【摘要】 讲述了索引是什么,以及索引是怎样提高查询性能的。还讨论了在某些环境中索引可能降低性能,并为明智地选择数据表的索引提供了一些指导意见。更多还原

【Abstract】 This thesis narrates what the index is,as well as how the index enhances the inquiry performance.Al- so it discusses that the index possibly reduces the per- formance in certain environment and provides some di- rectives and guidelines on choosing the index of data sheet wisely.更多还原