Sharding & Partitioning
Your shard key is a multi-year commitment — choose wrong and no amount of hardware fixes it. Hash vs range vs compound keys, re-sharding without downtime, cross-shard query costs, and how Instagram, Vitess, and Notion partition billions of rows.
This study guide is part of the full calibration library.
Staff interviews are decided on nuance — tradeoff framing, ownership boundaries, and failure anticipation. This study guide covers the depth that separates Senior from Staff+.
What's inside this study guide
Practice & Reference
- •Why This Matters
- •The 60-Second Version
- •How Sharding Works
- •Partitioning Strategies
- •Shard Key Selection
- •Logical vs. Physical Shards
- •Re-Sharding: The Operation Nobody Wants
- •Cross-Shard Queries
- •Sharding Beyond the Database
- •The Numbers in Context
- •How This Shows Up in Interviews
- •Visual Guide: Strategy Selection
- •In the Wild
- •Staff Calibration
- •Practice Drill
- •Where This Appears