P1 a3 fitness document db

A fitness app stores a log of every workout its users do. Different kinds of workout record different things: a run has a distance and a pace for each kilometre, a swim has a number of laps and a stroke, and a weights session has a list of exercises, each with its own list of sets. The app has two million users, and new kinds of workout are added every few months. The developers usually load one whole workout at a time to show it on screen.

Evaluate the use of a document database, rather than a relational database, for the workout logs. [4]