Hierarchical Execution of Cross-Shard Transactions with Multiple Smart Contract Functions

A sharding framework has been proposed by Ethereum 2.0, and each shard can execute transactions requested by users, so the number of transactions dealt with by the shard-based blockchain grows as the number of shards increases. Dealing with cross-shard transactions, however, is a major hindrance to blockchain performance, because each such transaction requires cooperation among different shard validators in the network. Given this background, this paper proposes a novel cross-shard architecture in which smart contract functions in different shards are called in a hierarchical manner so as to dramatically reduce the interactions among different shard validators.