我如何在Apache PIG中正确执行内部连接？ [英] How can I do this inner join properly in Apache PIG?

问题描述

我有两个档案，一个叫做a-records

I have two files, one called a-records

123^record1
222^record2
333^record3

和另一个名为b-records的文件

and the other file called b-records

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

你可以在文件A中看到我有令牌123一次。在文件B中它有两次。有没有办法使用Apache PIG我可以加入数据，这样我只能从A文件中获得一个连接记录？

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?

这里是我当前的脚本，输出如下

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;

其中：

which yields:

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

当我真正想要的是（注意令牌123只存在于加入）

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)

有什么想法吗？非常感谢

any ideas? thanks so much

推荐答案

我会这样做：

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;

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