Type Alias: ShardHash

> ShardHash = (key, shardCount) => number

Horizontal sharding: route a key (typically a tenant id) to one of a fixed set of database clients. The mapping is deterministic — the same key always lands on the same shard across processes and restarts — so a tenant's data always lives on the same database.

Unlike the per-tenant pool, shard clients are long-lived and shared by many tenants; nothing is evicted. Wire it with prismaPlugin({ shards }).