In online games, people prefer to log on and off whenever they want. Usually, their game achievements are seamlessly saved, on the server. That is not that difficult to achieve, but I am wondering how can be done in an efficient way that makes sense and will scale.
Does it make sense to save the player's coordinates and state with every time they send it? My node.js server can do that easily without blocking a response, and I want to employ a Mongo database, but maybe it's more appropriate to do that once a second and in a server-wide event, collecting all at once?