Then briefly described the three major search engines FTP performance indicators, namely precision, recall, query cost.
接着简略阐述了FTP搜索引擎三大性能指标,即查准率、查全率、查询代价。
参考来源 - 基于Linux平台FTP搜索引擎的研究However, lazy learning also has a disadvantage of expensive querying cost, because all distances between query instance and every instance of training instances have to be computed when classifying query instances.
然而由于惰性学习在分类查询实例时,需要计算查询实例与所有存储实例的距离,因而存在查询代价大的缺点。
参考来源 - 惰性学习中实例选择研究与应用·2,447,543篇论文数据，部分数据来源于NoteExpress
同时给出了查询代价视图选择问题的代价模型和实视图选择的过程。
In the meantime, the cost model of the query cost view selection problem and the process of materialized views selection are presented.
有的在向前或向后遍历时产生了大量的冗余数据，从而造成查询代价较大。
Some traverse forward or backward generated a lot of redundant data, resulting in greater price inquiries.
然而，这并非一定是代价最高的查询。
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