Consistent Hashing ¶
Info
Consistent Hashing maps data to physical nodes and ensures that only a small set of keys move when servers are added or removed. It stores the data managed by a distributed system in a ring. Each node in the ring is assigned a range of data.
| Server | Token | Range Start | Range End |
|---|---|---|---|
| Server 1 | 1 | 1 | 25 |
| Server 2 | 26 | 26 | 50 |
| Server 3 | 51 | 51 | 75 |
| Server 4 | 76 | 76 | 100 |
The Consistent Hashing scheme described above works great when a node is added or removed from the ring, as in these cases, since only the next node is affected. For example, when a node is removed, the next node becomes responsible for all of the keys stored on the outgoing node. However, this scheme can result in non-uniform data and load distribution. This problem can be solved with the help of Virtual nodes.