Apache Pig Order By operator

The ORDER BY operator is used to display the contents of a relationship in a sort order based on one or more fields.

Grammar

The syntax of the ORDER BY operator is given below.

grunt> Relation_name2 = ORDER Relatin_name1 BY (ASC|DESC);

Cases

Suppose you have a file called pig_data in the HDFS directory /student_details.txt, as shown below.

student_details.txt

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

The relationship student_details loads this file into pig, as shown below.

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);

Now let's arrange the relationships in descending order based on the student's age and store them in another relationship called order_by_data using the ORDER BY operator, as shown below.

grunt> order_by_data = ORDER student_details BY age DESC;

Verify

Use the DUMP operator to validate the relationship order_by_data, as shown below.

grunt> Dump order_by_data; 

Output

It produces the following output, which shows the order_by_data relationship.

(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)