MaxCompute:Java UDTFs

Methods

You can use Java data types or Java writable types in a Java UDTF. For type mappings, see Data types.

The following example shows the complete code structure of a Java UDTF:

// Package Java classes into a JAR file named org.alidata.odps.udtf.examples.
package org.alidata.odps.udtf.examples;
// Base UDTF classes.
import com.aliyun.odps.udf.UDTF;
import com.aliyun.odps.udf.UDTFCollector;
import com.aliyun.odps.udf.annotation.Resolve;
import com.aliyun.odps.udf.UDFException;

// Splits a string by whitespace and emits one row per token, paired with the original bigint value.
@Resolve("string,bigint->string,bigint")
public class MyUDTF extends UDTF {
    @Override
    public void process(Object[] args) throws UDFException {
        String a = (String) args[0];
        Long b = (Long) args[1];
        for (String t : a.split("\\s+")) {
            forward(t, b);
        }
    }
}

Prerequisites

Before you begin, ensure that you have:

• MaxCompute Studio installed

• A MaxCompute project connected in MaxCompute Studio

• A MaxCompute Java module created

Write UDTF code

1. In the Project tab, navigate to src > main > java, right-click java, and choose New > MaxCompute Java.

   

2. In the Create new MaxCompute java class dialog box, click UDTF, enter a name in the Name field, and press Enter. This example uses MyUDTF as the class name. If you have not created a package yet, specify the name in packagename.classname format. MaxCompute Studio generates the package automatically.

   

3. Write the following code in the editor:

   package org.alidata.odps.udtf.examples;
   import com.aliyun.odps.udf.UDTF;
   import com.aliyun.odps.udf.UDTFCollector;
   import com.aliyun.odps.udf.annotation.Resolve;
   import com.aliyun.odps.udf.UDFException;
   
   // Splits the first string argument by whitespace and emits one row per token,
   // pairing each token with the original bigint value.
   @Resolve("string,bigint->string,bigint")
   public class MyUDTF extends UDTF {
       @Override
       public void process(Object[] args) throws UDFException {
           String a = (String) args[0];
           Long b = (Long) args[1];
           for (String t : a.split("\\s+")) {
               forward(t, b);
           }
       }
   }

   

Debug locally

Run the UDTF on your local machine to verify that the code works before uploading it.

For debug instructions, see Perform a local run to debug the UDF.

Register the UDTF

Package the UDTF into a JAR file, upload it to your MaxCompute project, and register it as a function. This example registers the function as user_udtf.

For packaging instructions, see Procedure.

Call the UDTF in SQL

In Project Explorer, right-click your MaxCompute project and select Open in Console to open the MaxCompute client.

The input table my_table has the following structure:

+------------+------------+
| col0       | col1       |
+------------+------------+
| A B        | 1          |
| C D        | 2          |
+------------+------------+

Run the following statement to call the UDTF:

SELECT user_udtf(col0, col1) AS (c0, c1) FROM my_table;

Expected output:

+----+------------+
| c0 | c1         |
+----+------------+
| A  | 1          |
| B  | 1          |
| C  | 2          |
| D  | 2          |
+----+------------+