Pig SPLIT 运算符



  • Union 运算符

    Pig Latin的SPLIT运算符用于关系分成两个或更多的关系。
    句法
    下面给出的是SPLIT运算符的语法。
    
    grunt> SPLIT Relation1_name INTO Relation2_name IF (condition1), Relation2_name (condition2)
    
    
    假设我们在HDFS目录/pig_data/中有一个名为student_details.txt的文件,如下所示。
    
    001,Rajiv,Reddy,21,9848022337,Hyderabad
    002,siddarth,Battacharya,22,9848022338,Kolkata
    003,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
    
    
    并且我们已经将该文件加载到Pig中,关系名称为student_details,如下所示。
    
    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); 
    
    
    现在让我们将该关系分为两个,一个列出年龄小于23岁的雇员,另一个列出年龄在22至25岁之间的雇员。
    
    SPLIT student_details into student_details1 if age<23, student_details2 if (22 < age and age > 25);
    
    
    验证
    如下所示,使用DUMP运算符验证关系Student_details1和student_details2。
    
    grunt> Dump student_details1;  
    
    grunt> Dump student_details2; 
    
    
    输出
    它将产生以下输出,分别显示关系student_details1和student_details2的内容。
    
    grunt> Dump student_details1; 
    (1,Rajiv,Reddy,21,9848022337,Hyderabad) 
    (2,siddarth,Battacharya,22,9848022338,Kolkata)
    (3,Rajesh,Khanna,22,9848022339,Delhi) 
    (4,Preethi,Agarwal,21,9848022330,Pune)
      
    grunt> Dump student_details2; 
    (5,Trupthi,Mohanthy,23,9848022336,Bhuwaneshwar) 
    (6,Archana,Mishra,23,9848022335,Chennai) 
    (7,Komal,Nayak,24,9848022334,trivendram) 
    (8,Bharathi,Nambiayar,24,9848022333,Chennai)