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

## Class ProjectionRemovalOptimizer

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

- All Implemented Interfaces:
    `QueryOptimizer`

      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`