hash(key) % N Versus Consistent Hashing
TradeoffSeniorStaffUpdated
Sharding 100GB of session data across 10 cache nodes, with occasional node additions/removals.
Short answer: Consistent hashing. Modulo remaps ~all keys when N changes.
The Two Options
A
hash(key) % N
B
Consistent hashing
Drill This: Your Pick First
The Better Pick
Option B
Consistent hashing
Modulo remaps ~all keys when N changes. Consistent hashing moves only ~1/N of keys, preventing cache stampedes during scaling.
When the Other One Wins
hash(key) % N
If the node count is truly fixed forever, modulo is simpler and has perfectly uniform distribution.