(window.webpackJsonp=window.webpackJsonp||[]).push([[89],{656:function(t,a,s){"use strict";s.r(a);var e=s(69),n=Object(e.a)({},(function(){var t=this,a=t.$createElement,s=t._self._c||a;return s("ContentSlotsDistributor",{attrs:{"slot-key":t.$parent.slotKey}},[s("h1",{attrs:{id:"udf-user-defined-function"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#udf-user-defined-function"}},[t._v("#")]),t._v(" UDF (User Defined Function)")]),t._v(" "),s("p",[t._v("IoTDB provides a variety of built-in functions to meet your computing needs, and you can also create user defined functions to meet more computing needs.")]),t._v(" "),s("p",[t._v("This document describes how to write, register and use a UDF.")]),t._v(" "),s("h2",{attrs:{id:"udf-types"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#udf-types"}},[t._v("#")]),t._v(" UDF Types")]),t._v(" "),s("p",[t._v("In IoTDB, you can expand two types of UDF:")]),t._v(" "),s("table",[s("thead",[s("tr",[s("th",[t._v("UDF Class")]),t._v(" "),s("th",[t._v("Description")])])]),t._v(" "),s("tbody",[s("tr",[s("td",[t._v("UDTF（User Defined Timeseries Generating Function）")]),t._v(" "),s("td",[t._v("This type of function can take "),s("strong",[t._v("multiple")]),t._v(" time series as input, and output "),s("strong",[t._v("one")]),t._v(" time series, which can have any number of data points.")])]),t._v(" "),s("tr",[s("td",[t._v("UDAF（User Defined Aggregation Function）")]),t._v(" "),s("td",[t._v("Under development, please stay tuned.")])])])]),t._v(" "),s("h2",{attrs:{id:"udf-development-dependencies"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#udf-development-dependencies"}},[t._v("#")]),t._v(" UDF Development Dependencies")]),t._v(" "),s("p",[t._v("If you use "),s("a",{attrs:{href:"http://search.maven.org/",target:"_blank",rel:"noopener noreferrer"}},[t._v("Maven"),s("OutboundLink")],1),t._v(", you can search for the development dependencies listed below from the "),s("a",{attrs:{href:"http://search.maven.org/",target:"_blank",rel:"noopener noreferrer"}},[t._v("Maven repository"),s("OutboundLink")],1),t._v(" . 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You need to call the data collection method provided by "),s("code",[t._v("collector")]),t._v("  to determine the output data.")]),t._v(" "),s("td",[t._v("Required to implement at least one "),s("code",[t._v("transform")]),t._v(" method")])]),t._v(" "),s("tr",[s("td",{staticStyle:{"text-align":"left"}},[s("code",[t._v("void terminate(PointCollector collector) throws Exception")])]),t._v(" "),s("td",{staticStyle:{"text-align":"left"}},[t._v("This method is called by the framework. This method will be called once after all "),s("code",[t._v("transform")]),t._v(" calls have been executed. In a single UDF query, this method will and will only be called once. 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"),s("p",[t._v("Note that the raw data access strategy you set here determines which "),s("code",[t._v("transform")]),t._v(" method the framework will call. Please implement the "),s("code",[t._v("transform")]),t._v(" method corresponding to the raw data access strategy. Of course, you can also dynamically decide which strategy to set based on the attribute parameters parsed by "),s("code",[t._v("UDFParameters")]),t._v(". Therefore, two "),s("code",[t._v("transform")]),t._v(" methods are also allowed to be implemented in one UDF.")]),t._v(" "),s("p",[t._v("The following are the strategies you can set:")]),t._v(" "),s("table",[s("thead",[s("tr",[s("th",{staticStyle:{"text-align":"left"}},[t._v("Interface definition")]),t._v(" "),s("th",{staticStyle:{"text-align":"left"}},[t._v("Description")]),t._v(" "),s("th",[t._v("The "),s("code",[t._v("transform")]),t._v(" Method to Call")])])]),t._v(" "),s("tbody",[s("tr",[s("td",{staticStyle:{"text-align":"left"}},[s("code",[t._v("RowByRowAccessStrategy")])]),t._v(" "),s("td",{staticStyle:{"text-align":"left"}},[t._v("Process raw data row by row. The framework calls the "),s("code",[t._v("transform")]),t._v(" method once for each row of raw data input. When UDF has only one input sequence, a row of input is one data point in the input sequence. When UDF has multiple input sequences, one row of input is a result record of the raw query (aligned by time) on these input