UUIDs (Universally Unique Identifiers) are standardized 128-bit identifiers used to uniquely identify information in computer systems. Here’s a brief comparison of UUID v4, v5, and v7:

UUID v4

  • Random-based: UUID v4 is generated using random numbers.
  • Uniqueness: High probability of uniqueness due to randomness.
  • Use case: Suitable for most general-purpose applications where uniqueness is required without a need for determinism.
  • Example: 550e8400-e29b-41d4-a716-446655440000

UUID v5

  • Name-based (SHA-1): UUID v5 is generated using a namespace identifier and a name, hashed with SHA-1.
  • Deterministic: The same namespace and name will always produce the same UUID.
  • Use case: Useful when you need to generate the same UUID for the same input (e.g., generating UUIDs from URLs).
  • Example: 3c4e2b84-6414-5b6b-8a2b-4d6e1e4b6c8a

UUID v7

  • Time-ordered: UUID v7 is a new proposed standard that combines a timestamp with random bits.
  • Uniqueness and ordering: Provides both uniqueness and time-ordering, making it useful for distributed systems where order matters.
  • Use case: Suitable for scenarios where you need unique identifiers that can also be sorted chronologically.
  • Example: Not yet standardized, but would look similar to other UUIDs with a time-based component.

Comparison Table

Feature UUID v4 UUID v5 UUID v7
Generation Type Random Name-based (SHA-1) Time-ordered
Uniqueness High Deterministic High
Use Case General-purpose Consistent UUIDs Chronological sorting
Example 550e8400-e29b-41d4-a716-446655440000 3c4e2b84-6414-5b6b-8a2b-4d6e1e4b6c8a Not yet standardized
Standardization RFC 4122 RFC 4122 Proposed
Namespace N/A Defined (e.g., DNS, URL) N/A

Summary

  • v4: Random, high uniqueness, general-purpose.
  • v5: Deterministic, name-based, useful for consistent UUIDs from the same input.
  • v7: Time-ordered, combines uniqueness with chronological sorting, useful for distributed systems.

Choose the version based on your specific requirements for uniqueness, determinism, and ordering.