Inderpreet's last post on persistence database was interesting. He tried RRD4J. Thanks for sharing this Inderpreet.
I tried MongoDB on the Pi. The problem for me is performance. The Pi slowed to a crawl when I had MongoDB on the same Pi as OpenHAB. It would be nice to have an atomic solution where the database lived on the same Pi as OpenHAB. Just wondering if others can shared what they've tried and how it effected the performance of the OpenHAB UI.
Ideally, I'd like to have a DB like MongoDB and use a good data visualization program - something like Pentaho maybe - to chart energy usage data along with indoor/outdoor temperature, humidity, etc..