sequences. (In a row, there may be a column with a value of "),s("code",[t._v("null")]),t._v(", but not all of them are "),s("code",[t._v("null")]),t._v(")")]),t._v(" "),s("td",[s("code",[t._v("void transform(Row row, PointCollector collector) throws Exception")])])]),t._v(" "),s("tr",[s("td",{staticStyle:{"text-align":"left"}},[s("code",[t._v("SlidingTimeWindowAccessStrategy")])]),t._v(" "),s("td",{staticStyle:{"text-align":"left"}},[t._v("Process a batch of data in a fixed time interval each time. We call the container of a data batch a window. The framework calls the "),s("code",[t._v("transform")]),t._v(" method once for each raw data input window. There may be multiple rows of data in a window, and each row is a result record of the raw query (aligned by time) on these input sequences. (In a row, there may be a column with a value of "),s("code",[t._v("null")]),t._v(", but not all of them are "),s("code",[t._v("null")]),t._v(")")]),t._v(" "),s("td",[s("code",[t._v("void transform(RowWindow rowWindow, PointCollector collector) throws Exception")])])]),t._v(" "),s("tr",[s("td",{staticStyle:{"text-align":"left"}},[s("code",[t._v("SlidingSizeWindowAccessStrategy")])]),t._v(" "),s("td",{staticStyle:{"text-align":"left"}},[t._v("The raw data is processed batch by batch, and each batch contains a fixed number of raw data rows (except the last batch). We call the container of a data batch a window. The framework calls the "),s("code",[t._v("transform")]),t._v(" method once for each raw data input window. There may be multiple rows of data in a window, and each row is a result record of the raw query (aligned by time) on these input sequences. (In a row, there may be a column with a value of "),s("code",[t._v("null")]),t._v(", but not all of them are "),s("code",[t._v("null")]),t._v(")")]),t._v(" "),s("td",[s("code",[t._v("void transform(RowWindow rowWindow, PointCollector collector) throws Exception")])])])])]),t._v(" "),s("p",[s("code",[t._v("RowByRowAccessStrategy")]),t._v(": The construction of "),s("code",[t._v("RowByRowAccessStrategy")]),t._v(" does not require any parameters.")]),t._v(" "),s("p",[s("code",[t._v("SlidingTimeWindowAccessStrategy")]),t._v(": "),s("code",[t._v("SlidingTimeWindowAccessStrategy")]),t._v(" has many constructors, you can pass 3 types of parameters to them:")]),t._v(" "),s("ul",[s("li",[t._v("Parameter 1: The display window on the time axis")]),t._v(" "),s("li",[t._v("Parameter 2: Time interval for dividing the time axis (should be positive)")]),t._v(" "),s("li",[t._v("Parameter 3: Time sliding step (not required to be greater than or equal to the time interval, but must be a positive number)")])]),t._v(" "),s("p",[t._v("The first type of parameters are optional. If the parameters are not provided, the beginning time of the display window will be set to the same as the minimum timestamp of the query result set, and the ending time of the display window will be set to the same as the maximum timestamp of the query result set.")]),t._v(" "),s("p",[t._v("The sliding step parameter is also optional. If the parameter is not provided, the sliding step will be set to the same as the time interval for dividing the time axis.")]),t._v(" "),s("p",[t._v("The relationship between the three types of parameters can be seen in the figure below. Please see the Javadoc for more details.")]),t._v(" "),s("div",{staticStyle:{"text-align":"center"}},[s("img",{staticStyle:{width:"100%","max-width":"800px","max-height":"600px","margin-left":"auto","margin-right":"auto",display:"block"},attrs:{src:"https://user-images.githubusercontent.com/30497621/99787878-47b51480-2b5b-11eb-8ed3-84088c5c30f7.png"}})]),t._v(" "),s("p",[t._v("Note that the actual time interval of some of the last time windows may be less than the specified time interval parameter. In addition, there may be cases where the number of data rows in some time windows is 0. In these cases, the framework will also call the "),s("code",[t._v("transform")]),t._v(" method for the empty windows.")]),t._v(" "),s("p",[s("code",[t._v("SlidingSizeWindowAccessStrategy")]),t._v(":  "),s("code",[t._v("SlidingSizeWindowAccessStrategy")]),t._v(" has many constructors, you can pass 2 types of parameters to them:")]),t._v(" "),s("ul",[s("li",[t._v("Parameter 