How can I do this inner join properly in Apache PIG?

问题

I have two files, one called a-records

123^record1
222^record2
333^record3

and the other file called b-records

123^jim
123^jim
222^mike
333^joe

you can see in file A that I have the token 123 one time. In file B it's in there twice. Is there a way using Apache PIG I can join the data such that I only get ONE joined record from the A file?

here is my current script which outputs the following below

arecords = LOAD '$a'  USING PigStorage('^')  as (token:chararray, type:chararray);

brecords =  LOAD '$b'  USING PigStorage('^')  as (token:chararray, name:chararray);


x = JOIN arecords BY token, brecords BY token;

dump x;

which yields:

(123,record1,123,jim)
(123,record1,123,jim)
(222,record2,222,mike)
(333,record3,333,joe)

when what I REALLY want is(notice token 123 is only in there once after the join)

(123,record1,123,jim)
(222,record2,222,mike)
(333,record3,333,joe)

any ideas? thanks so much

回答1:

I would do something like this :

arecords = LOAD '$a'  USING PigStorage('^')  as (token:chararray, type:chararray);

brecords =  LOAD '$b'  USING PigStorage('^')  as (token:chararray, name:chararray);

bdistinct = DISTINCT brecords;

x = JOIN arecords BY token, bdistinct BY token;

dump x;

来源：https://stackoverflow.com/questions/7790079/how-can-i-do-this-inner-join-properly-in-apache-pig