%0 Journal Article
%T Optimization of Multiple User-Defined Functions in a Query Using Interval Constraints<br>利用区间约束优化包含多个用户函数的查询
%A YANG Bo
%A HONG Xiao guang
%A WANG Hai yang
%A <br>杨波
%A 洪晓光
%A 王海洋
%J 软件学报
%D 2001
%I 
%X How to process user defined functions incorporated in declarative query languages efficiently is an important aspect of query optimization. The problem of several user-defined functions in a query clause hasn't been solved in the former researches. There isn't a proposal in these researches that can be implemented easily. In this paper, a 3-stage optimization plan is put forward, which has the potency of processing several user-defined functions in a query clause: firstly, rewrite user-defined functions equivalently in the form of interval constraints; secondly, stratify the constraints and eliminats the redundant ones; finally, select the optimal execution strategy. This plan has the virtue of easy implementation and higher efficiency. Especially when the user-defined functions imply join conditions of several tables, this plan can get an obvious optimization result.
%K constraint database
%K query optimization
%K user defined function
%K interval constraints
%K join<br>约束数据库
%K 查询优化
%K 用户定义函数
%K 区间约束
%K 连接
%U http://www.alljournals.cn/get_abstract_url.aspx?pcid=5B3AB970F71A803DEACDC0559115BFCF0A068CD97DD29835&cid=8240383F08CE46C8B05036380D75B607&jid=7735F413D429542E610B3D6AC0D5EC59&aid=6958344948836E07&yid=14E7EF987E4155E6&vid=59906B3B2830C2C5&iid=9CF7A0430CBB2DFD&sid=532CB3FA5DC08D32&eid=C4160F9DDB7598AD&journal_id=1000-9825&journal_name=软件学报&referenced_num=1&reference_num=3