1: Window size. This parameter specifies the number of data rows contained in a data processing window. Note that the number of data rows in some of the last time windows may be less than the specified number of data rows.")]),t._v(" "),s("li",[t._v("Parameter 2: Sliding step. This parameter means the number of rows between the first point of the next window and the first point of the current window. (This parameter is not required to be greater than or equal to the window size, but must be a positive number)")])]),t._v(" "),s("p",[t._v("The sliding step parameter is optional. If the parameter is not provided, the sliding step will be set to the same as the window size.")]),t._v(" "),s("p",[t._v("Please see the Javadoc for more details.")]),t._v(" "),s("h5",{attrs:{id:"setoutputdatatype"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#setoutputdatatype"}},[t._v("#")]),t._v(" setOutputDataType")]),t._v(" "),s("p",[t._v("Note that the type of output sequence you set here determines the type of data that the "),s("code",[t._v("PointCollector")]),t._v(" can actually receive in the "),s("code",[t._v("transform")]),t._v(" method. The relationship between the output data type set in "),s("code",[t._v("setOutputDataType")]),t._v(" and the actual data output type that "),s("code",[t._v("PointCollector")]),t._v(" can receive is as follows:")]),t._v(" "),s("table",[s("thead",[s("tr",[s("th",{staticStyle:{"text-align":"left"}},[t._v("Output Data Type Set in "),s("code",[t._v("setOutputDataType")])]),t._v(" "),s("th",{staticStyle:{"text-align":"left"}},[t._v("Data Type that "),s("code",[t._v("PointCollector")]),t._v(" Can Receive")])])]),t._v(" "),s("tbody",[s("tr",[s("td",{staticStyle:{"text-align":"left"}},[s("code",[t._v("INT32")])]),t._v(" "),s("td",{staticStyle:{"text-align":"left"}},[s("code",[t._v("int")])])]),t._v(" "),s("tr",[s("td",{staticStyle:{"text-align":"left"}},[s("code",[t._v("INT64")])]),t._v(" "),s("td",{staticStyle:{"text-align":"left"}},[s("code",[t._v("long")])])]),t._v(" "),s("tr",[s("td",{staticStyle:{"text-align":"left"}},[s("code",[t._v("FLOAT")])]),t._v(" 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The raw data is input from "),s("code",[t._v("Row")]),t._v(" and output by "),s("code",[t._v("PointCollector")]),t._v(". You can output any number of data points in one "),s("code",[t._v("transform")]),t._v(" method call. It should be noted that the type of output data points must be the same as you set in the "),s("code",[t._v("beforeStart")]),t._v(" method, and the timestamps of output data points must be strictly monotonically increasing.")]),t._v(" "),s("p",[t._v("The following is a complete UDF example that implements the "),s("code",[t._v("void transform(Row row, PointCollector collector) throws Exception")]),t._v(" method. It is an adder that receives two columns of time series as input. 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If you use Maven to manage your project, you can refer to the Maven project example above.")])]),t._v(" "),s("li",[s("p",[t._v("Place the JAR package in the directory "),s("code",[t._v("iotdb-server-0.12.0-SNAPSHOT/ext/udf")]),t._v(" or in a subdirectory of "),s("code",[t._v("iotdb-server-0.12.0-SNAPSHOT/ext/udf")]),t._v(".")]),t._v(" "),s("blockquote",[s("p",[t._v("You can specify the root path for the UDF to load the Jar by modifying the 'udf_root_dir' in the configuration file.")])])]),t._v(" "),s("li",[s("p",[t._v("Register the UDF with the SQL statement, assuming that the name given to the UDF is "),s("code",[t._v("example")]),t._v(".")])])]),t._v(" "),s("p",[t._v("The following shows the SQL syntax of how to register a UDF.")]),t._v(" "),s("div",{staticClass:"language-sql line-numbers-mode"},[s("pre",{pre:!0,attrs:{class:"language-sql"}},[s("code",[s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("CREATE")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("FUNCTION")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("<")]),t._v("UDF"),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("-")]),t._v("NAME"),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v(">")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("AS")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("<")]),t._v("UDF"),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("-")]),t._v("CLASS"),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("-")]),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("FULL")]),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("-")]),t._v("PATHNAME"),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v(">")]),t._v("\n")])]),t._v(" "),s("div",{staticClass:"line-numbers-wrapper"},[s("span",{staticClass:"line-number"},[t._v("1")]),s("br")])]),s("p",[t._v("Here