What is Sharding in MongoDB and how do Chunk Splitting and Shard Keys work?
Sharding is MongoDB's method for horizontal scaling across multiple servers to handle datasets larger than single-machine storage or throughput capacities.
Architecture components: • `mongos`: Query router that directs client operations to appropriate shards. • Config Servers: Store cluster metadata and routing mappings. • Shards: Individual replica sets that store chunks of the dataset.
A **Shard Key** determines data partitioning. A poorly chosen shard key (such as monotonically increasing IDs) creates 'hotspotting', where all writes hit a single shard.
// Enable sharding on database
sh.enableSharding("enterpriseApp");
// Shard collection using a hashed shard key to evenly distribute writes
sh.shardCollection("enterpriseApp.events", { customerId: "hashed" });A hashed shard key computes an MD5 hash of `customerId`, guaranteeing that write traffic is evenly distributed across all shards even if customer IDs are created sequentially.
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