A = LOAD '/path/to/data.json' USING com.twitter.elephantbird.pig.load.JsonLoader('-nestedLoad')
To extract unique values from a column in a relation you can use DISTINCT or GROUP BY/GENERATE. DISTINCT is the preferred method; it is faster and more efficient.
Example using GROUP BY - GENERATE:
A = load 'myfile' as (t, u, v); B = foreach A generate u; C = group B by u; D = foreach C generate group as uniquekey; dump D; Example using DISTINCT:
A = load 'myfile' as (t, u, v); B = foreach A generate u; C = distinct B; dump C;
