Sure it is. You just need a one to one function from person to [0, eight billion]. Use that as your array index and you're golden. 8 GB is overkill, really, you could pack some boolean datum like "is over 18" into bits within the bytes and store your database in a single gigabyte.

Writing your mapping function would be tricky! But definitely theoretically possible.

I'm old enough to have built systems with similar techniques. We don't do that much anymore since we don't need to, but it's not rocket science.

We had spell checkers before computers had enough memory to fit all words. They'd probabilistically find almost all incorrect words (but not suggest corrections). It worked fine.

meh. memory address is the ID

Airline booking numbers used to just be the sector number of your booking record on the mainframes HDD.

That’s why they were constantly recycled?

My jaw just hit the floor. What a fascinating fact!

source?

This is such a simple scheme.

I wonder how they dealt with common storage issues like backups and disks having bad sectors.

They're likely record based formatting rather than file based. At the high level the code is just asking for a record number from a data set. The data set is managed including redundancy/ECC by the hardware of that storage device.