[Solved-1 Solution] How to add a column to an already existing table in apache pig ?
Problem :
How to add a column to an already existing table in apache pig ?
Solution 1:
We can use random for this purpose
Example
A = ...
B = foreach A generate (int)(RANDOM()*100.0) as rnd, [other fields...]
Random Function
- The RANDOM() function is used to get a pseudo random number (type double) greater than or equal to 0.0 and less than 1.0.
grunt> RANDOM()
Example
- Assume that there is a file named math.txt in the HDFS directory
/pig_data/. - This file contains integer and floating point values as shown below.
math.txt
5
16
9
2.5
5.9
3.1
- we have loaded this file into Pig with a relation named math_data as shown below.
grunt> math_data = LOAD 'hdfs://localhost:9000/pig_data/math.txt' USING PigStorage(',')
as (data:float);
- Let us now generate random values of the contents of the math.txt file using RANDOM() function as shown below.
grunt> random_data = foreach math_data generate (data), RANDOM();
- The above statement stores the result in the relation named random_data. Verify the contents of the relation using the Dump operator as shown below.
grunt> Dump random_data;
(5.0,0.6842057767279982)
(16.0,0.9725172591786139)
(9.0,0.4159326414649489)
(2.5,0.30962777780713147)
(5.9,0.705213727551145)
(3.1,0.24247708413861724)