Module org.apache.jena.arq

Package org.apache.jena.sparql.algebra.optimize

Class TransformFilterPlacementConservative

java.lang.Object

org.apache.jena.sparql.algebra.TransformCopy

org.apache.jena.sparql.algebra.optimize.TransformFilterPlacementConservative

All Implemented Interfaces:

Transform

public class TransformFilterPlacementConservative
extends TransformCopy

Rewrite an algebra expression to put filters as close to their bound variables in a BGP. Works on (filter (BGP ...) )

This is a conservative and relatively limited optimization and has been superseded in the default optimizer by the TransformFilterPlacement as of the 2.11.x releases. This original version of TransformFilterPlacement only operates on filters over BGPs, quad blocks, sequences and conditions (a form of LeftJoin with no scope issues) of the same. However in some cases it may be desirable to have the more limited and conservative behaviour so this is preserved in the code for those who want to use this.

The context flag ARQ.optFilterPlacementConservative may be set to have the default optimizer use this in place of the newer and more aggressive TransformFilterPlacement

Field Summary

Fields inherited from class org.apache.jena.sparql.algebra.TransformCopy

COPY_ALWAYS, COPY_ONLY_ON_CHANGE

Constructor Summary

Constructors

Constructor	Description
TransformFilterPlacementConservative()

Method Summary

Modifier and Type	Method	Description
Op	transform(OpFilter opFilter, Op x)

Methods inherited from class org.apache.jena.sparql.algebra.TransformCopy

transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform

Methods inherited from class java.lang.Object

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

Constructor Details

TransformFilterPlacementConservative

public TransformFilterPlacementConservative()

Method Details

transform

public Op transform(OpFilter opFilter,
 Op x)

Specified by:

transform in interface Transform

Overrides:

transform in class TransformCopy