Apache pig script, Error 1070: Java UDF could not

问题:

I am trying to write a Java UDF with the end goal of extending/overriding the load method of PigStorage to support entries that take multiple lines.

My pig script is as follows:

REGISTER udf.jar;
register 'userdef.py' using jython as parser;
A = LOAD 'test_data' USING PigStorage() AS row:chararray;
C = FOREACH A GENERATE myTOKENIZE.test();
DUMP D;

udf.jar looks like:

udf/myTOKENIZE.class

myTOKENIZE.java imports org.apache.pig.* ande extends EvalFunc. the test method just returns a Hello world String.

The problem that I am having is that when I try to call the method test() of class myTOKENIZE I get Error 1070: ERROR 1070: Could not resolve myTOKENIZE.test using imports: [, java.lang., org.apache.pig.builtin., org.apache.pig.impl.builtin.] Thoughts?

回答1:

As your UDF extends EvalFunc there should me a method called exec() in the class myTOKENIZE.

Your pig code would then look as follows:

C = FOREACH A GENERATE udf.myTOKENIZE(*);

Please read http://pig.apache.org/docs/r0.7.0/udf.html#How+to+Write+a+Simple+Eval+Function

Hope that helps.

回答2:

So is myTOKENIZE in the package udf? In that case you'd need

C = FOREACH A GENERATE udf.myTOKENIZE.test();

回答3:

After waaaaay too much time (and coffee) and a bunch a trial and error, I figured out my issue.

Important note: For some jar myudfs.jar, the classes contained within must have package defined as myudfs.

The corrected code is as follows:

REGISTER myudfs.jar;
register 'userdef.py' using jython as parser;
A = LOAD 'test_data' USING PigStorage() AS row:chararray;
C = FOREACH A GENERATE myudfs.myTOKENIZE('');
DUMP C;

myTOKENIZE.java:

package myudfs;
import java.io.IOException;
import org.apache.pig.EvalFunc;
import org.apache.pig.data.Tuple;
import org.apache.pig.impl.util.WrappedIOException;
public class myTOKENIZE extends EvalFunc (String)
{
    public String exec(Tuple input) throws IOException {
        if (input == null || input.size() == 0)
            return null;
        try{
            String str = (String)input.get(0);
            return str.toUpperCase();
        }catch(Exception e){
            throw WrappedIOException.wrap("Caught exception processing input row ", e);
        }
    }
}

the structure of myudfs.jar:

myudfs/myTOKENIZE.class

Hopefully this proves useful to someone else with similar issues!

回答4:

This is very late but I think the solution is that while using the udf in your pig you have to give fully qualified path of the class with your package name. package com.evalfunc.udf; and Power is my class name as public class Power extends EvalFunc<Integer> {....}

Then while using it in pig first register the jar file in pig and then use the udf with full package name like:

record = LOAD '/user/fsbappdev/maitytest/pig/pigudf/power_data' USING PigStorage(',');

pow_result = foreach record generate com.evalfunc.udf.Power(base,exponent);