Sparql query optimization method
AssigneeHitachi, Ltd.
InventorEiichiro Chishiro
Life of this patent
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Abstract
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.
Claims6
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.
A computer system comprising:
- an input device that receives 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;
- means for 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;
- means for 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 the node of the RDF data and a contracted RDF node with reference to the contraction base table and the contraction table;
- means for 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;
- means for 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;
- means for 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
- means for searching the RDF data by use of the expanded query that has been created and obtaining a search result.
A SPARQL query optimization method for optimizing a SPARQL query by use of a computer, the method comprising:
- searching contracted RDF data obtained by contracting RDF data by use of a contracted query of a query;
- and
- searching the RDF data by use of an expanded query obtained by converting the query with a variable binding table available as a result of the search.
Dependencies are inferred from the claim text.