In contrast to the homogeneous-type architecture, players within the tiered - or shard-type architecture connect to a layer of servers.

Fragmentation and reassembly are a costly affair and, though this is performed only by intermediate routers, it has severe impact on throughput.

The beauty of MongoDB's auto-sharding features is that it makes it very straightforward to go from a single server to a sharded cluster, often with little or no changes to application code required.