Apache Pig - Limit Operator
The LIMIT operator is used to get a limited number of tuples from a relation.
Given below is the syntax of the LIMIT operator.
grunt> Result = LIMIT Relation_name required number of tuples;
Assume that we have a file named student_details.txt in the HDFS directory /pig_data/ as shown below.
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
And we have loaded this file into Pig with the relation name student_details 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 sort the relation in descending order based on the age of the student and store it into another relation named limit_data using the ORDER BY operator as shown below.
grunt> limit_data = LIMIT student_details 4;
Verify the relation limit_data using the DUMP operator as shown below.
grunt> Dump limit_data;
It will produce the following output, displaying the contents of the relation limit_data as follows.
(1,Rajiv,Reddy,21,9848022337,Hyderabad) (2,siddarth,Battacharya,22,9848022338,Kolkata) (3,Rajesh,Khanna,22,9848022339,Delhi) (4,Preethi,Agarwal,21,9848022330,Pune)