When to Shard & Choosing a Shard Key
When to Shard & Choosing a Shard Key
HardDatabases0% accepted
A single Postgres instance can no longer hold your write volume. Explain horizontal sharding, how to pick a shard key, and the pain it introduces. Cover: range vs hash sharding, hot-spot/celebrity problems from a bad key, cross-shard joins and transactions, and re-sharding cost.
Approach
Shard when one node can't handle the data/writes. Pick a key with high cardinality and even distribution (hash) to avoid hot shards. Cross-shard joins/transactions get hard; re-sharding is expensive — choose the key carefully.
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