Apache Pig Order By运算符

由 jarodhu 创建，youj 最后一次修改 2016-12-28 ORDER BY 运算符用于以基于一个或多个字段的排序顺序显示关系的内容。语法下面给出了 ORDER BY 运算符的语法。grunt> Relation_name2 = ORDER Relatin_name1 BY (ASC|DESC);例假设在HDFS目录 /pig_data/ 中有一个名为 student_details.txt 的文件，如下所示。 student_details.txt 001,Rajiv,Reddy,21,9848022337,Hyderabad002,siddarth,Battacharya,22,9848022338,Kolkata003,Rajesh,Khanna,22,9848022339,Delhi 004,Preethi,Agarwal,21,9848022330,Pune 005,Trupthi,Mohanthy,23,9848022336,Bhuwaneshwar 006,Archana,Mishra,23,9848022335,Chennai 007,Komal,Nayak,24,9848022334,trivendram 008,Bharathi,Nambiayar,24,9848022333,Chennai通过关系 student_details 将此文件加载到的Pig中，如下所示。grunt> student_details = LOAD 'hdfs://localhost:9000/pig_data/student_details.txt' USING PigStorage(',') as (id:int, firstname:chararray, lastname:chararray,age:int, phone:chararray, city:chararray);现在让我们根据学生的年龄以降序排列关系，并使用 ORDER BY 运算符将它存储到另一个名为 order_by_data 的关系中，如下所示。grunt> order_by_data = ORDER student_details BY age DESC;验证使用 DUMP 运算符验证关系 order_by_data ，如下所示。grunt> Dump order_by_data; 输出它将产生以下输出，显示关系 order_by_data 的内容。(8,Bharathi,Nambiayar,24,9848022333,Chennai)(7,Komal,Nayak,24,9848022334,trivendram)(6,Archana,Mishra,23,9848022335,Chennai) (5,Trupthi,Mohanthy,23,9848022336,Bhuwaneshwar)(3,Rajesh,Khanna,22,9848022339,Delhi) (2,siddarth,Battacharya,22,9848022338,Kolkata)(4,Preethi,Agarwal,21,9848022330,Pune) (1,Rajiv,Reddy,21,9848022337,Hyderabad)