is an example:")]),t._v(" "),s("div",{staticClass:"language-sql line-numbers-mode"},[s("pre",{pre:!0,attrs:{class:"language-sql"}},[s("code",[s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("CREATE")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("FUNCTION")]),t._v(" example "),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("AS")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token string"}},[t._v('"org.apache.iotdb.udf.ExampleUDTF"')]),t._v("\n")])]),t._v(" "),s("div",{staticClass:"line-numbers-wrapper"},[s("span",{staticClass:"line-number"},[t._v("1")]),s("br")])]),s("p",[t._v("Since UDF instances are dynamically loaded through reflection technology, you do not need to restart the server during the UDF registration process.")]),t._v(" "),s("p",[t._v("Note: UDF function names are not case sensitive.")]),t._v(" "),s("p",[t._v("Note: Please ensure that the function name given to the UDF is different from all built-in function names. 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If you use two UDFs in the same SQL statement at the same time, the system will randomly load either of them and may cause inconsistency in UDF execution behavior.")]),t._v(" "),s("h2",{attrs:{id:"udf-deregistration"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#udf-deregistration"}},[t._v("#")]),t._v(" UDF Deregistration")]),t._v(" "),s("p",[t._v("The following shows the SQL syntax of how to deregister a UDF.")]),t._v(" "),s("div",{staticClass:"language-sql line-numbers-mode"},[s("pre",{pre:!0,attrs:{class:"language-sql"}},[s("code",[s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("DROP")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("FUNCTION")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("<")]),t._v("UDF"),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("-")]),t._v("NAME"),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v(">")]),t._v("\n")])]),t._v(" "),s("div",{staticClass:"line-numbers-wrapper"},[s("span",{staticClass:"line-number"},[t._v("1")]),s("br")])]),s("p",[t._v("Here is an example:")]),t._v(" "),s("div",{staticClass:"language-sql line-numbers-mode"},[s("pre",{pre:!0,attrs:{class:"language-sql"}},[s("code",[s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("DROP")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("FUNCTION")]),t._v(" example\n")])]),t._v(" "),s("div",{staticClass:"line-numbers-wrapper"},[s("span",{staticClass:"line-number"},[t._v("1")]),s("br")])]),s("h2",{attrs:{id:"udf-queries"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#udf-queries"}},[t._v("#")]),t._v(" UDF Queries")]),t._v(" "),s("p",[t._v("The usage of UDF is similar to that of built-in aggregation functions.")]),t._v(" "),s("h3",{attrs:{id:"basic-sql-syntax-support"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#basic-sql-syntax-support"}},[t._v("#")]),t._v(" Basic SQL syntax support")]),t._v(" "),s("ul",[s("li",[t._v("Support "),s("code",[t._v("SLIMIT")]),t._v(" / "),s("code",[t._v("SOFFSET")])]),t._v(" "),s("li",[t._v("Support "),s("code",[t._v("LIMIT")]),t._v(" / "),s("code",[t._v("OFFSET")])]),t._v(" "),s("li",[t._v("Support "),s("code",[t._v("NON ALIGN")])]),t._v(" "),s("li",[t._v("Support queries with time filters")]),t._v(" "),s("li",[t._v("Support queries with value filters")])]),t._v(" "),s("h3",{attrs:{id:"queries-with-in-select-clauses"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#queries-with-in-select-clauses"}},[t._v("#")]),t._v(" Queries with * in SELECT Clauses")]),t._v(" "),s("p",[t._v("Assume that there are 2 time series ("),s("code",[t._v("root.sg.d1.s1")]),t._v(" and "),s("code",[t._v("root.sg.d1.s2")]),t._v(")  in the system.")]),t._v(" "),s("ul",[s("li",[s("strong",[s("code",[t._v("SELECT example(*) from root.sg.d1")])])])]),t._v(" "),s("p",[t._v("Then the result set will include