Consistent Hashing Basic

# Core Concepts of Consistent Hashing Traditional hashing uses the modulo operator: `hash(key) % N`, where N is the number of server nodes. This behaves poorly when servers are added or removed, since **almost all keys** re-map to new servers, causing a cache stampede. Consistent hashing solves this problem by using a shared circular hash ring (e.g., from 0 to $2^{32}-1$). --- ## 1. Step-by-Step Distribution 1. **Hash the Servers**: Hash server IPs and map them to positions on the ring. 2. **Hash the Keys**: Hash client keys and map them on the same ring. 3. **Route Requests**: To locate a key's server, travel clockwise from the key's position until you hit the first server node. --- ## 2. Virtual Nodes (V-Nodes) To prevent hot spots (uneven distribution), we hash each physical server multiple times using offsets (e.g., `Node1#1`, `Node1#2`). This guarantees a highly uniform key distribution across all active physical servers.