Package org.eclipse.rdf4j.query.algebra.evaluation.impl

Class FilterOptimizer

java.lang.Object

org.eclipse.rdf4j.query.algebra.evaluation.impl.FilterOptimizer

All Implemented Interfaces:

QueryOptimizer

public class FilterOptimizer
extends Object
implements QueryOptimizer

Optimizes a query model by pushing Filters as far down in the model tree as possible. To make the first optimization succeed more often it splits filters which contains And conditions. SELECT * WHERE { ?s ?p ?o . ?s ?p ?o2 . FILTER(?o > '2'^^xsd:int && ?o2 < '4'^^xsd:int) } May be more efficient when decomposed into SELECT * WHERE { ?s ?p ?o . FILTER(?o > '2'^^xsd:int) ?s ?p ?o2 . FILTER(?o2 < '4'^^xsd:int) } Then it optimizes a query model by merging adjacent Filters. e.g. SELECT * WHERE { ?s ?p ?o . FILTER(?o > 2) . FILTER(?o < 4) . } may be merged into SELECT * WHERE { ?s ?p ?o . FILTER(?o > 2 && ?o < 4) . } This optimization allows for sharing evaluation costs in the future and removes an iterator. This is done as a second step to not break the first optimization. In the case that the splitting was done but did not help it is now undone.

Author:

Arjohn Kampman, Jerven Bolleman

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
protected static class	FilterOptimizer.DeMergeFilterFinder
protected static class	FilterOptimizer.FilterFinder
protected static class	FilterOptimizer.FilterRelocator
protected static class	FilterOptimizer.MergeFilterFinder

Constructor Summary

Constructors

Constructor	Description
FilterOptimizer()

Method Summary

Modifier and Type	Method	Description
void	optimize(TupleExpr tupleExpr, Dataset dataset, BindingSet bindings)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

FilterOptimizer

public FilterOptimizer()

Method Details

optimize

public void optimize(TupleExpr tupleExpr,
 Dataset dataset,
 BindingSet bindings)

Specified by:

optimize in interface QueryOptimizer