gStore is an open-source native Resource Description Framework （RDF） triple store that answers SPARQL queries by subgraph matching over RDF graphs. However, there are some deficiencies in the original system design,...gStore is an open-source native Resource Description Framework （RDF） triple store that answers SPARQL queries by subgraph matching over RDF graphs. However, there are some deficiencies in the original system design, such as answering simple queries （including one-triple pattern queries）. To improve the efficiency of the system, we reconsider the system design in this paper. Specifically, we propose a new query plan generation module that generates different query plans according to the structures of query graphs. Furthermore, we re-design our vertex encoding strategy to achieve more pruning power and a new multi-join algorithm to speed up the subgraph matching process. Extensive experiments on synthetic and real RDF datasets show that our method outperforms the state-of-the-art algorithms significantly.展开更多
Aiming at the problem that only some types of SPARQL （ simple protocal and resource description framework query language） queries can be answered by using the current resource description framework link traversal ba...Aiming at the problem that only some types of SPARQL （ simple protocal and resource description framework query language） queries can be answered by using the current resource description framework link traversal based query execution （RDF-LTE） approach, this paper discusses how the execution order of the triple pattern affects the query results and cost based on concrete SPARQL queries, and analyzes two properties of the web of linked data, missing backward links and missing contingency solution. Then three heuristic principles for logic query plan optimization, namely, the filtered basic graph pattern （FBGP） principle, the triple pattern chain principle and the seed URIs principle, are proposed. The three principles contribute to decrease the intermediate solutions and increase the types of queries that can be answered. The effectiveness and feasibility of the proposed approach is evaluated. The experimental results show that more query results can be returned with less cost, thus enabling users to develop the full potential of the web of linked data.展开更多
采用分布式来实现SPARQL(Simple Protocol and RDF Query Language)查询是解决海量RDF(Resource Description Framework)查询的一种新思路。目前实现的基于Hadoop的RDF查询都要启用多个MapReduce来完成任务,浪费时间。为了克服此缺点,提...采用分布式来实现SPARQL(Simple Protocol and RDF Query Language)查询是解决海量RDF(Resource Description Framework)查询的一种新思路。目前实现的基于Hadoop的RDF查询都要启用多个MapReduce来完成任务,浪费时间。为了克服此缺点,提出MRQJ(using MapReduce to query and join)算法,用以实现SPARQL的分布式查询。该算法分为连接计划生成与SPARQL查询执行两个部分:连接计划生成采用贪心策略,生成最优的连接方案;在SPARQL查询执行中只需结合一次MapReduce计算即可得到查询结果。在LUBM数据集上进行的测试实验表明:在查询语句较为复杂的情况下,MRQJ方法的查询效率具有明显的优势。展开更多
文摘gStore is an open-source native Resource Description Framework （RDF） triple store that answers SPARQL queries by subgraph matching over RDF graphs. However, there are some deficiencies in the original system design, such as answering simple queries （including one-triple pattern queries）. To improve the efficiency of the system, we reconsider the system design in this paper. Specifically, we propose a new query plan generation module that generates different query plans according to the structures of query graphs. Furthermore, we re-design our vertex encoding strategy to achieve more pruning power and a new multi-join algorithm to speed up the subgraph matching process. Extensive experiments on synthetic and real RDF datasets show that our method outperforms the state-of-the-art algorithms significantly.
基金The National Natural Science Foundation of China(No.61070170)the Natural Science Foundation of Higher Education Institutions of Jiangsu Province(No.11KJB520017)Suzhou Application Foundation Research Project(No.SYG201238)
文摘Aiming at the problem that only some types of SPARQL （ simple protocal and resource description framework query language） queries can be answered by using the current resource description framework link traversal based query execution （RDF-LTE） approach, this paper discusses how the execution order of the triple pattern affects the query results and cost based on concrete SPARQL queries, and analyzes two properties of the web of linked data, missing backward links and missing contingency solution. Then three heuristic principles for logic query plan optimization, namely, the filtered basic graph pattern （FBGP） principle, the triple pattern chain principle and the seed URIs principle, are proposed. The three principles contribute to decrease the intermediate solutions and increase the types of queries that can be answered. The effectiveness and feasibility of the proposed approach is evaluated. The experimental results show that more query results can be returned with less cost, thus enabling users to develop the full potential of the web of linked data.
文摘采用分布式来实现SPARQL(Simple Protocol and RDF Query Language)查询是解决海量RDF(Resource Description Framework)查询的一种新思路。目前实现的基于Hadoop的RDF查询都要启用多个MapReduce来完成任务,浪费时间。为了克服此缺点,提出MRQJ(using MapReduce to query and join)算法,用以实现SPARQL的分布式查询。该算法分为连接计划生成与SPARQL查询执行两个部分:连接计划生成采用贪心策略,生成最优的连接方案;在SPARQL查询执行中只需结合一次MapReduce计算即可得到查询结果。在LUBM数据集上进行的测试实验表明:在查询语句较为复杂的情况下,MRQJ方法的查询效率具有明显的优势。
