1.6 BASE

1. What Is BASE?

• An extension of AP theory.
  • It guarantees eventual consistency rather than strong consistency. That is, because failures are unavoidable, I allow data to be different during this period, but after this period the data needs to be consistent.
  • Availability is obtained by sacrificing strong consistency. When a failure occurs, partial unavailability is allowed, but core functions must remain available.

1.1. Basic Availability

• Basic availability.
• The system may be temporarily unavailable but will recover quickly afterward.

1.2. Soft-state

• Soft state.
• An intermediate state between a “stateful” and a “stateless” service, as described in Distributed-System Service State. In other words, to improve performance, we can let a service temporarily retain some state or data, and that state and data do not have to be strongly consistent.

1.3. Eventual Consistency

Eventual consistency. The system is inconsistent for a short period of time, but the data will eventually become consistent.

2. Flexible Transactions

• Rigid transaction: fully follows the ACID specification.
• Flexible transaction: a transaction that satisfies BASE theory is a flexible transaction.

2.1. How to Implement Flexible Transactions

• The core approach is to asynchronously execute distributed processing tasks through a message queue. If the transaction fails, a manual retry correction process can be initiated.
• Distributed Transaction Solution: Saga

3. References

• Distributed Theory (2) - BASE Theory - Juejin
• Microservice Architecture: Eventual Consistency + Transaction Compensation | Magic Mirror’s Technical Notes
• Definition and Classification of Flexible Transactions - Ant Group Financial Technology