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What is MIN Function in Apache Pig ?
- The MIN() function used in Apache Pig is used to get the minimum value for a certain column in a single-column bag
- The MIN() function will ignore the NULL values while calculating the minimum values
- The MIN() function will requires a preceding GROUP ALL statement for the global minimums and a GROUP BY statement for the group minimums.
- The MIN() function return the minimum value which is given in a set of values and also will return the smallest value of the column which is given in the table.
- The MIN() function will return the smallest numeric value in a range of values and it will ignores the empty cells.
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Syntax
grunt> MIN(expression)
Example
wikitechy_employee_details.txt
001,Guru,Reddy,21,9848022337,Hyderabad,89
002,sabrina,Battacharya,22,9848022338,Kolkata,78
003,Ramesh,Khanna,22,9848022339,Delhi,90
004,Preethi,Agarwal,21,9848022330,Pune,93
005,Sruthi,Mohanthy,23,9848022336,Bhuwaneshwar,75
006,Vanitha,Mishra,23,9848022335,Chennai,87
007,Kamal,Nayak,24,9848022334,trivendram,83
008,Sharath,Nambiayar,24,9848022333,Chennai,72
- We have loaded this file into Pig with the relation name wikitechy_employee_details which is given below:
grunt> wikitechy_employee_details = LOAD 'hdfs://localhost:9000/pig_data/wikitechy_employee_details.txt' USING PigStorage(',')
as (id:int, firstname:chararray, lastname:chararray, age:int, phone:chararray, city:chararray, gpa:int);
Calculating the Minimum GPA
- We can group the relation wikitechy_employee_details by using the Group All operator, and we can store the result in the relation called employee_group_all which is given below
grunt> employee_group_all = Group wikitechy_employee_details All;
- It will produce a relation for calculating the minimum gpa as shown below.
<b>grunt> Dump employee_group_all;</b>
(all,{(8,Sharath,Nambiayar,24,9848022333,Chennai,72),
(7,Kamal,Nayak,24,9848022 334,trivendram,83),
(6,Vanitha,Mishra,23,9848022335,Chennai,87),
(5,Sruthi,Mohan thy,23,9848022336,Bhuwaneshwar,75),
(4,Preethi,Agarwal,21,9848022330,Pune,93),
(3 ,Ramesh,Khanna,22,9848022339,Delhi,90),
(2,sabrina,Battacharya,22,9848022338,Ko lkata,78),
(1,Guru,Reddy,21,9848022337,Hyderabad,89)})
- Now, we need to calculate the global minimum of GPA, of all the employees by using the MIN() function which is given below:
grunt> employee_gpa_min = foreach employee_group_all Generate
(employee_details.firstname, wikitechy_employee_details.gpa), MIN(wikitechy_employee_details.gpa);
Verification
grunt> Dump employee_gpa_min;
Output
(({(Sharath),(Kamal),(Vanitha),(Sruthi),(Preethi),(Ramesh),(sabrina),(Guru) } ,
{ (72) , (83) , (87) , (75) , (93) , (90) , (78) , (89) }) ,72)