Research On RDF Graph Query Optimization Method Based On Subgraph Matching

In recent years,the development of semantic technology has made the semantic Web of Things a hot topic.The graph query technology based on the RDF graph has been widely used and applied in different fields,such as social networks,intelligent transportation,and smart cities.Due to the large number of RDF data being released,the structure of RDF graphs are more and more complicated.Therefore,the traditional graph traversal method will produce higher query intermediate result redundancy.More seriously,the circle path and the star path of the composite query graph cause repeated traversal of vertices during the query process.The above two cases reduce the query efficiency and query performance of the RDF graph.In response to the above questions,a large number of theoretical analysis and experimental verification are carried out in this paper by comparing the advantages and disadvantages of the existing RDF graph query optimization method.A query optimization method for RDF graphs with large RDF data and high complexity RDF query graphs is proposed.The main work during the research period of this subject is as follows:first of all,several existing RDF graph query optimization methods are introduced in this paper.According to the comparison of a large number of methods and algorithm validity experiments,the defects of the current query optimization methods based on RDF graphs are pointed out.Then,by analyzing the basic structure of several RDF graphs,based on the predicate structure generality between the RDF data graph and the query graph,an extended-way predicate path index structure suitable for large RDF graphs is established.The graph structure is transformed into the tree structure and the traversal of useless vertices is reduced according to the predicate path.Before the start of the query,the RDF graph segmentation technique based on taxonomy was adopted,and the computational model based on integer linear programming problem was established.The complete RDF graph segmentation rule was proposed.The complex query graph is divided into several simple query subgraphs to simplify the query graph structure,and the query results are matched by the index tree.Finally,the RDF subgraph filtering and connection process based on graph structure segmentation is designed.The obtained subgraphs are connected to obtain the desired query results.