predicate variable 中文意思是什麼
predicate variable
解釋
關系符號-
The knowledge base system is made up of rule base, predicate base, variable base and dictionary base
模糊知識庫系統由規則庫、謂詞庫、個體變元庫和字典庫組成。 -
When user defined functions ( udfs ) are involved in the join predicate, the algorithms for the computation of relational joins can not be used directly. in the paper, the restricting transformation function r, is defined, which can restrict some variable ' s values. without scanning the entire relation, performance of join algorithm can be improved greatly
當連接條件中包含用戶自定義的復雜函數時，原有的連接演算法不能直接應用於該連接運算，為此，本文提出了限定變換函數t _ r概念，來限定連接謂詞中某些變元的取值范圍，從而避免對整個關系的掃描，達到提高連接演算法性能的目的。
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