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UDF description

You can write a user-defined function (UDF), package it into a JAR file, and define it as a function in Data Lake Compute for use in query analysis. Currently, UDFs in Data Lake Compute are in the Hive format and inherit org.apache.hadoop.hive.ql.exec.UDF to implement the evaluate method.
Example: A simple array UDF

public class MyDiff extends UDF {   
   public ArrayList<Integer> evaluate(ArrayList<Integer> input) {
       ArrayList<Integer> result = new ArrayList<Integer>();     
       result.add(0, 0);        
       for (int i = 1; i < input.size(); i++) {              
       result.add(i, input.get(i) - input.get(i - 1));        
       }      
       return result;    
   }
}

Sample POM file

<dependencies>          
   <dependency>        
       <groupId>org.slf4j</groupId>        
        <artifactId>slf4j-log4j12</artifactId>       
        <version>1.7.16</version>        
        <scope>test</scope>    
       </dependency>    
       <dependency>        
           <groupId>org.apache.hive</groupId>        
           <artifactId>hive-exec</artifactId>        
           <version>1.2.1</version>    
       </dependency>
</dependencies>

Creating a function

If you are familiar with the SQL syntax, you can create a function by running the CREATE FUNCTION statement on the Data Explore page. You can also create a function visually in the following steps:

Note：

The data management page of Data Lake Compute is currently in beta test. To try it out, submit a ticket for application.

1. Log in to the Data Lake Compute console and select the service region.
2. Select Data management on the left sidebar and select the target database.
3. Click Function to enter the function management page.
4. Click Create function.
   
   You can also upload a local UDF program package or select a COS path (which requires COS permissions). The following example shows how to create a function by selecting a COS path.
   The function class name includes the package information and the function execution class name.

Using a function

1. Log in to the Data Lake Compute console and select the service region.
2. Select Data Explore on the left sidebar and select a compute engine to use a SQL function.