Nanosecond timestamp collisions are common

Re:Nanosecond timestamp collisions are common by dtech on Friday July 21, 2023 @05:53AM (#36811960)

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?

[ Parent | on HN ]

Re:Nanosecond timestamp collisions are common by wolf550e on Friday July 21, 2023 @06:36AM (#36812202)

You can hand out uuidv4 to clients without revealing anything.

[ Parent | on HN ]

Re:Nanosecond timestamp collisions are common by madsbuch on Friday July 21, 2023 @06:27AM (#36812151)

Entropy. You loose bits to a known source, which reduce entropy of the UUID.

[ Parent | on HN ]

Re:Nanosecond timestamp collisions are common by dralley on Friday July 21, 2023 @12:42PM (#36816080)

128 bits is a lot of entropy to go around, though.

[ Parent | on HN ]

Re:Nanosecond timestamp collisions are common by dtech on Friday July 21, 2023 @03:37PM (#36818534)

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.

[ Parent | on HN ]

Re:Nanosecond timestamp collisions are common by andersa on Friday July 21, 2023 @02:24PM (#36817505)

Anyone who can see the uuidv7 can determine at what time it was generated. You might not want that for things exposed to users.

[ Parent | on HN ]