The DISTINCT operator is used to remove redundant (duplicate) tuples from a relation.

Syntax

Given below is the syntax of theDISTINCToperator.

grunt
>
 Relation_name2 = DISTINCT Relatin_name1;

Example

Assume that we have a file namedstudent_details.txtin the HDFS directory/pig_data/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

And we have loaded this file into Pig with the relation namestudent_detailsas 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
);

Let us now remove the redundant (duplicate) tuples from the relation namedstudent_detailsusing theDISTINCToperator, and store it as another relation nameddistinct_dataas shown below.

grunt
>
 distinct_data = DISTINCT student_details;

Verification

Verify the relationdistinct_datausing theDUMPoperator as shown below.

grunt
>
Dump
 distinct_data
;

Output

It will produce the following output, displaying the contents of the relationdistinct_dataas 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)