不在，猪匹配

Question

我在猪身上有两个关系：

A，B

DUMP A;

  

Sandeep Rohan Mohan

DUMP B;

  

MOHAN

我需要输出A - B; 关系C应该给我

  

和Sandeep，罗汉

因为他们没有出现在B

Answer 1

试试这个：

A1 = LOAD 'Sandeep Rohan Mohan' USING PigStorage() AS (line:chararray);
B1 = LOAD 'MOHAN' USING PigStorage() AS (line:chararray);

A = FOREACH A1 GENERATE UPPER(line) AS line;
B = FOREACH B1 GENERATE UPPER(line) AS line;

C = COGROUP A BY line, B BY line;

D = FILTER C BY IsEmpty(B);

E = FOREACH D GENERATE group AS name;

DUMP E;

  

（ROHAN）（SANDEEP）

也请参考sets operations in apache pig

Answer 2

使用左外连接实现它，只考虑那些在$ 1中有空值的元组