the results of "),s("code",[t._v("example (root.sg.d1.s1)")]),t._v(" and "),s("code",[t._v("example (root.sg.d1.s2)")]),t._v(".")]),t._v(" "),s("ul",[s("li",[s("strong",[s("code",[t._v("SELECT example(s1, *) from root.sg.d1")])])])]),t._v(" "),s("p",[t._v("Then the result set will include the results of "),s("code",[t._v("example(root.sg.d1.s1, root.sg.d1.s1)")]),t._v(" and "),s("code",[t._v("example(root.sg.d1.s1, root.sg.d1.s2)")]),t._v(".")]),t._v(" "),s("ul",[s("li",[s("strong",[s("code",[t._v("SELECT example(*, *) from root.sg.d1")])])])]),t._v(" "),s("p",[t._v("Then the result set will include the results of  "),s("code",[t._v("example(root.sg.d1.s1, root.sg.d1.s1)")]),t._v(", "),s("code",[t._v("example(root.sg.d1.s2, root.sg.d1.s1)")]),t._v(", "),s("code",[t._v("example(root.sg.d1.s1, root.sg.d1.s2)")]),t._v(" and "),s("code",[t._v("example(root.sg.d1.s2, root.sg.d1.s2)")]),t._v(".")]),t._v(" "),s("h3",{attrs:{id:"queries-with-key-value-attributes-in-udf-parameters"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#queries-with-key-value-attributes-in-udf-parameters"}},[t._v("#")]),t._v(" Queries with Key-value Attributes in UDF Parameters")]),t._v(" "),s("p",[t._v("You can pass any number of key-value pair parameters to the UDF when constructing a UDF query. The key and value in the key-value pair need to be enclosed in single or double quotes. Note that key-value pair parameters can only be passed in after all time series have been passed in. Here is a set of examples:")]),t._v(" "),s("div",{staticClass:"language-sql line-numbers-mode"},[s("pre",{pre:!0,attrs:{class:"language-sql"}},[s("code",[s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("SELECT")]),t._v(" example"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),t._v("s1"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(",")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token string"}},[t._v('"key1"')]),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),s("span",{pre:!0,attrs:{class:"token string"}},[t._v('"value1"')]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(",")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token string"}},[t._v('"key2"')]),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),s("span",{pre:!0,attrs:{class:"token string"}},[t._v('"value2"')]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(",")]),t._v(" example"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("*")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(",")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token string"}},[t._v('"key3"')]),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),s("span",{pre:!0,attrs:{class:"token string"}},[t._v('"value3"')]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("FROM")]),t._v(" root"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),t._v("sg"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),t._v("d1"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n"),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("SELECT")]),t._v(" example"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),t._v("s1"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(",")]),t._v(" s2"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(",")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token string"}},[t._v('"key1"')]),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),s("span",{pre:!0,attrs:{class:"token string"}},[t._v('"value1"')]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(",")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token string"}},[t._v('"key2"')]),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),s("span",{pre:!0,attrs:{class:"token string"}},[t._v('"value2"')]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("FROM")]),t._v(" root"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),t._v("sg"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),t._v("d1"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n")])]),t._v(" "),s("div",{staticClass:"line-numbers-wrapper"},[s("span",{staticClass:"line-number"},[t._v("1")]),s("br"),s("span",{staticClass:"line-number"},[t._v("2")]),s("br")])]),s("h3",{attrs:{id:"hybrid-queries"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#hybrid-queries"}},[t._v("#")]),t._v(" Hybrid