Persitance of items in group

I have been trying to search the forum for this, but I only came across this great tutorial by @rlkoshak

What I would like to do is to persist all my items in a group(temperature_set_points and GPIO_state) whenever they change, so that they keep their values on reboot.

Persist all my items in a group(temperature) whenever they change, and every 1h for graphing purposes.

Is there an easy way to do this? What persitance scheme should I use? Untill now I kept writing every item in a db4o file, but looking forward it would be easier to maintain groups instead.