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

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

All Implemented Interfaces:

OptimizerRule

@Immutable
public class AddAccessNodes
extends Object
implements OptimizerRule

An optimizer rule that inserts an ACCESS above each SOURCE leaf node in a query plan. This rule is often the first rule to run against a canonical plan (see RuleBasedOptimizer.populateRuleStack(LinkedList, PlanHints).

Before:

        ...
         |
       SOURCE
 

After:

        ...
         |
       ACCESS
         |
       SOURCE
 

Field Summary

static AddAccessNodes

INSTANCE

Constructor Summary

AddAccessNodes()

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 AddAccessNodes INSTANCE

Constructor Detail

AddAccessNodes

public AddAccessNodes()

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()