sparql-optimizer

Standalone SPARQL query optimizer

Installation

npm i --save sparql-optimiser

Getting started

Basic optimization

DefaultOptimizer let you perform basic query optimizations on any SPARQL query

'use strict';
 
const DefaultOptimizer = require('sparql-optimizer').DefaultOptimizer;
const optimizer = new DefaultOptimizer();
 
// this query contains a join with an union clause, which should be rewritten into an union of two joins
const query = `
PREFIX rdfs:<http://www.w3.org/2000/01/rdf-schema#>
 
SELECT * WHERE {
  ?airport a <http://dbpedia.org/ontology/Airport>; rdfs:label ?name.
  { ?airport <http://dbpedia.org/property/iata> 'EZE'@en. }
  UNION
  { ?airport <http://dbpedia.org/ontology/iataLocationIdentifier> 'EZE'@en. }
}
`;
 
// optimize SPARQL query and then print it
console.log(optimizer.optimize(query));

The previous query will be optimized and rewritten as follow:

PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
SELECT * WHERE {
  {
    ?airport <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://dbpedia.org/ontology/Airport>.
    ?airport rdfs:label ?name.
    ?airport <http://dbpedia.org/property/iata> "EZE"@en.
  }
  UNION
  {
    ?airport <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://dbpedia.org/ontology/Airport>.
    ?airport rdfs:label ?name.
    ?airport <http://dbpedia.org/ontology/iataLocationIdentifier> "EZE"@en.
  }
}