NOT IN , MATCHES 猪

Posted 2023-04-18

【中文标题】NOT IN , MATCHES 猪

【英文标题】：NOT IN , MATCHES in pig

【发布时间】：2017-02-09 08:18:55

【问题描述】：

我在猪中有两个关系：

A,B

DUMP A;

桑迪普·罗汉·莫汉

DUMP B;

莫汉

我需要得到 A - B 的输出； 关系C应该给我

桑迪普，罗汉

因为它们不存在于 B

【参考方案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;

（罗汉）（桑迪普）

也可以参考sets operations in apache pig

【参考方案2】：

通过左外连接实现它，只考虑那些在 $1 中有空值的元组