Strong Consistency
Table of Contents
1. Overview
- Definition of Strong Consistency: A consistency model in distributed systems ensuring that all nodes see the same data at the same time.
- Key Features:
- Guarantees immediate visibility of updates across all users and nodes.
- Prevents anomalies such as reading stale or outdated data.
- Use Cases:
- Suitable for applications requiring strict data accuracy (e.g., banking systems, online transactions).
- Comparison with Other Models:
- Strong consistency vs. eventual consistency: Strong consistency prioritizes immediate correctness over availability.
- Trade-offs often involve performance cost and potential system throughput reduction.
2. Variations via Quorum
with the following:
- W : write quorum
- R : read quorum
- N : total nodes
| Configuration R | Description |
|---|---|
| R = 1, W = N | fast reads |
| R = N, W = 1 | fast writes |
| W + R > N | strong consistency guaranteed |
| W + R <= N | strong consistency not guaranteed |