当今社会商品质量问题频繁发生，供应链溯源作为有效监管手段之一变得十分重要。传统供应链溯源方法存在数据易篡改、数据孤岛等问题，目前较为流行的是通过区块链技术去中心化存储、节点共识等特点解决上述问题。但区块链由于单个节点性能有限、链式结构等因素，存在查询效率低、查询方式单一的问题。针对区块链查询中存在的问题，本文提出基于数据分片的区块链溯源查询优化方法，并通过Hyperledger Fabric平台完成验证与应用，具体工作如下：

针对区块链查询效率低的问题，本文提出基于数据分片的区块链溯源查询优化方法，上传的数据达成共识并广播发送后，各节点根据数据摘要将数据存储到本地对应分片中，链上只存储溯源信息摘要。进行查询时，通过链码将待查询事务根据事务摘要分发给多个节点并行查询，减少单节点查询的事务数量。节点内部根据事务范围，调用多个进程在本地对应分片并行查询，提高查询效率。针对区块链查询方式单一的问题抽象出4种查询请求：查询某时间点某产品位置信息、查询某时间段内某个体所经手的所有产品、查询某产品所有原材料信息、查询某原材料所有成品信息，并结合基于数据分片的区块链溯源查询优化方法给出具体算法流程。随后基于Hyperledger Fabric平台在不同的数据集进行对比试验，验证本文方法的高效性与可行性。

在基于数据分片的区块链溯源查询优化方法基础上设计基于区块链的供应链溯源方案。分析区块链应用于供应链溯源的可行性，对基于区块链的供应链溯源系统做出设计，将区块链技术与供应链溯源场景相结合，通过方案的数据存储、查询、验证等核心流程实现供应链高效、可信数据溯源，为供应链溯源提供安全的数据存储环境与高效的数据查询方法。

最后以二手车溯源为案例，通过分析基于区块链的二手车溯源流程，结合本文基于数据分片的区块链溯源查询优化方法与基于区块链的供应链溯源方案，在搭建的区块链环境中开发基于区块链的二手车溯源系统。实现二手车数据存储、查询、验证功能，将结果以网页的形式呈现。

Nowadays, commodity quality problems frequently occur in society, and supply chain traceability becomes very important as one of effective supervision means. Traditional supply chain traceability methods have some problems, such as easy data tampering and isolated data island. At present, it is more popular to solve these problems through the characteristics of decentralized storage and node consensus of blockchain technology. However, due to the limited performance of a single node, chain structure and other factors, blockchain has the problems of low query efficiency and single query mode. Aiming at the problems existing in blockchain query, this paper puts forward an optimization method of blockchain traceability query based on data fragmentation, and completes verification and application through Hyperledger Fabric platform. The specific work is as follows:

 Aiming at the problems of low query efficiency and single query mode of blockchain: firstly, combining with the idea of data fragmentation, an optimization method of blockchain traceability query based on data fragmentation is proposed. After the uploaded data reaches a consensus and is broadcast and sent, each node stores the data in the local corresponding fragment according to the information digest, and only the traceability information digest is stored in the chain. When query is needed, the transactions to be queried are distributed to different nodes by chain codes according to transaction summaries for parallel query, thus reducing the number of transactions queried by a single node. According to the transaction scope, the node calls multiple processes to query in parallel locally, which improves the query efficiency. Secondly, according to the diversified demand of supply chain traceability query, four kinds of query requests are abstracted: query the location information of a product at a certain point in time, query all products handled by an individual in a certain period of time, query all raw material information of a product, query all finished product information of a raw material, and give the specific algorithm flow by combining the blockchain traceability query optimization method based on data fragmentation. Then, based on Hyperledger Fabric platform, a comparative experiment was conducted in different data sets to verify the efficiency and feasibility of this method.

Design a supply chain traceability scheme based on blockchain on the basis of blockchain traceability query optimization method based on data fragmentation. This paper analyzes the feasibility of applying blockchain to supply chain traceability, designs a supply chain traceability system based on blockchain, combines blockchain technology with supply chain traceability scenarios, and realizes efficient and verifiable data traceability in supply chain through the core processes of data storage, query and verification of the scheme, thus solving the problems of easy data tampering and poor traceability in traditional supply chain traceability schemes.

Finally, taking the used car traceability as an example, by analyzing the used car traceability process based on blockchain, combining the blockchain traceability query optimization method based on data fragmentation and the supply chain traceability scheme based on blockchain in this paper, the used car traceability system based on blockchain is developed in the built blockchain environment. Realize the storage, query and verification functions of used car data, and present the results in the form of web pages, so as to realize the trusted traceability of used cars.

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