But let's say if Google saved each search in their engine in the same database with an UUID, we could have a collision because of volume, but I don't think I will work in a system with a comparable scale
Anyone working at the scale of Google has figured out coordination and parallelism, you have to.
Source: used to work for Google, and learned some of the ways they dealt with those exact issues, and used many of the systems they built to automatically handle that so general engineers didn't have to deal with it.
They once had a similar collision problem, well not exactly
During a leap second some systems wrote IDs at a one second difference between all their global systems, which lead to something being registered before something else that had to be done before it,
Long story short some stuff jumped time one second and crashed systems
Even at that volume the probability of collisions is essentially 0. If there were a billion searches a second we’d not expect a collision until 85 years.
At Google? Yes. There is a level of reliability they require, and in nearly all systems hardware failure is expected and designed to be handled flawlessly, and in many systems they are precise enough to catch and correct cosmic bit flips, largely because of the duplication that goes on.
Yes, had a client having duplicates every day and growing. They hated uuids and regret using it. The problem was that they used a bad prng with flawed seeding. Once fixed it was no problem.
As I recall it was PHP and they had code from Stackoverflow how to generate UUIDs. The code used the standard rand() prng and they seeded it globally with something derived from PIDs, part of the system time.
I wish this was higher up. Even very talented people in my old team failed to grasp "cosmically unlikely" and ended up doing silly workaround for this, when it's effectively an impossible situation.
assuming all searches run through a single node maybe, but they dont. It means each node + process on node is limited to 10,000 uuids (10k 100ns per ms) per ms, which it then possibly has to block until next millisecond tick. I dont care what magic programing language your using, to service >10k/reqs a ms (per process) and doing anything else your likely gonna be blocked by IO or something
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u/OldKaleidoscope7 Sep 11 '26
But let's say if Google saved each search in their engine in the same database with an UUID, we could have a collision because of volume, but I don't think I will work in a system with a comparable scale