alt Hacker News> The solution is not to come up with yet another artificial identifier but to come up with better means of identification taking into account the fact that things change.
I think artificial and data-less identifiers are the better means of identification that takes into account that things change. They don't have to be the identifier you present to the world, but having them is very useful.
E.g. phone numbers are semi-common identifiers now, but phone numbers change owners for reasons outside of your control. If you use them as an internal identifier, changing them between accounts gets very messy because now you don't have an identifier for the person who used to have that phone number.
It's much cleaner and easier to adapt if each person gets an internal context-less identifier and you use their phone number to convert from their external ID/phone number to an internal ID. The old account still has an identifier, there's just no external identifier that translates to it. Likewise if you have to change your identifier scheme, you can have multiple external IDs that translate to the same internal ID (i.e. you can resolve both their old ID and their new ID to the same internal ID without insanity in the schema).
> I think artificial and data-less identifiers are the better means of identification that takes into account that things change. They don't have to be the identifier you present to the world, but having them is very useful.
If the only reason you need a surrogate key is to introduce indirection in your internal database design then sequence numbers are enough. There is no need to use UUIDs.
The whole discussion is about externally visible identifiers (ie. identifiers visible to external software, potentially used as a persistent long-term reference to your data).
> E.g. phone numbers are semi-common identifiers now, but phone numbers change owners for reasons outside of your control. If you use them as an internal identifier, changing them between accounts gets very messy because now you don't have an identifier for the person who used to have that phone number.
Introducing surrogate keys (regardless of whether UUIDs or anything else) does not solve any problem in reality. When I come to you and say "My name is X, this is my phone number, this is my e-mail, I want my GDPR records deleted", you still need to be able to find all data that is related to me. Surrogate keys don't help here at all. You either have to be able to solve this issue in the database or you need to have an oracle (ie. a person) that must decide ad-hoc what piece of data is identified by the information I provided.
The key issue here is that you try to model identifiable "entities" in your data model, while it is much better to model "captured information".
So in your example there is no "person" identified by "phone number" but rather "at timestamp X we captured information about a person at the time named Y and using phone number Z". Once you start thinking about your database as structured storage of facts that you can use to infer conclusions, there is much less need for surrogate keys.