Glossary term
What is Consistent hashing? Meaning for developers
In System Design
Places keys and servers on a ring so few keys move when servers change. Example: Adding a cache server moves only ~1/N of keys.
Learn it properly · System DesignLesson 26: Consistent Hashing, Visually ExplainedAdd a fifth cache server to hash(key) % 4 and 80% of your keys move — the hit ratio collapses and the database falls over. How the hash ring moves only ~1/N of keys, why virtual nodes even out the load, and the alternatives.In System Design Case Studies 2
Place nodes and keys on a ring so that adding or removing a node moves only a small share of the keys.
Learn it properly · System Design Case Studies 2Lesson 1: Design a Key-Value Store (Like Redis or Dynamo)A write-ahead log and snapshots on one node, then a consistent-hash ring, N/R/W quorum and version vectors across many.