What do you understand by an inner bag and outer bag in Pig

Question

Can you help me with this differentiation?

Answer 1

Outer bag or relation is nothing but a bag of tuples. Here relations are similar as relations in relational databases. For example:

{(Linkin Park, California), (Metallica, Los Angeles), (Mega Death, Los Angeles)}

An inner bag contains a bag inside a tuple. For Example:

(Los Angeles, {(Metallica, Los Angeles), (Mega Death, Los Angeles)})

(California, {(Linkin Park, California)})