【摘要】 对于一个给定的查询,通常会有多种可能的策略,查询优化就是能从这许多策略中找出最有效查询计划的一种处理过程。一个好的查询策略往往比一个坏的查询策略在执行效率 (基于执行时间)上高出几个数量级。本文简要说明了分布式数据库的概念和特点,重点讨论了在分布式数据库下的数据库查询优化策略。更多还原

【Abstract】 There are alw ays many available solutions according to a certain query task. Query optimization aims to find the most efficient solution among many feasible query plans. An optimized query solution can often spend much little cost (based on executing time) than a worse one. The thesis explains the concept and feature of distributed database, it emphatically discusses many feasible optimized query solutions based on distributed database.更多还原