Class FilterOptimizer
java.lang.Object
org.eclipse.rdf4j.query.algebra.evaluation.impl.FilterOptimizer
- All Implemented Interfaces:
QueryOptimizer
Optimizes a query model by pushing
Filter
s 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 Filter
s. 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
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Nested Class Summary
Modifier and TypeClassDescriptionprotected static class
protected static class
protected static class
protected static class
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Constructor Summary
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Method Summary
Modifier and TypeMethodDescriptionvoid
optimize
(TupleExpr tupleExpr, Dataset dataset, BindingSet bindings)
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Constructor Details
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FilterOptimizer
public FilterOptimizer()
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Method Details
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optimize
- Specified by:
optimize
in interfaceQueryOptimizer
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