Queries")]),t._v(" "),s("p",[t._v("Currently IoTDB supports hybrid queries of UDF queries and raw data queries, for example:")]),t._v(" "),s("div",{staticClass:"language-sql line-numbers-mode"},[s("pre",{pre:!0,attrs:{class:"language-sql"}},[s("code",[s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("SELECT")]),t._v(" s1"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(",")]),t._v(" s2"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(",")]),t._v(" example"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),t._v("s1"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(",")]),t._v(" s2"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("FROM")]),t._v(" root"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),t._v("sg"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),t._v("d1"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n"),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("SELECT")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("*")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(",")]),t._v(" example"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("*")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("FROM")]),t._v(" root"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),t._v("sg"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),t._v("d1 NON ALIGN"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n")])]),t._v(" "),s("div",{staticClass:"line-numbers-wrapper"},[s("span",{staticClass:"line-number"},[t._v("1")]),s("br"),s("span",{staticClass:"line-number"},[t._v("2")]),s("br")])]),s("h2",{attrs:{id:"show-all-registered-udfs"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#show-all-registered-udfs"}},[t._v("#")]),t._v(" Show All Registered UDFs")]),t._v(" "),s("div",{staticClass:"language-sql 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:"user-permission-management"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#user-permission-management"}},[t._v("#")]),t._v(" User Permission Management")]),t._v(" "),s("p",[t._v("There are 3 types of user permissions related to UDF:")]),t._v(" "),s("ul",[s("li",[s("code",[t._v("CREATE_FUNCTION")]),t._v(": Only users with this permission are allowed to register UDFs")]),t._v(" "),s("li",[s("code",[t._v("DROP_FUNCTION")]),t._v(": Only users with this permission are allowed to deregister UDFs")]),t._v(" "),s("li",[s("code",[t._v("READ_TIMESERIES")]),t._v(": Only users with this permission are allowed to use UDFs for queries")])]),t._v(" "),s("p",[t._v("For more user permissions related content, please refer to "),s("RouterLink",{attrs:{to:"/UserGuide/Master/Operation Manual/Administration.html"}},[t._v("Account Management Statements")]),t._v(".")],1),t._v(" "),s("h2",{attrs:{id:"configurable-properties"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#configurable-properties"}},[t._v("#")]),t._v(" Configurable Properties")]),t._v(" "),s("p",[t._v("When querying by a UDF, IoTDB may prompt that there is insufficient memory. You can resolve the issue by configuring "),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(" and "),s("code",[t._v("udf_reader_transformer_collector_memory_proportion")]),t._v(" in "),s("code",[t._v("iotdb-engine.properties")]),t._v(" and restarting the server.")]),t._v(" "),s("h2",{attrs:{id:"contribute-udf"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#contribute-udf"}},[t._v("#")]),t._v(" Contribute UDF")]),t._v(" "),s("p",[t._v("This part mainly introduces how external users can contribute their own UDFs to the IoTDB community.")]),t._v(" "),s("h3",{attrs:{id:"prerequisites"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#prerequisites"}},[t._v("#")]),t._v(" Prerequisites")]),t._v(" "),s("ol",[s("li",[s("p",[t._v("UDFs must be universal.")]),t._v(" "),s("p",[t._v('The "universal" mentioned here refers to: UDFs can be widely used in some scenarios. In other words, the UDF function must have reuse value and may be directly used by other users in the community.')]),t._v(" "),s("p",[t._v("If you are not sure whether the UDF you want to contribute is universal, you can send an email to "),s("code",[t._v("dev@iotdb.apache.org")]),t._v(" or create an issue to initiate a discussion.")])]),t._v(" "),s("li",[s("p",[t._v("The UDF you are going to