Quorum has a feature called private contracts in which a contract is executed only on specific nodes meaning that the data of the transaction is encrypted and it can be encrypted only on specific nodes, defined by the contract. The state model is spited into two major categories:
- public state is validated by each node and made consistent on the whole network
- private state is validated only on specific nodes: only if the contract is in party with the node.
From a practical point of view it is a special kind of sharding. As private contracts can not call a public ones, the public state is always consistent. However, considering the private contracts, there might be some unexpected result, if the similar logic is deployed with different parties and they confidently call the same private contract, it can be pretty much questionable how the consensus is created.