Concurrency Control
Four choices:
- Primary copy: e.g., read: {{a}} write: {{a}}
- Read-one-write-all: e.g., read: {{a}, {b}, {c}} write: {{a, b, c}}
- General quorum: e.g., read: {{a}, {b, c}} write: {{a, b}, {a, c}}
- Majority quorum (1 vote each): e.g., read & write: {{a, b}, {b, c}, {a, c}}