CAP Theorem Variants
The CAP theorem states a distributed system can satisfy at most two of consistency, availability, and partition tolerance; its variants refine the trade-offs.
Purpose
To deeply understand CAP variants and precise formulations, guiding architectural trade-offs in distributed databases.
Mechanism
Network partitions (P) are unavoidable, so the real choice is between C and A. CP sacrifices availability for consistency (e.g., Spanner); AP sacrifices consistency for availability (e.g., Cassandra); CA exists only as a single node without partitions. Brewer 2012 correction: during partition it is latency, not total unavailability.
Use cases
- Distributed database selection
- Architecture trade-off analysis
- System design