I'd like to know what rodb is. Columnar DB? Columnar DBs often beat "big data" -I've beaten decent sized spark clusters in one thread of J.
Or are you talking about just rolling your own format to dump your data into? I've done that, but I'd still appreciate if I could use something that someone else had put the thought into. (Something like "cdb" by Daniel J. Bernstein, but that's an old 32-bit library that's limited to 4 GB files.)