Вложенный анализ в XPath с использованием Pig

Question

Я пытаюсь разобрать XML-файл с вложенными тегами с помощью свиньи. У меня ниже образца для xml.

<Document> 
    <medicationsInfo> 
    <code>10160-0</code> 
    <entryInfo> 
     <statusCode>completed</statusCode> 
     <startTime>20110729</startTime> 
     <endTime>20110822</endTime> 
     <strengthValue>24</strengthValue> 
     <strengthUnits>h</strengthUnits> 
    </entryInfo> 
    <entryInfo> 
     <statusCode>completed</statusCode> 
     <startTime>20120130</startTime> 
     <endTime>20120326</endTime> 
     <strengthValue>12</strengthValue> 
     <strengthUnits>h</strengthUnits> 
    </entryInfo> 
    <entryInfo> 
     <statusCode>completed</statusCode> 
     <startTime>20100412</startTime> 
     <endTime>20110822</endTime> 
     <strengthValue>8</strengthValue> 
     <strengthUnits>d</strengthUnits> 
    </entryInfo> 
    </medicationsInfo> 
    <ProductInfo> 
    <code>10160-0</code> 
    <entryInfo> 
     <statusCode>completed</statusCode> 
     <startTime>20110729</startTime> 
     <endTime>20110822</endTime> 
     <strengthValue>24</strengthValue> 
     <strengthUnits>h</strengthUnits> 
    </entryInfo> 
    <entryInfo> 
     <statusCode>completed</statusCode> 
     <startTime>20120130</startTime> 
     <endTime>20120326</endTime> 
     <strengthValue>12</strengthValue> 
     <strengthUnits>h</strengthUnits> 
    </entryInfo> 
    <entryInfo> 
     <statusCode>completed</statusCode> 
     <startTime>20100412</startTime> 
     <endTime>20110822</endTime> 
     <strengthValue>8</strengthValue> 
     <strengthUnits>d</strengthUnits> 
    </entryInfo> 
    </ProductInfo> 
    </Document> 

Я пишу ниже, чтобы получить результаты ввода данных medicationsinfo, но я получаю ошибку.

Код:

Register /home/cloudera/piggybank-0.16.0.jar; 
DEFINE XPathAll org.apache.pig.piggybank.evaluation.xml.XPathAll(); 
DEFINE XPath org.apache.pig.piggybank.evaluation.xml.XPath(); 
A = LOAD '/home/cloudera/Parsed_CCD.xml' using org.apache.pig.piggybank.storage.XMLLoader('medicationsInfo/entryInfo') as (x:chararray); 
B = FOREACH A GENERATE XPathAll(x, 'statusCode',false,true), XPathAll(x, 'medicationsInfo/code/code',false,true).$0, XPathAll(x,'strengthValue',false,true).$1; 
DUMP B; 

Ошибка:

[main] INFO org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MapReduceLauncher - Failed! [main] ERROR org.apache.pig.tools.grunt.Grunt - ERROR 1066: Unable to open iterator for alias B

Ожидаемый результат:

completed 20110729 20110822 24 h 
completed 20120130 20120326 12 h 
completed 20100412 20110822 8 d 

Answer 1

Ниже код будет генерировать ожидаемый результат:

Register /home/cloudera/piggybank-0.16.0.jar; 

DEFINE XPathAll org.apache.pig.piggybank.evaluation.xml.XPathAll(); 

--DEFINE XPath org.apache.pig.piggybank.evaluation.xml.XPath(); 

A = LOAD 'home/cloudera/Parsed_CCD.xml' 
using org.apache.pig.piggybank.storage.XMLLoader('medicationsInfo') as (x:chararray); 

B = FOREACH A GENERATE 
XPathAll(x, 'medicationsInfo/entryInfo/statusCode').$0, 
XPathAll(x, 'medicationsInfo/entryInfo/startTime').$0, 
XPathAll(x, 'medicationsInfo/entryInfo/endTime').$0, 
XPathAll(x, 'medicationsInfo/entryInfo/strengthValue').$0, 
XPathAll(x, 'medicationsInfo/entryInfo/strengthUnits').$0; 

C = FOREACH A GENERATE 
XPathAll(x, 'medicationsInfo/entryInfo/statusCode').$1, 
XPathAll(x, 'medicationsInfo/entryInfo/startTime').$1, 
XPathAll(x, 'medicationsInfo/entryInfo/endTime').$1, 
XPathAll(x, 'medicationsInfo/entryInfo/strengthValue').$1, 
XPathAll(x, 'medicationsInfo/entryInfo/strengthUnits').$1; 

D = FOREACH A GENERATE 
XPathAll(x, 'medicationsInfo/entryInfo/statusCode').$2, 
XPathAll(x, 'medicationsInfo/entryInfo/startTime').$2, 
XPathAll(x, 'medicationsInfo/entryInfo/endTime').$2, 
XPathAll(x, 'medicationsInfo/entryInfo/strengthValue').$2, 
XPathAll(x, 'medicationsInfo/entryInfo/strengthUnits').$2; 


BCD = UNION B,C,D; 

DUMP BCD;