Two Layer Cache for RDF Database

With the Semantic Web[1]has been paid more and more attention, there are more and more related applications. For instance, Google has provided semantic retrieval functions, you can get the information of some famous people directly. RDF[2]database as the data storage tool of Semantic Web also gets many attentions. Now, there are some well-known RDF databases such as Jena[3], Sesame[4], Big data[5] and so on. The role of RDF database is to provide data service for Semantic Web applications. The important metric of database is the query efficiency. Now, most of RDF database's efficiency has not reached high level and there is a large gap between it and commercial demand[6][7]. In this paper, we present a two layer cache mechanism: RC (RDF database Cache) to speed up the queries and relieve the problem that the runtime of some queries is too long in RDF database. By implementing and test, the query efficiency can increase thirty-one percent or more after using this cache mechanism.