I don’t think its a private api, just part of how the Sqlite3 virtual machine works. You can read about rowid here. Basically it exists, and you can use it to index things, but you can’t look at how it works. (as far as my limited knowledge of the sqlite public api goes anyway)
In most cases the rowid is the primary key, (although this isn’t always true), the only problem is that sqlite internally doesn’t actually dispatch the callback (what sends data back to Beam) until after the row has been destroyed.
There actually is commit and rollback hooks (described here) but that would add more complexity to the NIF than i would ideally give it.
