com.metamatrix.query.optimizer.relational.rules
Class RulePlanJoins

java.lang.Object
  com.metamatrix.query.optimizer.relational.rules.RulePlanJoins

All Implemented Interfaces:

OptimizerRule

public class RulePlanJoins
extends java.lang.Object
implements OptimizerRule

Determines join orderings based upon dependency and cost information The algorithm works as follows: Stage 1. Find join regions. A join region is an set of inner and cross joins (with the join and intermediate criteria removed). Dependency Phase Stage 2. Determine if dependencies found can be satisfied. a. Throw an exception if a quick check fails. Stage 3. A satisfying set of access patterns and join ordering will be found for each join region. a. If this is not possible, an exception will be thrown b. only one possible set of access patterns will be considered Optimization Phase Stage 4. Heuristically push joins down. Join regions (with more than one join source) will be exhaustively searched (bottom up) for join pairs that can be pushed to a source. a. A join is eligible for pushing if the access node can be raised and there is at least one join criteria that can also be pushed. -- costing information is not considered at this point. b. Once a pair has been pushed, they will be replaced in the join region with a single access node. Stage 5. The remaining join regions will be ordered in a left linear tree based upon a an exhaustive, or random, algorithm that considers costing and criteria information.

Field Summary

static int

EXHAUSTIVE_SEARCH_GROUPS

Constructor Summary

RulePlanJoins()

Method Summary

PlanNode	execute(PlanNode plan, QueryMetadataInterface metadata, CapabilitiesFinder capabilitiesFinder, RuleStack rules, AnalysisRecord analysisRecord, CommandContext context)
java.lang.String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

EXHAUSTIVE_SEARCH_GROUPS

public static final int EXHAUSTIVE_SEARCH_GROUPS

See Also:

Constant Field Values

Constructor Detail

RulePlanJoins

public RulePlanJoins()

Method Detail

execute

public PlanNode execute(PlanNode plan,
                        QueryMetadataInterface metadata,
                        CapabilitiesFinder capabilitiesFinder,
                        RuleStack rules,
                        AnalysisRecord analysisRecord,
                        CommandContext context)
                 throws QueryPlannerException,
                        QueryMetadataException,
                        MetaMatrixComponentException

Specified by:

execute in interface OptimizerRule

Throws:

QueryPlannerException

QueryMetadataException

MetaMatrixComponentException

See Also:

OptimizerRule.execute(com.metamatrix.query.optimizer.relational.plantree.PlanNode, com.metamatrix.query.metadata.QueryMetadataInterface, com.metamatrix.query.optimizer.capabilities.CapabilitiesFinder, com.metamatrix.query.optimizer.relational.RuleStack, com.metamatrix.query.analysis.AnalysisRecord, com.metamatrix.query.util.CommandContext)

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

See Also:

Object.toString()