异构型分布式数据库系统LSZ的查询优化策略

Query Optimization Strategies in Heterogeneous Distributed Database System LSZ

本文针对现有分布式查询算法的不足和系统的环境,提出了LSZ的查询优化策略,包括:基于启发式规则的语义优化程序和多重连接优化程序。

LSZ is a heterogeneous distributed database system based on different LANs, different microcomputers and different DBMSs It provides a uniform interface through a global relational data language GRDL to data in heterogeneous distributed databases This paper presents the query optimization strategies of LSZ which contains semantic query optimization based on heuristic rules and parallel multi-join optimization. The semantic optimizer transforms a query into a semantically equivalent query that is less expensive than the original query, while the multi-join optimizer takes both communication cost and parallelism into account for processing the transformed query.