I still don't believe there's a million variables. Can you just list a few of the variables (not all of them) so we can get an idea of what data you're holding. Is it the environment around the robot? - in which case it should just be the time, x pos and y pos, the type of sensor and the value read. If it's internal sensors on the robot then it's just time, sensor id, reading. If it's camera or ultrasonic data then shouldn't you be analysing the data before storing any info.
What environment does the robot explore? what type of sensors are you using? What will you do with the data? Is it a real robot (photo please) or just a pretend one?
Mike