关键词: 区块链, 智能合约, ETL流程, 查询优化

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