Consider switching to an actual DB

[V-FEXrt]

https://docs.python.org/2/library/sqlite3.html

[PathogenDavid]

One nice feature of using a plain text file for the store is that you could store it in Git if you wanted to share it with a team.

IMO, the power on SQLite would be wasted on a project like this. You could just serialize the map to JSON or something though.