“Scale out the management of a large number of domain objects by grouping them into shards based on unique and stable object properties.”

The Domain Object pattern gives you the ability to wrap the domain’s state in small components that can, in principle, be distributed easily across a cluster of network nodes in order to provide the resources for representing even very large domains that cannot be held in memory by a single machine. The difficulty then becomes how to address the individual domain objects without having to maintain a directory that lists every object’s location—such a directory could easily reach a size that is impractical to hold in memory.

The Sharding pattern places an upper bound on the size of the directory by grouping the domain objects into a configurable number of shards—the domain is fractured algorithmically into pieces of manageable size. The term algorithmically means the association between objects and shards is determined by a fixed formula that can be evaluated whenever an object needs to be located.

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