See how to use a hash table. The example uses a small hash table that works with std::strings as key and any data as member. (The article, demo project, and source code were updated.) By Rex Schilasky.
MegaMap is a Java implementation of a map (or hashtable) that can store an unbounded amount of data, limited only by the amount of disk space available. Objects stored in the map are persisted to disk. Good performance is achieved by an in-memory cache. The MegaMap can, for all practical reasons, be thought of as a map implementation with unlimited storage space.