For a first guess, if there were 5 writing dbs, each could write every 5th id, starting at a different index (0,1,2,3,4).
You'd end up with globally unique ids, and as long as your writes were (approx.) evenly distributed, all 5 sequences would be (approx.) close to each other.
Who knows, they might have 100 writable dbs, with only 70% up at any point in time, meaning only 70% of all integers are actually used.. anyway, I don't know, I can just imagine them doing something like this if they wanted certain things from the system.
You'd end up with globally unique ids, and as long as your writes were (approx.) evenly distributed, all 5 sequences would be (approx.) close to each other.
Who knows, they might have 100 writable dbs, with only 70% up at any point in time, meaning only 70% of all integers are actually used.. anyway, I don't know, I can just imagine them doing something like this if they wanted certain things from the system.