Sharding

Sharding horizontally partitions a vector index across multiple machines so that each shard holds a subset of the total vectors. At query time, the search fan-out hits all shards in parallel and results are merged by a coordinator. Sharding enables a vector database to scale beyond what a single machine's RAM can hold and to increase query throughput proportionally with the number of shards. The shard count must be chosen carefully because re-sharding after initial deployment is costly.