hadoop - 如何在具有多个字段的 pig 中加入两个关系

Question

我有两个 CSV 文件:

1- Fertiltiy.csv :

2- Life Expectency.csv :

我想在pig中加入他们，这样结果会是这样的:

我是 pig 的新手，我无法得到正确答案，但这是我的代码:

fertility = LOAD 'fertility' USING org.apache.hcatalog.pig.HCatLoader();

lifeExpectency = LOAD 'lifeExpectency' USING   org.apache.hcatalog.pig.HCatLoader();

A = JOIN fertility by country, lifeExpectency by country; 

B = JOIN fertility by year, lifeExpectency by year; 

C = UNION A,B;

DUMP C; 

这是我的代码的结果:

Answer 1

您可以按国家和年份进行连接，并选择最终输出所需的必要列。

fertility = LOAD 'fertility' USING org.apache.hcatalog.pig.HCatLoader();
lifeExpectency = LOAD 'lifeExpectency' USING   org.apache.hcatalog.pig.HCatLoader();

A = JOIN fertility by (country,year), lifeExpectency by (country,year); 
B = FOREACH A GENERATE  fertility::country,fertility::year,fertility::fertility,lifeExpectency::lifeExpectency;  
DUMP B;