Which of the following is considered an alternative to the two-phase commit for distributed transactions?

• A. Sagas
• B. Large distributed transactions: Google Spanner
• C. Eventual consistency
• D. CAP theorem: two of them can be achieved

Answer: (A)

Distributed transactions often rely on a coordination protocol like two-phase commit, which can lock resources across services and reduce availability in loosely coupled systems. Sagas offer another approach by breaking a long transaction into a sequence of local transactions, each committing independently. If any step fails, a set of compensating actions is invoked to undo the effects of previously completed steps. This yields eventual consistency and greater resilience in microservice architectures, making sagas a widely used alternative to two-phase commit. The other options don’t describe a practical coordination pattern: a globally distributed database like Google Spanner provides strong consistency but isn’t an alternate transaction coordination pattern; eventual consistency refers to the outcome rather than the coordination method; and the CAP theorem is a principle about trade-offs, not a transactional mechanism.