> For the love of God just use SQLite if you want an embedded database for structured data, even if it's just eav. If you just need key/value there are battle-tested, well maintained options.

You can also use the SQLite Disk Btree as a key-value data store. I've just implemented a solution that does so in C++ with a LevelDB-like api.

You should use the backend Btree api (the same the VDBE/SQL engine uses to store stuff) and create 'tables' the SQLite uses for indexes. The integer-key based is used for ordinary SQL table .. (1 PK = 1 Record) and the blob-key type, where its agnostic about whats on the key. (Thats the one you use to create the KV store)

There are a couple of details, to make it right, but its not that hard, and its a great solution.