on 2 October 2014
Right now, there's not so much available about Pig Latin.
This book is decent, but I like chapter 10 about Pig in the book Hadoop in Action more, best I found until now.
What is missing in this book and what you find in the mentioned chapter of the other book is clear and simple examples of what output a query produces. That really helps understanding what JOIN, COGROUP, GROUP etc really do.