嵌入式数据库多连接查询优化算法的研究

针对地质灾害监测数据管理系统分布式体系结构下的复杂多连接查询，系统介绍了粒子群优化算法的原理和特点，并分析了采用粒子群优化算法求解多连接查询优化问题的有效性．该算法以左深树为搜索空间，采用有序串编码，并改进了基本粒子群优化算法的速度位置公式，将其应用于地质灾害监测数据的测试实验中，取得了良好的效果．

Research on Multi-join Query Optimization Algorithms for Embedded Databases

Aiming at the issues of complicated multi-join query in the distributed architecture of disaster data management system, this thesis systemically introduces the principles and characteristics of particle swarm optimization （PSO） algorithm, and analyzes the effectiveness of applying PSO to solve the multi-join query optimization problem. The algorithm takes the left-deep tree as search space and adopts ordered string encoding to improve the basic formulas in PSO algorithm. The experimental results of applying this algorithm to the disaster data are sufficiently up to satisfaction.