Database / ValKey Interview questions
How does Valkey Cluster achieve horizontal scaling through hash slots?
Every key is mapped to one of 16384 fixed slots using CRC16(key) mod 16384, or the portion of the key inside curly braces when a hash tag like {user1000}.profile is used to force related keys into the same slot.
Each slot is owned by exactly one primary node at a time, and the cluster distributes ownership of the full slot range across all primaries so no single node has to hold the entire dataset.
flowchart LR
K[Key] --> H["CRC16(key) mod 16384"]
H --> S[Slot 0-16383]
S --> N1[Primary Node A]
S --> N2[Primary Node B]
S --> N3[Primary Node C]
N1 -.MOVED redirect.-> Client
Scaling out simply means assigning some existing slots to a newly added node and migrating their keys, spreading both storage and command load across more machines without any application code changes.
A key's cluster slot is computed as...
When a client contacts a node that doesn't own a requested key's slot, it receives...
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