Edward Capriolo: I can see your point. Indeed a very informative link.
As the link mentioned, the probability of ID collisions are very very rare.
Pasted from wikipedia:
"To put these numbers into perspective, the annual risk of someone being hit by a meteorite is estimated to be one chance in 17 billion, which means the probability is about 0.00000000006 (6 × 10−11), equivalent to the odds of creating a few tens of trillions of UUIDs in a year and having one duplicate. In other words, only after generating 1 billion UUIDs every second for the next 100 years, the probability of creating just one duplicate would be about 50%. The probability of one duplicate would be about 50% if every person on earth owns 600 million UUIDs."
With these probability, will it be necessary to make thing complex. Moreover, these IDs are often few in one hive session.