The 32 million keys in your solution must be sequential, which means it can't do 32 million arbitrary keys, which is what others thought you meant.
Why would you need arbitrary keys? Do you need to go through the entire range?
target= 1000000000
range=1:200000000
Add and subtract random or arbitrary quantities from the target and you get a list of targets.
To these targets you apply a binary sequence of the size you want and you obtain a database distributed in multiple sections of the range.
You can also make jumps in the sequence, every 3 keys or however much you want.