That makes me happy. 
https://docs.openhab.org/addons/persistence/mapdb/readme.html
See Design Pattern: Group Based Persistence and https://docs.openhab.org/configuration/persistence.html#persistence-extensions-in-scripts-and-rules
tl;dr, I use MapDB for restoreOnStartup to restore all my Items to whatever state they were in when OH went down or the .items file was saved. And I do so for all of my Items. When you make calls to the persistence methods on an Item, you can specify which persistence engine you want to use to pull the result from. In this case I’m pulling the data from MapDB instead of InfluxDB because I know I store ALL of my Items in MapDB but only those Items I want to chart in InfluxDB. I could set MapDB as my default persistence engine and not pass in the name but I like to be explicit where I’m pulling the data from.