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Comment by jordiburgos | Hacker News Reader

Please, do not use b6133fd6-70fe-4fe3-bed6-8ca8fc9386cd, I checked my database and I was using it already.

I always thought generating UUIDs at random was insane. I now only use LLMs. The prompt is: "generate a UUID. Make sure no one ever used it anywhere in their code or database. Check your work and think hard about each step. Do not output any reasoning or plain English, only th UUID itself".

You're welcome.

Actually asking ChatGPT this query led it giving me this UUID "550e8400-e29b-41d4-a716-446655440000" which happens to be a very common example UUID

The LLM is mechanistically unable to pick something actually random and outside of its training distribution, so... yep.

If you ask it to construct a UUID character by character you should get a somewhat random one, just because of temperature.

But all LLM output is token by token, which isn't too far from character by character in the case of a UUID. Why is this different? I do not know.

This actually worked well when I asked Gemini to generate a random color, character by character. I was getting Indigo/Electric Indigo a lot if I just asked for a random color on new sessions.

Actually, asking this multiple times to ChatGPT gives me different UUIDs every time, and it checked with a web search that they are not found in public data.

That's because of tokens (and temperature). You could piece back the tokens to parts of existing tokens in public data. And given enough iterations, GPT will probably start showing noticeable patterns (since it's not actually random).

I knew it, we're all getting the same cheap UUIDs and the good ones are reserved for the big dogs.

uuid.uuidv4() recently switched to "adaptive entropy" instead of "xmax entropy" in an effort to save costs on non-premium users.

You mean you’re not already entropymaxxing? n00b

I'm using 16b55183-1697-496e-bc8a-854eb9aae0f3 and probably some more too. I suppose if we all post our list here, then we can all check for duplicates?

We should all send our already-generated UUIDs to a shared database, we could just put it on Supabase with a shared username/password posted on HN, so we can all ensure that after generating a UUIDv4 locally, it's not used by anyone else. If it's in the database, we know it's taken.

It's a super simple mechanism, check in common worldwide UUID database, if not in there, you can use it. Perhaps if we use a START TRANSACTION, we could ensure it's not taken as we insert. But that's all easy, I'll ask Claude to wire it up, no problem.

But then I will claim I have already used all the UUIDs in my spreadsheets, and my lawyer will send cease&desist letters to every database.

A site previously posted here could be useful: https://everyuuid.com/

You can check https://everyuuid.com/ for collisions.

Full list here: https://everyuuid.com/

That UUID should have my name sticker on it. Don't your UUIDs have name stickers?

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