Transaction Model
State consists of entities with values.
Execution consists entity read/write actions.
Groups of actions are transactions.
How to avoid concurrency anomalies:
- Def of anomalies: not equivalent to serial execution
- All transactions are well-formed and 2 phase
iff no concurrency anomalies (almost).
ACID properties:
- Atomicity, Consistency, Isolation, Durability
Many techniques: locks, logs, ....
Two-Phase commit for distributed system atomic commit.