Abstract: Blockchain applications have the advantages of decentralization, traceability, and non-tampering. However, the existing blockchain system is difficult to meet the query and access requirements of data under large data volume. Aiming at the above problems, combined with the characteristics of ETL process and blockchain, a blockchain application query optimization process model ETLVQ（Extract-Transform-Load-Validation-Query） is proposed. The model is divided into three phases. In the first phase, the data of the heterogeneous data source in the blockchain application are extracted, converted and loaded into the query optimization data warehouse. During the verification phase, the loaded data are checked for consistency, and the query access service is provided externally during the query phase. Under the premise of ensuring the security of blockchain data, this model significantly improves the query access efficiency and concurrency of blockchain applications.

Key words: blockchain, smart contract, ETL process, query optimization

摘要： 区块链应用有去中心化、可追溯、不可篡改等优点，但现有的区块链系统难以满足在大数据量下数据的查询、访问需求。针对以上问题，结合ETL流程与区块链自身特点，提出一种区块链应用查询优化流程模型ETLVQ（Extract-Transform-Load-Validation-Query）。模型分为三个阶段：在第一阶段将区块链应用中异构数据源的数据进行抽取、转换并加载到查询优化数据仓库中；在验证阶段对加载后数据进行一致性校验；在查询阶段对外提供查询访问服务。该模型在保证区块链数据安全性的前提下，显著提升了区块链应用的查询访问效率与并发能力。

关键词: 区块链, 智能合约, ETL流程, 查询优化