SPARQL QUERY OPTIMIZATION METHOD

摘要

Prior to query execution a compressed table and compressed RDF data are created by use of: RDF data stored in an external storage device; and a compression reference table entered from an input device. The compression reference table is used to create a compressed query from an original query entered from the input device, and the compressed RDF data is searched to generate a variable biding table. An expanded query having a node added thereto is next created by use of the original query and the variable binding table, the node restricting a variable value range. The expanded query and the original RDF data are used to generate a query execution result at last.

主权项

1. A SPARQL query optimization method for optimizing a SPARQL query by use of a computer, the method comprising the steps of:
receiving from an input device a contraction base table in which a basis to associate a plurality of literals in RDF data held by an RDF store with one value referred to as a contracted literal is defined; generating a contraction table to associate a plurality of resources included in the RDF data with one contracted literal with reference to the contraction base table; creating contracted RDF data obtained by integrating a plurality of nodes of the RDF data into one node and adding, to the RDF data, a triple representing a correspondence relation between a node of the RDF data and a contracted RDF node with reference to the contraction base table and the contraction table; receiving a SPARQL query from the input device and creating a contracted query obtained by replacing a literal in the query that has been input by a corresponding contracted literal with reference to the contraction base table; searching the contracted RDF data by use of the contracted query and generating a variable binding table in which a contracted literal possessed by each variable in the query is recorded; creating an expanded query obtained by adding to the query a variable node of restricted range that specifies a contracted literal possessed by each variable with reference to the variable binding table that has been generated; and searching the RDF data by use of the expanded query that has been created and obtaining a search result.