摘要
本文针对确定型演绎数据库的查询求值问题提出了一种系统的、高效的编译方法。决定DDB效率的两个关键因素是冗余和可能相关事实。为能消除冗余和最小化可能相关事实,我们把编译过程分为两个子阶段。第一子阶段是预编译阶段,它负责可能相关事实的最小化;被称为一般编译阶段的第二子阶段负责冗余的消除。本文对J.D.Ullman提出的规则/目标图进行了合理的扩展,并以此作为统一的形式化体系。对应这两个子阶段,我们分别给出了通用算法的直观的和形式化的描述。
A systematic, efficient compilation for query evaluation of DDBs is proposed. In order to eliminate redundancy and minimize potentially relevant facts-the two key issues concerning to the efficience of a DDB. The compilation phase is further decomposed into pre-compilation which is responsible for the minimization of the potentially relevant facts and general compilation, which is responsible for the elimination of redundancy. The rule/goal graph, devised by J. D. Ullman, is appropriately extended and used as a uniform formalism. Two general algorithms for the two sub-phases respectively are described intuitively and formally.
出处
《计算机工程》
CAS
CSCD
北大核心
1990年第4期8-18,共11页
Computer Engineering
