ProjectionRemovalOptimizer (Eclipse RDF4J 4.3.2)

java.lang.Object
- org.eclipse.rdf4j.query.algebra.evaluation.optimizer.ProjectionRemovalOptimizer

All Implemented Interfaces:

QueryOptimizer

Direct Known Subclasses:

ProjectionRemovalOptimizer
```
public class ProjectionRemovalOptimizer
extends Object
implements QueryOptimizer
```
If a projection node in the algebra does not contribute or change the results it can be removed from the tree.
For example SELECT ?s ?p ?o WHERE {?s ?p ?o } Does not need a projection as the inner statement pattern returns the same result.
While * SELECT ?s ?p WHERE {?s ?p ?o } Does as the statement pattern has one more variable in use than the projection.
Note: this optimiser should run after optimisations ran that depend on Projections. e.g.

Author:

Jerven Bolleman

See Also:

UnionScopeChangeOptimizer

- Constructor Summary
  
  Constructors
  Constructor Description
  
  ProjectionRemovalOptimizer()
- Method Summary
  
  All Methods Instance Methods Concrete Methods
  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 Detail
- ProjectionRemovalOptimizer
```
public ProjectionRemovalOptimizer()
```

Method Detail

optimize

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

Specified by:: optimize in interface QueryOptimizer