Init guide environment...
Every piece of data (key) is hashed into an integer (e.g., using SHA-256) and mapped to a point on the conceptual ring.
Servers (nodes) are hashed using their IP or ID onto the exact same conceptual ring alongside the data.
To find the server for a data key, walk clockwise around the ring from the data's hash value until you hit the first server.
To prevent uneven load distribution, each physical server is mapped to multiple 'virtual' points on the ring to balance the segments.
How finding a node works.
flowchart TD
Client(["Client API Request"]) --> HashKey["Hash('user_123')"]
HashKey --> Ring{Hash Ring}
subgraph Hash Ring space
Ring --> Walk[Walk Clockwise]
Walk --> NodeMatch[First Node Found]
end
NodeMatch --> S1[(Server A)]
NodeMatch -.->|If A fails| S2[(Server B)]
style Client fill:transparent,stroke:#22d3ee,color:#ffffff
style HashKey fill:#12161f,stroke:#334155,color:#ffffff
style Ring fill:transparent,stroke:none,color:#c084fc
style Walk fill:#12161f,stroke:#334155,color:#ffffff
style NodeMatch fill:transparent,stroke:#4ade80,color:#4ade80
style S1 fill:transparent,stroke:#334155,color:#ffffff
style S2 fill:transparent,stroke:#f472b6,color:#94a3b8
Visualize data assignment and node scaling
| Algorithm | Cost to Add/Remove Node (K = keys, N = nodes) | Uniform Load Distribution | Complexity | Best For |
|---|---|---|---|---|
| Standard Hashing | O(N) data moves | ✗ No (uneven gaps) | Static fixed pools (rare) | |
| Consistent Hashing | O(K/N) data moves | ✗ No (uneven gaps) | Dynamic scaling, caching | |
| Consistent + Virtual | O(K/N) data moves | ✓ Yes | Cassandra, DynamoDB, Riak |