Abstract:
본 발명의 일실시예에 따른 엑스쿼리 질의 조인 비용 추정기의 조인 연산 비용 추정 방법은, 사용자로부터 작성된 엑스쿼리(XQuery) 질의를 분석하는 단계; 조인(join)되는 각 노드(node)의 선택치(selectivity)를 추정하는 단계; 상기 추정된 상기 각 노드의 선택치를 통해 각 노드 페어(pair)의 조인 비용을 추정하는 단계; 및 상기 추정된 상기 조인 비용을 통해 총 조인 비용을 추정하는 단계를 포함한다. 엑스쿼리 질의, 엑스쿼리 질의 처리기, XML 데이터, 조인 비용 추정, 분산 엑스쿼리 처리, 조인 연산
Abstract:
PURPOSE: A service inference system in ubiquitous sensor network environment is provided to inference a service result by sensing a situation from a sensing value of the sensors. CONSTITUTION: A rule management unit(210) manages regulation. An ontology management unit(220) manages the ontology. A context management unit(230) receives the request of service from the application system. According to the flow of task, the context administration unit controls the execution of service. An ontology based deduction unit(240) reasons the necessary sensor in the service. A rule based deduction unit(250) deducts a reference value according to the deduced sensors. An information collecting unit(260) transfers the sensing value of sensors to the context administration unit.
Abstract:
PURPOSE: A method for estimating a join cost in XQuery through an XQuery join cost estimator is provided to efficiently process a join operation included in the XQuery by estimating a join operation cost through estimated selectivity. CONSTITUTION: An XQuery written by a user is analyzed(201), and selectivity of each node which is joined is estimated(202). Join cost of each node pair is estimated through the selection value of estimated each node(203). The total join cost is estimated through the estimated join cost(204). The XQuery is written for distributed XML(eXtensible Displayup Language) views. The XML view comprises each node occurrence information and cardinality information.