🌏Key Takeaways
- 1Speed of light sets a hard floor: ~67ms minimum round-trip US East ↔ Europe, ~133ms to Asia-Pacific
- 2CRDTs (Conflict-free Replicated Data Types): data structures that merge automatically without coordination
- 3Data sovereignty: GDPR, data residency laws require data to stay in specific geographic regions
- 4Multi-region active-active requires careful conflict resolution: LWW, CRDTs, or operational transform
Systems That Span the Globe
When your system serves users on multiple continents, physics becomes the enemy. The speed of light introduces ~1ms per 200km of fiber. A round trip from New York to London takes at least 67ms, regardless of your optimization. Designing globally distributed systems means working within these constraints.
Conflict Resolution Strategies
Simplest strategy: timestamp each write, highest timestamp wins in case of conflict.
Easy but loses data: if two users edit simultaneously in different regions, one edit silently disappears.
Acceptable for: user profile updates, non-critical settings. Unacceptable for: collaborative editing, financial data.
Speed of Light Latency
67ms
NY ↔ London RTT
133ms
NY ↔ Tokyo RTT
280ms
London ↔ Sydney RTT
1ms
per 200km of fiber
Advantages
- •CRDTs provide automatic conflict resolution
- •Multi-region active-active serves users with low latency globally
- •Data sovereignty compliance is built into the design
Disadvantages
- •Physics limits latency (speed of light)
- •CRDTs are limited to certain data structures
- •Multi-region doubles infrastructure cost minimum
🧪 Test Your Understanding
Knowledge Check1/1
What are CRDTs?