Apache Pig Distinct operator

The DISTINCT operator is used to remove redundant (duplicate) fuses from relationships.

Grammar

The syntax of the DISTINCT operator is given below.

grunt> Relation_name2 = DISTINCT Relatin_name1;

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,9848022337,Hyderabad
002,siddarth,Battacharya,9848022338,Kolkata 
002,siddarth,Battacharya,9848022338,Kolkata 
003,Rajesh,Khanna,9848022339,Delhi 
003,Rajesh,Khanna,9848022339,Delhi 
004,Preethi,Agarwal,9848022330,Pune 
005,Trupthi,Mohanthy,9848022336,Bhuwaneshwar
006,Archana,Mishra,9848022335,Chennai 
006,Archana,Mishra,9848022335,Chennai

The relationship student_details load 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, phone:chararray, city:chararray);

Now, let's use the DISTINCT operator to remove redundant (duplicate) marshals from the student_details relationship and have another relationship called distinct_data as shown below.

grunt> distinct_data = DISTINCT student_details;

Verify

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

grunt> Dump distinct_data;

Output

It produces the following output, showing the relationship distinct_data as follows.

(1,Rajiv,Reddy,9848022337,Hyderabad)
(2,siddarth,Battacharya,9848022338,Kolkata) 
(3,Rajesh,Khanna,9848022339,Delhi) 
(4,Preethi,Agarwal,9848022330,Pune) 
(5,Trupthi,Mohanthy,9848022336,Bhuwaneshwar)
(6,Archana,Mishra,9848022335,Chennai)