If i wanna make a chart/log for my temperature and other simple stuff what is the best option ?
mapdb rrd4j mysql mitt etc…
so many options i get confused 
using oh2 with rfxcom zwave ihc verisure
mapdb only stores the last value of an item. Therefore not an option.
mysql and rrd4j are both possible, but mysql is a little more complicate to install.
I vote for rrd4j!
Some notes for rrd4j: rrd4j only stores numbers. But that’s of course ok if you only want to store temperature data. And rrd4j summarizes data after a certain period of time. So if you want to know which temperature exactly there was at christmas 2008, rrd4j will not give to the exact value.
That descrition is correct, however RRD4J does only summarize data in the timeframe in which you want it to. By using the default setting you are selecting such a setting.
You can set RRD4J to persist the value for each minute during the last X days if you want to. The main feature is that the DB will not get bigger.