What requirement does the BASE model support?
A. Atomic consistency
B. Isolated consistency
C. Eventual consistency
D. Immediate consistency
The correct answer and explanation is :
The correct answer is: C. Eventual consistency
Explanation (300 Words):
The BASE model is an alternative to the traditional ACID properties used in relational databases. BASE stands for Basically Available, Soft state, Eventually consistent, and it is commonly associated with NoSQL databases that are designed for high availability, scalability, and performance over strict consistency.
1. Basically Available
This means the system guarantees availability in terms of the CAP theorem. The system will always respond to requests, even if some parts of it are failing. However, the response might not always contain the most recent data.
2. Soft State
This implies that the system’s state may change over time, even without input. This is due to the eventual propagation of data updates across distributed systems.
3. Eventual Consistency
This is the key characteristic supported by the BASE model. It means that, given enough time without new updates, all nodes in the distributed system will eventually converge to the same final state. Unlike the ACID model, which provides immediate consistency, BASE allows temporary inconsistencies. This trade-off allows for better system availability and performance in distributed environments.
Why Not the Other Options?
- A. Atomic consistency: This is a characteristic of ACID systems, particularly focusing on transactions being all-or-nothing. BASE does not support this.
- B. Isolated consistency: This is not a standard term in database theory and seems to confuse two ACID properties — isolation and consistency.
- D. Immediate consistency: This is a hallmark of ACID systems. BASE does not guarantee immediate consistency, instead it favors eventual consistency for better scalability and availability.
In summary, the BASE model is designed for distributed, large-scale systems where availability and partition tolerance are prioritized, and eventual consistency is acceptable. Therefore, eventual consistency is the requirement that the BASE model supports.