我不能在某些领域使用我的自定义项，但我可以在其他领域使用它。如果我用我的第一个领域， ipAddress ，自定义项按预期工作。但是，如果我把它改成 date 我发现了1066的错误。这是我的剧本。

Pig脚本的工作和调用自定义项。

REGISTER myudfs.jar;
DEFINE HOUR myudfs.HOUR;

A = load 'access_log_Jul95' using PigStorage(' ') as (ip:chararray, dash1:chararray, dash2:chararray, date:chararray, date1:chararray, getRequset:chararray, location:chararray, http:chararray, code:int, port:int);
B = FOREACH A GENERATE HOUR(ip);
dump B;

pig脚本不起作用，并调用udf

REGISTER myudfs.jar;
DEFINE HOUR myudfs.HOUR;

A = load 'access_log_Jul95' using PigStorage(' ') as (ip:chararray, dash1:chararray, dash2:chararray, date:chararray, date1:chararray, getRequset:chararray, location:chararray, http:chararray, code:int, port:int);
B = FOREACH A GENERATE HOUR(date);
dump B;

pig脚本，但不调用udf

REGISTER myudfs.jar;
DEFINE HOUR myudfs.HOUR;

A = load 'access_log_Jul95' using PigStorage(' ') as (ip:chararray, dash1:chararray, dash2:chararray, date:chararray, date1:chararray, getRequset:chararray, location:chararray, http:chararray, code:int, port:int);
B = FOREACH A GENERATE date;
dump B;

样本数据

199.72.81.55 - - [01/Jul/1995:00:00:01 -0400] "GET /history/apollo/ HTTP/1.0" 200 6245

java自定义项

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 HOUR extends EvalFunc<String>
 {
        @SuppressWarnings("deprecation")
        public String exec(Tuple input) throws IOException {
            if (input == null || input.size() == 0)
                return " ";
         try{
             String str = (String)input.get(0);
                return str.substring(0, 1);
            }catch(Exception e){
                throw WrappedIOException.wrap("Caught exception processing input row ", e);
            }
        }
 }

错误

ERROR org.apache.pig.tools.grunt.Grunt - ERROR 1066: Unable to open iterator for alias B

如果还有什么事，请告诉我。我在本地运行这个错误，并在map reduce上运行。