contribute has been well tested and can run normally in the production environment.")])])]),t._v(" "),s("h3",{attrs:{id:"what-you-need-to-prepare"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#what-you-need-to-prepare"}},[t._v("#")]),t._v(" What you need to prepare")]),t._v(" "),s("ol",[s("li",[t._v("UDF source code")]),t._v(" "),s("li",[t._v("Test cases")]),t._v(" "),s("li",[t._v("Instructions")])]),t._v(" "),s("h4",{attrs:{id:"udf-source-code"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#udf-source-code"}},[t._v("#")]),t._v(" UDF Source Code")]),t._v(" "),s("ol",[s("li",[t._v("Create the UDF main class and related classes in "),s("code",[t._v("src/main/java/org/apache/iotdb/db/query/udf/builtin")]),t._v(" or in its subfolders.")]),t._v(" "),s("li",[t._v("Register your UDF in "),s("code",[t._v("src/main/java/org/apache/iotdb/db/query/udf/builtin/BuiltinFunction.java")]),t._v(".")])]),t._v(" "),s("h4",{attrs:{id:"test-cases"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#test-cases"}},[t._v("#")]),t._v(" Test Cases")]),t._v(" "),s("p",[t._v("At a minimum, you need to write integration tests for the UDF.")]),t._v(" "),s("p",[t._v("You can add a test class in "),s("code",[t._v("server/src/test/java/org/apache/iotdb/db/integration")]),t._v(".")]),t._v(" "),s("h4",{attrs:{id:"instructions"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#instructions"}},[t._v("#")]),t._v(" Instructions")]),t._v(" "),s("p",[t._v("The instructions need to include: the name and the function of the UDF, the attribute parameters that must be provided when the UDF is executed, the applicable scenarios, and the usage examples, etc.")]),t._v(" "),s("p",[t._v("The instructions should be added in "),s("code",[t._v("docs/UserGuide/Operation Manual/DML Data Manipulation Language.md")]),t._v(".")]),t._v(" "),s("h3",{attrs:{id:"submit-a-pr"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#submit-a-pr"}},[t._v("#")]),t._v(" Submit a PR")]),t._v(" "),s("p",[t._v("When you have prepared the UDF source code, test cases, and instructions, you are ready to submit a Pull Request (PR) on "),s("a",{attrs:{href:"https://github.com/apache/iotdb",target:"_blank",rel:"noopener noreferrer"}},[t._v("Github"),s("OutboundLink")],1),t._v(". You can refer to our code contribution guide to submit a PR: "),s("a",{attrs:{href:"https://iotdb.apache.org/Development/HowToCommit.html",target:"_blank",rel:"noopener noreferrer"}},[t._v("Pull Request Guide"),s("OutboundLink")],1),t._v(".")]),t._v(" "),s("h2",{attrs:{id:"known-implementation-udf-libraries"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#known-implementation-udf-libraries"}},[t._v("#")]),t._v(" Known Implementation UDF Libraries")]),t._v(" "),s("ul",[s("li",[s("a",{attrs:{href:"https://thulab.github.io/iotdb-quality",target:"_blank",rel:"noopener noreferrer"}},[t._v("IoTDB-Quality"),s("OutboundLink")],1),t._v(", a UDF library about data quality, including data profiling, data quality evalution and data repairing, etc.")])]),t._v(" "),s("h2",{attrs:{id:"q-a"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#q-a"}},[t._v("#")]),t._v(" Q&A")]),t._v(" "),s("p",[t._v("Q1: **How to modify the registered UDF? **")]),t._v(" "),s("p",[t._v("A1: Assume that the name of the UDF is "),s("code",[t._v("example")]),t._v(" and the full class name is "),s("code",[t._v("org.apache.iotdb.udf.ExampleUDTF")]),t._v(", which is introduced by "),s("code",[t._v("example.jar")]),t._v(".")]),t._v(" "),s("ol",[s("li",[t._v("Unload the registered function by executing "),s("code",[t._v("DROP FUNCTION example")]),t._v(".")]),t._v(" "),s("li",[t._v("Delete "),s("code",[t._v("example.jar")]),t._v(" under "),s("code",[t._v("iotdb-server-0.12.0-SNAPSHOT/ext/udf")]),t._v(".")]),t._v(" "),s("li",[t._v("Modify the logic in "),s("code",[t._v("org.apache.iotdb.udf.ExampleUDTF")]),t._v(" and repackage it. The name of the JAR package can still be "),s("code",[t._v("example.jar")]),t._v(".")]),t._v(" "),s("li",[t._v("Upload the new JAR package to "),s("code",[t._v("iotdb-server-0.12.0-SNAPSHOT/ext/udf")]),t._v(".")]),t._v(" "),s("li",[t._v("Load the new UDF by executing "),s("code",[t._v('CREATE FUNCTION example AS "org.apache.iotdb.udf.ExampleUDTF"')]),t._v(".")])])])}),[],!1,null,null,null);a.default=n.exports}}]);