Shard (database architecture)

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A database shard, or simply a shard, is a horizontal partition of data in a database or search engine. Each shard is held on a separate database server instance, to spread load.

Some data within a database remains present in all shards,^[a] but some appear only in a single shard. Each shard (or server) acts as the single source for this subset of data.^[1]

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