，键值对参数只能在所有时间序列后传入。下面是一组例子：")]),t._v(" "),a("div",{staticClass:"language-sql line-numbers-mode"},[a("pre",{pre:!0,attrs:{class:"language-sql"}},[a("code",[a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("SELECT")]),t._v(" example"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),t._v("s1"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(",")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token string"}},[t._v('"key1"')]),a("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),a("span",{pre:!0,attrs:{class:"token string"}},[t._v('"value1"')]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(",")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token string"}},[t._v('"key2"')]),a("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),a("span",{pre:!0,attrs:{class:"token string"}},[t._v('"value2"')]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(",")]),t._v(" example"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),a("span",{pre:!0,attrs:{class:"token operator"}},[t._v("*")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(",")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token string"}},[t._v('"key3"')]),a("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),a("span",{pre:!0,attrs:{class:"token string"}},[t._v('"value3"')]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("FROM")]),t._v(" root"),a("span",{pre:!0,attrs:{class:"token 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"),a("p",[t._v("在SQL语句中使用自定义函数时，可能提示内存不足。这种情况下，您可以通过更改配置文件"),a("code",[t._v("iotdb-engine.properties")]),t._v("中的"),a("code",[t._v("udf_initial_byte_array_length_for_memory_control")]),t._v("，"),a("code",[t._v("udf_memory_budget_in_mb")]),t._v("和"),a("code",[t._v("udf_reader_transformer_collector_memory_proportion")]),t._v("并重启服务来解决此问题。")]),t._v(" "),a("h2",{attrs:{id:"贡献udf"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#贡献udf"}},[t._v("#")]),t._v(" 贡献UDF")]),t._v(" "),a("p",[t._v("该部分主要讲述了外部用户如何将自己编写的 UDF 贡献给 IoTDB 社区。")]),t._v(" "),a("h3",{attrs:{id:"前提条件"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#前提条件"}},[t._v("#")]),t._v(" 前提条件")]),t._v(" "),a("ol",[a("li",[a("p",[t._v("UDF 具有通用性。")]),t._v(" "),a("p",[t._v("通用性主要指的是：UDF 在某些业务场景下，可以被广泛使用。换言之，就是 UDF 具有复用价值，可被社区内其他用户直接使用。")]),t._v(" "),a("p",[t._v("如果您不确定自己写的 UDF 是否具有通用性，可以发邮件到 "),a("code",[t._v("dev@iotdb.apache.org")]),t._v(" 或直接创建 ISSUE 发起讨论。")])]),t._v(" "),a("li",[a("p",[t._v("UDF 已经完成测试，且能够正常运行在用户的生产环境中。")])])]),t._v(" "),a("h3",{attrs:{id:"贡献清单"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#贡献清单"}},[t._v("#")]),t._v(" 贡献清单")]),t._v(" "),a("ol",[a("li",[t._v("UDF 的源代码")]),t._v(" "),a("li",[t._v("UDF 的测试用例")]),t._v(" "),a("li",[t._v("UDF 的使用说明")])]),t._v(" "),a("h4",{attrs:{id:"源代码"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#源代码"}},[t._v("#")]),t._v(" 源代码")]),t._v(" "),a("ol",[a("li",[t._v("在"),a("code",[t._v("src/main/java/org/apache/iotdb/db/query/udf/builtin")]),t._v("或者它的子文件夹中创建 UDF 主类和相关的辅助类。")]),t._v(" "),a("li",[t._v("在"),a("code",[t._v("src/main/java/org/apache/iotdb/db/query/udf/builtin/BuiltinFunction.java")]),t._v("中注册您编写的 UDF。")])]),t._v(" "),a("h4",{attrs:{id:"测试用例"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#测试用例"}},[t._v("#")]),t._v(" 测试用例")]),t._v(" "),a("p",[t._v("您至少需要为您贡献的 UDF 编写集成测试。")]),t._v(" "),a("p",[t._v("您可以在"),a("code",[t._v("server/src/test/java/org/apache/iotdb/db/integration")]),t._v("中为您贡献的 UDF 新增一个测试类进行测试。")]),t._v(" "),a("h4",{attrs:{id:"使用说明"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#使用说明"}},[t._v("#")]),t._v(" 使用说明")]),t._v(" "),a("p",[t._v("使用说明需要包含：UDF 的名称、UDF的作用、执行函数必须的属性参数、函数的适用的场景以及使用示例等。")]),t._v(" "),a("p",[t._v("使用说明需包含中英文两个版本。应分别在 "),a("code",[t._v("docs/zh/UserGuide/Operation Manual/DML Data Manipulation Language.md")]),t._v(" 和 "),a("code",[t._v("docs/UserGuide/Operation Manual/DML Data Manipulation Language.md")]),t._v(" 中新增使用说明。")]),t._v(" "),a("h3",{attrs:{id:"提交pr"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#提交pr"}},[t._v("#")]),t._v(" 提交PR")]),t._v(" "),a("p",[t._v("当您准备好源代码、测试用例和使用说明后，就可以将 UDF 贡献到 IoTDB 社区了。在 "),a("a",{attrs:{href:"https://github.com/apache/iotdb",target:"_blank",rel:"noopener noreferrer"}},[t._v("Github"),a("OutboundLink")],1),t._v(" 上面提交 Pull Request (PR) 即可。具体提交方式见："),a("a",{attrs:{href:"https://iotdb.apache.org/Development/HowToCommit.html",target:"_blank",rel:"noopener noreferrer"}},[t._v("Pull Request 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