Going into the PMP exam, it is always helpful to know that the exam is designed by experts who want to know that you thoroughly understand the methods, processes and principles of project management and how you would apply them in a given situation. Most of the exam questions revolve around a given real life scenario and they are based on the PMBOK Guide. That is why the PMP exam is a test of real life project management practices, tools, techniques and principles described in the PMBOK Guide.
It does not mean however, that you are required to memorize the content of the whole PMBOK Guide.
Instead, in order to succeed on the exam, you will need to have a lot of hands-on experience in project management and be able to relate it to the theory in the PMBOK Guide. That's why a minimum of 4,500 hours of experience (7,500 if you don't have a bachelor's degree) is a prerequisite to take the exam. Your real life experience of managing projects in your industry will make everything much easier. Many situations in the questions will be familiar to you because you have lived through them.
So here is my recommendation: Study the PMBOK Guide 2-3 times. Note that I say "study" and not simply "read". Begin applying the principles described on your day to day projects and also relate them back to your previous projects. That way you will see how these principles work. Doing it this way will make you a better project manager and help you pass the exam, as opposed to just mindless memorization