Opensteetmap is the crowdsourced mapping of the planet and can be accessed at https://opensteetmap.org The map data is freely downloadable and can be hosted locally for any purpose whatsoever under GPL license. Map data is downloadable in multiple archive formats like pbf (Protocolbuffer Binary Format) and others. OSM's internal data model is represented as shown in the ER diagram above, but when it's imported from the PBF, it has to be efficient, fast and easy to use. Primarily, OSM databases can either be, Snapshot or Historical Snapshot databases don't contain historical infromation (for instance, how a river changed it's course of the years or how landuse of a forested land changed over the year) whereas, Historical database contains this information. Naturally, historical databases are much more complex and requires more effort. Various parameters on how to judge various data stores are, Updatability Transactibility Concurrent Read/Writability Snapshot/Historical...
Universe from my perspective..