Semantic Query Optimization in Object-Oriented Database

• Main Authors: Shu, Tzu-Shiung, 許智雄
• Other Authors: Tse-Sheng Chen
• Format: Others
• Language: zh-TW
• Published: 1996
• Online Access: http://ndltd.ncl.edu.tw/handle/19838806378800323626

碩士 === 國立成功大學 === 工程科學系 === 84 === Semantic query optimization(SQO) in relational database systems has been studied extensively and has shown its high practice with less query processing cost.Recently, the object-oriented database(OODB) technique has been widely applied in different disciplines of computer data processing. Some important features in OODB will influence the SQO procedure including ISA relationships between classes of inheritance in schema, path expressions in queries, class traversal query processing policy and method calls in queries. Unfortunately, few relative literature or research reports can be found for solving these topics.In this thesis, an investigation on what sematics in OODB can be used in the SQO procedure is propssed. Some key influenced factors for SQO have been surveyed Meanwhile, this study also develops new transformation heuristics which guide useful semantic transformation. Finally, an efficient algorithm is designed for performing the SQO with high throughput. The used semantic network is constructed on the comcept of Rete matching algorithm. It not only solves the problems brought by ISA relationship and path expression, but also reduce dominantcost of SQO into twice multiple of restriction closure computations. The time complexity is acceptable and is bounded by O(n log n), where n is the larger number of the restriction predicates in semantic rules and original query.