documentdb-sharding

Horizontal sharding (partitioning) for Azure DocumentDB collections — when to shard vs stay single-shard, how to pick a shard key for read-heavy vs write-heavy workloads, the logical/physical shard mental model, scaling out vs scaling up, hot-partition diagnosis, and the `sh.shardCollection` / `sh.reshardCollection` commands. Use when deciding whether to shard a collection, choosing or changing a shard key, sizing a cluster, or troubleshooting uneven storage / throughput across physical shards.