Comment by ComputerGuru | Hacker News Reader

Comment by ComputerGuru | Hacker News Reader

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I haven’t been able to find a case for this because ids either need to be unique or they’re not going to be large. If they’re unique, I’m using uuid or ulid (uuidv7 of tomorrow) as the sortable primary key type to avoid conflicts without using the db to generate and maintain sequences.

Where do you have unique ids that aren’t the primary key? I would be more interested in a retrospectively unique truncated encoding for extant ulid/uuid; ie given that we’ve passed timestamp foo, we know that (where no external data is merged) we only need a bucketed time granularity of x for the random component of the id to remain unique (for when sortability is no longer needed).

Or just more generally a way to convert a ulid/uuidv7 to a shorter sequence if we are using it for external hash table lookups only and can do without the timestamp component.

The idea is that you encode and decode database IDs with this. You wouldn't save them separately unless you were using it for a purpose other than shareable "identifiers" which don't leak significant amounts of database state. Imagine something like a link shortener where you want to provide a short link to users, but don't want it to just be a number.

My point was that this only encodes numbers and you wouldn’t use numbers as primary keys for the reasons outlined.

These leak the state just as much. They're reversible back to integers.

> Where do you have unique ids that aren’t the primary key?

For things that need public IDs, I always generate and store uuid4s* to avoid leaking database state or anything like that. Even uuid7 leaks creation timestamps. It's cheap and easy to map public IDs to/from PKs at the API boundaries.

* possibly encoded as something nicer like base64 for APIs or URLs

I’m currently using sqids as slugs to have a shorter url than just using my uuid primary key

Why would the number the sqid converts to not be your primary key, though? Why do you need the uuid at all?

why is ulid the uuidv7 of tomorrow?

Uuidv7 is inspired by ulid.

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