4 ms·

I feel like v7 is almost a strictly better v4. Assuming you can generate a v7 (you have a time source), what are the disadvantages?

• madsbuch 3y ago
  Entropy. You loose bits to a known source, which reduce entropy of the UUID.
  • dralley 3y ago
    128 bits is a lot of entropy to go around, though.
  • dtech 3y ago
    I do feel 74 bits per second is enough though. That would require 2^(74/2) = 137 billion UUIDs generated in a single second for a 50% chance of a single collision.
• wolf550e 3y ago
  You can hand out uuidv4 to clients without revealing anything.
• andersa 3y ago
  Anyone who can see the uuidv7 can determine at what time it was generated. You might not want that for things exposed to users.