MapReduce Pig Bug

问题，在运行pig代码时候出现以下错误，强制类型转换的错误，但是在pig中并没有出现强制转换的语句（引用了UDF）。

AttemptID:attempt_1499336294438_15015_m_000001_0 Info:Error: java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.String    at org.apache.pig.backend.hadoop.HDataType.getWritableComparableTypes(HDataType.java:106)    at org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigGenericMapReduce$Map.collect(PigGenericMapReduce.java:111)    at org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigGenericMapBase.runPipeline(PigGenericMapBase.java:284)    at org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigGenericMapBase.map(PigGenericMapBase.java:277)    at org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigGenericMapBase.map(PigGenericMapBase.java:64)    at org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:145)    at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:787)    at org.apache.hadoop.mapred.MapTask.run(MapTask.java:341)    at org.apache.hadoop.mapred.YarnChild$2.run(YarnChild.java:163)    at java.security.AccessController.doPrivileged(Native Method)    at javax.security.auth.Subject.doAs(Subject.java:415)    at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1671)    at org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:158)

解决方案和问题原因

data_grp = FOREACH Data GENERATE FLATTEN(grp(type,lon,lat)) AS grpnumber:double;

这里调用UDF并且另命名为其他列，注意这里的数据类型要和UDF中返回的数据类型一致，如果不一致将会出现上面的那个错误。

package cn.sibat.taxi.sum;import cn.sibat.taxi.sum.util.LocationUtil;import org.apache.pig.EvalFunc;import org.apache.pig.data.Tuple;import org.apache.pig.data.TupleFactory;import java.io.IOException;import java.util.ArrayList;import java.util.List;/** * Created by User on 2017/9/20. */public class Divide extends EvalFunc<Tuple> {    //粤B093YU,2016-12-31T23:02:20.000Z,113.95858,22.543633,1    static int groupnumber = 0;    static List<Tuple> store= new ArrayList<Tuple>();    static double sum =0;    static double final_sum = 0;    @Override    public Tuple exec(Tuple tuple) throws IOException {        TupleFactory tupleFactory = TupleFactory.getInstance();        Tuple out = tupleFactory.newTuple();        if (tuple.get(0) != null) {            int type = Integer.parseInt(tuple.get(0).toString());            if (store.size() == 0 || type == 1) {                store.add(tuple);               // out.append("-1");               // return out;            } else if (type == 0) {                groupnumber++;                for (int i = 0; i < store.size() - 1; i++) {                    double distance = LocationUtil.distance(Double.parseDouble(store.get(i).get(1).toString()),                            Double.parseDouble(store.get(i).get(2).toString()),                            Double.parseDouble(store.get(i + 1).get(1).toString()),                            Double.parseDouble(store.get(i + 1).get(2).toString()));                    if (distance == 0 || distance > 1500) {//上下两点的距离等于0或大于1500米，过滤                        continue;                    }                    //System.out.println("d:" + distance);                    sum += distance;                }                final_sum=final_sum+sum;                out.append(final_sum);// final_sum 是double类型所以在pig中也是double类型                store.clear();                //final_sum=final_sum+sum;                sum = 0;            }        }        return out;    }    }