Table of Contents
Consistent hashing is a technique used in distributed systems to evenly distribute data across multiple nodes. It minimizes data movement when nodes are added or removed, making it ideal for NoSQL databases that require scalability and fault tolerance.
Understanding Consistent Hashing
Consistent hashing assigns each data item and each node a position on a hash ring. Data is stored on the node whose position on the ring is closest to the data’s hash value. When nodes are added or removed, only a small portion of data needs to be redistributed.
Calculations in Consistent Hashing
The core calculation involves hashing node identifiers and data keys using a uniform hash function. The position on the ring determines data placement. When a new node joins, it takes over responsibility for a segment of the ring, redistributing only the data within that segment.
Applications in NoSQL Databases
Many NoSQL databases implement consistent hashing to improve scalability and availability. Examples include Cassandra, DynamoDB, and Riak. These systems use the technique to distribute data evenly and handle node failures gracefully.
- Distributed data storage
- Load balancing
- Fault tolerance
- Scalability