Question

这是我工作的样本数据：

Peter   Wilkerson   27  M
James   Owen    26  M
Matt    Wo  30  M
Kenny   Chen    28  M

我创建了一个简单的UDF来过滤这样的年龄：

public class IsApplicable extends FilterFunc {

    @Override
    public Boolean exec(Tuple tuple) throws IOException {
        if(tuple == null || tuple.size() > 0){
            return false;
        }
        try {
            Object object = tuple.get(0);
            if(object == null){
                return false;
            }
            int age = (Integer)object;
            return age > 28;
        } catch (Exception e) {
            throw new IOException(e);
        }
    }

}

这是我用于使用此UDF的脚本：

records = LOAD '~/Documents/data.txt' AS (firstname:chararray,lastname:chararray,age:int,gender:chararray);
filtered_records = FILTER records BY com.udf.IsApplicable(age);
dump filtered_records;

转储不显示任何记录。请告诉我错过的地方。

Answer 1

{p> tuple.size() > 0条件always true中的if stmt条件，因此它永远不会转到try block(ie filtering logic)，这就是您获得空结果的原因。你能改变像这样的if条件吗？

     System.out.println("TupleSize="+tuple.size());
     if(tuple == null || tuple.size() < 0){
            return false;
        }

控制台中的调试输出示例：

2015-02-13 07:40:46,994 [Thread-2] INFO  org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigMapOnly$Map - Aliases being processed per job phase (AliasName[line,offset]): M: records[3,10],records[-1,-1],filtered_records[4,19] C:  R: 
TupleSize=1
TupleSize=1
TupleSize=1

Answer 2

这会为所有行返回false：

if (tuple == null || tuple.size() > 0) {
    return false;
}

这是取userName而非age：

Object object = tuple.get(0);

Pig：UDF没有返回预期的结果集

2 个答案: