Scalability is often considered the "Achilles' heel" of blockchain technology. With a traditional chain-based structure, blocks cannot be generated concurrently, thus limiting the throughput and slowing transaction confirmation. Recently emerged graph-based blockchains generally excel in on-chain performance but are weaker in structural flexibility, which is essential for off-chain or cross-chain scaling. In this paper, we propose Fractal Ledger, a novel blockchain model to scale out the ledger in a fractal manner. Fractal Ledger is comprised of fractal units that synthesize both chain and graph structure. Through conversions and interactions of fractal units, Fractal Ledger can share the advantages of both types of blockchains and offer scalability in structure and storage. We introduce the deduction mechanisms for flexible structure scalability and a three-directional folding scheme of lossless on-chain data compression for storage scalability. Our experimental results reveal the effectiveness of Fractal Ledger in enhancing structure and storage scalability.

Traditional blockchain systems still struggle with limited throughput, particularly those compatible with EVM, which are crucial in many blockchain applications. One of the main reasons arises from serial execution, which doesn’t exploit parallelism in transaction execution. Although some recent literature introduced concurrency control mechanisms to execute transactions in parallel, they do not work efficiently in real-world blockchains where proposers and validators have different execution contexts, which means varying execution deterministic levels and execution quantities.

Abstract Blockchain has attracted tremendous attention from both the academia and the capital market. The insertion of data in a blockchain known as anchoring makes data verifiable and independently auditable and has many potential applications. The objective of this paper is to introduce a dynamic cross-chain anchoring framework for snapshotting users’ data into multiple public blockchains with the help of smart contracts. This paper starts by proposing the framework and depicting the components and workflow. Second, we design a target chain selection algorithm that combines the states of different blockchains. Using the algorithm, users can dynamically select a suitable public blockchain for anchoring tasks. Third, the virtual chain protocol is presented and achieves data anchoring orderly and integrally. Analyzation and evaluation show that the framework can enhance user experience, robustness and performance.

Abstract The inability to scale is one of the most concerning problems looming in blockchain systems, where every node has to store all contents of the ledger database locally, leading to centralization and higher operation costs. In this paper, we propose a model named virtual block group (VBG), which aims at addressing the node storage scalability problem. Adopting the VBG model, each node only needs to store part of block data and saves the VBG storage index to distributed hash table by taking block data as a resource, thus improving the query efficiency of block data. With the incentive mechanism of block data storage, and the storage verification and audit mechanism of block data, the security and reliability of block data storage can be ensured. The analysis and calculation show that this model saves hard drive storage space of the node to a greater extent with a shorter time of requesting block data, in the premise of ensuring secure and reliable block data. Compared to other technologies such as sharding, our model does not change the consensus mechanism or the network topology and retains the reliability and security of the original blockchain system.