don't really need and implementation just an idea, and your solutions sound promising. Thank you !

PS

and no restriction is not 21 the whole range is between , as i wrote, 5-7 * 10^9 per id and the files are encoded and compressed to reduce space. the exaple i have written and the code is, again, just an example, simplification not to be used in in real case since this would be wasteful (considering space). but if i wrote the real thing i bet nobody would even look at the post. So i tried to be as simple (failed) as possible with my example. ++

cheers