assets/js/519.e6ce35ef.js

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"),s("td",[t._v("自定义时间序列生成函数。该类函数允许接收多条时间序列，最终会输出一条时间序列，生成的时间序列可以有任意多数量的数据点。")])]),t._v(" "),s("tr",[s("td",[t._v("UDAF（User Defined Aggregation Function）")]),t._v(" "),s("td",[t._v("正在开发，敬请期待。")])])])]),t._v(" "),s("h2",{attrs:{id:"udf-依赖"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#udf-依赖"}},[t._v("#")]),t._v(" UDF 依赖")]),t._v(" "),s("p",[t._v("如果您使用 "),s("a",{attrs:{href:"http://search.maven.org/",target:"_blank",rel:"noopener noreferrer"}},[t._v("Maven"),s("OutboundLink")],1),t._v("，可以从 "),s("a",{attrs:{href:"http://search.maven.org/",target:"_blank",rel:"noopener noreferrer"}},[t._v("Maven 库"),s("OutboundLink")],1),t._v(" 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。")]),t._v(" "),s("div",{staticClass:"language-xml line-numbers-mode"},[s("pre",{pre:!0,attrs:{class:"language-xml"}},[s("code",[s("span",{pre:!0,attrs:{class:"token tag"}},[s("span",{pre:!0,attrs:{class:"token tag"}},[s("span",{pre:!0,attrs:{class:"token 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line-numbers-mode"},[s("pre",{pre:!0,attrs:{class:"language-sql"}},[s("code",[s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("SHOW")]),t._v(" FUNCTIONS\n")])]),t._v(" "),s("div",{staticClass:"line-numbers-wrapper"},[s("span",{staticClass:"line-number"},[t._v("1")]),s("br")])]),s("h2",{attrs:{id:"用户权限管理"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#用户权限管理"}},[t._v("#")]),t._v(" 用户权限管理")]),t._v(" "),s("p",[t._v("用户在使用 UDF 时会涉及到 3 种权限：")]),t._v(" "),s("ul",[s("li",[s("code",[t._v("CREATE_FUNCTION")]),t._v("：具备该权限的用户才被允许执行 UDF 注册操作")]),t._v(" "),s("li",[s("code",[t._v("DROP_FUNCTION")]),t._v("：具备该权限的用户才被允许执行 UDF 卸载操作")]),t._v(" "),s("li",[s("code",[t._v("READ_TIMESERIES")]),t._v("：具备该权限的用户才被允许使用 UDF 进行查询")])]),t._v(" "),s("p",[t._v("更多用户权限相关的内容，请参考 "),s("RouterLink",{attrs:{to:"/zh/UserGuide/Master/Administration-Management/Administration.html"}},[t._v("权限管理语句")]),t._v("。")],1),t._v(" "),s("h2",{attrs:{id:"配置项"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#配置项"}},[t._v("#")]),t._v(" 配置项")]),t._v(" "),s("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"),s("code",[t._v("iotdb-datanode.properties")]),t._v("中的"),s("code",[t._v("udf_initial_byte_array_length_for_memory_control")]),t._v("，"),s("code",[t._v("udf_memory_budget_in_mb")]),t._v("和"),s("code",[t._v("udf_reader_transformer_collector_memory_proportion")]),t._v("并重启服务来解决此问题。")]),t._v(" "),s("h2",{attrs:{id:"贡献-udf"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#贡献-udf"}},[t._v("#")]),t._v(" 贡献 UDF")]),t._v(" "),s("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(" "),s("h3",{attrs:{id:"前提条件"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#前提条件"}},[t._v("#")]),t._v(" 前提条件")]),t._v(" "),s("ol",[s("li",[s("p",[t._v("UDF 具有通用性。")]),t._v(" "),s("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(" "),s("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 "),s("code",[t._v("dev@iotdb.apache.org")]),t._v(" 或直接创建 ISSUE 发起讨论。")])]),t._v(" "),s("li",[s("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(" "),s("h3",{attrs:{id:"贡献清单"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#贡献清单"}},[t._v("#")]),t._v(" 贡献清单")]),t._v(" "),s("ol",[s("li",[t._v("UDF 的源代码")]),t._v(" "),s("li",[t._v("UDF 的测试用例")]),t._v(" "),s("li",[t._v("UDF 的使用说明")])]),t._v(" "),s("h4",{attrs:{id:"源代码"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#源代码"}},[t._v("#")]),t._v(" 源代码")]),t._v(" "),s("ol",[s("li",[t._v("在"),s("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(" "),s("li",[t._v("在"),s("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(" "),s("h4",{attrs:{id:"测试用例"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#测试用例"}},[t._v("#")]),t._v(" 测试用例")]),t._v(" "),s("p",[t._v("您至少需要为您贡献的 UDF 编写集成测试。")]),t._v(" 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