org.jboss.dna.graph.query.optimize
Class ReplaceViews

java.lang.Object
  org.jboss.dna.graph.query.optimize.ReplaceViews

All Implemented Interfaces:

OptimizerRule

@Immutable
public class ReplaceViews
extends Object
implements OptimizerRule

An optimizer rule that replaces any SOURCE nodes that happen to be views. This rewriting changes all of the elements of the plan that reference the SOURCE and it's columns, including criteria, project nodes, etc.

For example, here is the portion of a plan that uses a single SOURCE that is defined to use a view.

          ...
           |
        SOURCE1
 

This same SOURCE node is then replaced with the view's definition:

          ...
           |
        PROJECT      with the list of columns being SELECTed
           |
        SELECT1
           |         One or more SELECT plan nodes that each have
        SELECT2      a single non-join constraint that are then all AND-ed
           |         together
        SELECTn
           |
        SOURCE
 

Field Summary

static ReplaceViews

INSTANCE

Constructor Summary

ReplaceViews()

Method Summary

PlanNode	execute(QueryContext context, PlanNode plan, LinkedList<OptimizerRule> ruleStack) Optimize the supplied plan using the supplied context, hints, and yet-to-be-run rules.
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

INSTANCE

public static final ReplaceViews INSTANCE

Constructor Detail

ReplaceViews

public ReplaceViews()

Method Detail

execute

public PlanNode execute(QueryContext context,
                        PlanNode plan,
                        LinkedList<OptimizerRule> ruleStack)

Optimize the supplied plan using the supplied context, hints, and yet-to-be-run rules.

Specified by:

execute in interface OptimizerRule

Parameters:

context - the context in which the query is being optimized; never null

plan - the plan to be optimized; never null

ruleStack - the stack of rules that will be run after this rule; never null

Returns:

the optimized plan; never null

See Also:

OptimizerRule.execute(org.jboss.dna.graph.query.QueryContext, org.jboss.dna.graph.query.plan.PlanNode, java.util.LinkedList)

toString

public String toString()

Overrides:

toString in class Object

See Also:

Object.toString()