Blockchain's decentralization, transparency, and tamper-resistance properties have facilitated the system's use in various application fields. However, the low throughput and high confirmation latency hinder the widespread adoption of Blockchain. Many solutions have been proposed to address these issues, including first-layer solutions (or on-chain solutions) and second-layer solutions (or off-chain solutions). Among the proposed solutions, the blockchain sharding system is the most scalable one, where the nodes in the network are divided into several groups. The nodes in different shards work in parallel to validate the transactions and add them to the blocks, and in such a way, the throughput increases significantly. However, previous works have not adequately summarized the latest achievements in blockchain sharding, nor have they fully showcased its state-of-the-art. Our study provides a systemization of knowledge of public blockchain sharding, including the core components of sharding systems, challenges, limitations, and mechanisms of the latest sharding protocols. We also compare their performance and discuss current constraints and future research directions.

翻译：区块链的去中心化、透明性与防篡改特性使其在众多应用领域得到广泛采用。然而，低吞吐量和高确认延迟阻碍了区块链的大规模普及。针对这些问题，学界已提出多种解决方案，包括第一层解决方案（或称链上方案）与第二层解决方案（或称链下方案）。在现有方案中，区块链分片系统展现出最优的可扩展性——其将网络节点划分为若干组，不同分片中的节点并行验证交易并打包至区块，从而显著提升系统吞吐量。然而，既有研究尚未充分总结区块链分片技术的最新进展，亦未完整呈现其前沿发展态势。本研究系统梳理了公有区块链分片的知识体系，涵盖分片系统的核心组件、技术挑战、局限性以及最新分片协议的运行机制。通过对比不同协议的性能表现，我们进一步探讨了当前技术瓶颈与未来研究方向。