ORM中基于语义相似性的查询缓存替换策略

A Query Cache Replacement Scheme Based on Semantic Comparability Metric in ORM

针对查询的时间局部性特点,提出基于语义缓存查询SC(semantic comparability)替换策略.该策略通过分析缓存项与查询项在关系、条件及查询属性3个方面的相关性,并结合数据访问频率将相似性最小的缓存项予以淘汰.实验结果表明,基于查询序列的先后关系,有选择性的保留与查询具有继承、关联等关系的缓存项,能够得到更高的查询命中率及更短的查询响应时间.在缓存空间相同的情况下,SC策略优于LRU策略.

The SC （semantic comparability） cache replacement policy for semantic cache was proposed, which took into account the characteristic of query locality. This policy analyses the relativity between query items and caching items in several aspects, such as relation, condition and query attribute, and then collaborate with the data access frequency metric to determine the least similar item in cache. Performance testing results have validated that the SC replacement policy can achieve higher hit ratio and lesser query response time than the LRU policy when the queries are correlated and appear successively.