Data

Hot Shard

One partition receiving a disproportionate share of traffic, usually from a celebrity or whale key.

Why interviewers ask about it

Consistent hashing does not fix it - it distributes keys, not traffic. Fixes are compound keys, dedicated shards, or caching the hot key.

The column determining which shard a row lives on.

Map keys and nodes onto a ring; a key belongs to the first node clockwise. Adding a node moves only ~1/N of keys.

This term is part of the free System Design interview preparation module - browse the full glossary for every definition.