Understanding UUID v1 (Time-based)
UUID v1 incorporates a timestamp, clock sequence, and MAC address. It's deterministic and time-ordered.
Advantages:
- Time-ordered: Can be sorted chronologically
- Embedded timestamp: Useful for debugging
- Predictable: Same inputs produce same UUID
Disadvantages:
- Privacy concerns: May reveal MAC address
- Security: Can expose timing information
- Less random: More predictable than v4
Understanding UUID v4 (Random)
UUID v4 uses cryptographically secure random numbers. It's completely random and unpredictable.
Advantages:
- Maximum randomness: Highly unpredictable
- Privacy: No embedded information
- Security: Hard to guess or enumerate
- Most common: Widely used standard
Disadvantages:
- Not time-ordered: Cannot sort chronologically
- No embedded metadata: Less debugging info
When to Use UUID v1
- When you need chronological ordering
- Debugging scenarios requiring timestamps
- Internal systems where privacy isn't critical
- Legacy systems requiring v1 compatibility
When to Use UUID v4
- Public-facing APIs and web applications
- Security-sensitive applications
- When randomness is preferred
- Most modern applications (default choice)
Comparison Table
| Feature | UUID v1 | UUID v4 |
|---|---|---|
| Randomness | Low | High |
| Time-ordered | Yes | No |
| Privacy | Lower | Higher |
| Security | Lower | Higher |
| Use Case | Internal/Time-based | Public/Random |
Conclusion
Choose UUID v1 for time-ordered scenarios and UUID v4 for maximum security and randomness. For most applications, UUID v4 is the recommended choice.