Consistent Hashing
This post is an AI-generated summary of the Medium article Advanced Algorithms Every Senior Developer Must Know: Part 2 — Consistent Hashing from Sourav Chaurasia. It is intended as a concise reference to the key ideas.
Consistent hashing solves one problem: when the number of servers changes, not every stored key should have to move to a different server. Here, a key can be a cached object, a user session, or a database record. If almost every key gets remapped after adding or removing one server, caches are invalidated and a lot of data has to be redistributed.