Confirmed UUID v4 collision detected in production database
By
mittermayr
Crusty in the right places. Worth the chew.
Summary
A developer reports a confirmed UUID v4 collision in their database, where a newly generated UUID matched one created a year ago. The collision was detected by a database constraint, ruling out a double-insert bug. The developer expresses shock and disbelief, noting the astronomical odds against such an event, and shares the specific UUID that collided (b6133fd6-70fe-4fe3-bed6-8ca8fc9386cd). They are using the popular 'uuid' npm package for generation.
Key quotes
· 3 pulledI know what you're thinking... and I still can't believe it, but...
This morning, our database flagged a duplicate UUID (v4). I checked, thinking it may have been a double-insert bug or something, but no.
The original UUID was from a record added in 2025 (about a year ago), and today the system inserted a new document with a fresh UUIDv4 and it came up with the exact same one: b6133fd6-70fe-4fe3-bed6-8ca8fc9386cd
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