Sharding is one of the most promising technologies for significantly increasing blockchain transaction throughput. However, as the number of shards increases, the ratio of cross-shard transactions in existing blockchain sharding protocols gradually approaches 100%. Since cross-shard transactions consume many times more resources than intra-shard transactions, the processing overhead of cross-shard transactions already accounts for the majority of the total overhead of the sharding system. There is a very large gap between the transaction throughput of the sharding system and its theoretical upper limit. In this article, we propose Estuary, a novel low cross-shard blockchain sharding protocol. Taking the state model as an entry point, Estuary designs a multi-level state model and state splitting and aggregation mechanism. It decouples the identity and quantity of state units, enabling transactions between users to be completed within one shard. Only when the state quantity for all shards of a user is insufficient a small number of cross-shard transactions are required. On this basis, we propose a community overlap propagation algorithm for sharding. It defines the users’ belonging coefficients of each shard and optimizes the state distribution so that the state distribution can better match the transaction characteristics between users. Finally, we develop an analysis framework for the sharding protocol and experiment with real Bitcoin transactions. The evaluation results show that compared to the state-of-the-art sharding protocol, Estuary reduces the ratio of cross-shard transactions by 88.54% and achieves more than 1.85 times the throughput improvement (92.98% of the theoretical upper limit).

中文翻译：

---

Estuary：一种基于状态分裂的低跨分片区块链分片协议

分片是显着提高区块链交易吞吐量的最有前途的技术之一。然而，随着分片数量的增加，现有区块链分片协议中跨分片交易的比例逐渐接近100%。由于跨分片交易比分片内交易消耗的资源多很多倍，因此跨分片交易的处理开销已经占到分片系统总开销的大部分。分片系统的交易吞吐量与其理论上限存在非常大的差距。在本文中，我们提出了 Estuary，一种新颖的低跨分片区块链分片协议。 Estuary以状态模型为切入点，设计了多层次的状态模型和状态分裂聚合机制。它将状态单元的身份和数量解耦，使用户之间的交易能够在一个分片内完成。只有当用户所有分片的状态量不足时，才需要进行少量的跨分片交易。在此基础上，我们提出了一种用于分片的社区重叠传播算法。它定义了每个分片的用户归属系数，并优化状态分布，使状态分布能够更好地匹配用户之间的交易特征。最后，我们开发了分片协议的分析框架并用真实的比特币交易进行实验。评估结果显示，与最先进的分片协议相比，Estuary 减少了 88.54% 的跨分片交易比例，实现了超过 1.85 倍的吞吐量提升（理论上限的 92.98%）。