Abstract: As the amount of stored data grows, blockchain faces the challenge of efficient query under large-scale data. Users hope to understand the trend of blockchain changes through complex queries. But the query cost of the existing blockchain system is high and the results cannot be reused. For this reason, a grouped skip list and a blockchain query system based on it are proposed. The system is incrementally built on the existing blockchain system to provide users with equality query, range query and top-k query solutions. Firstly, a grouped skip list (Gskiplist) data structure is proposed, which aggregates traditional skip list nodes to reduce the number of nodes, thereby improving query efficiency. Users can construct grouped skip list indexes for different fields of blockchain data, and dynamically adjust the index node height according to the conditional probability algorithm and heat value. The index node is persisted in the storage engine at the bottom of the blockchain to retain the decentralized and tamper-proof characteristics of blockchain data. Secondly, a query system is introduced, and index and query modules are added to the query system for users to query efficiently. Finally, a comparative experiment is conducted with mainstream solutions. The experiment uses space cost, insertion efficiency and query efficiency as metrics and uses real block data sets. Experimental results show that the system supports complex queries with good performance on the blockchain at a small space cost, demonstrating the feasibility and superior performance of the proposed system.

Key words: blockchain, grouped skip list, index, equality query, range query, top-k query