org.eigenbase.relopt
Class RelTraitDef

java.lang.Object
  org.eigenbase.relopt.RelTraitDef

Direct Known Subclasses:

CallingConventionTraitDef, VolcanoPlannerTraitTest.AltTraitDef

public abstract class RelTraitDef
extends Object

RelTraitDef represents a class of RelTraits. Implementations of RelTraitDef may be singletons under the following conditions:

1. if the set of all possible associated RelTraits is finite and fixed (e.g. all RelTraits for this RelTraitDef are known at compile time). For example, the CallingConvention trait meets this requirement, because CallingConvention is effectively an enumeration.
2. Either
   • canConvert(RelOptPlanner, RelTrait, RelTrait) and convert(RelOptPlanner, RelNode, RelTrait, boolean) do not require planner-instance-specific information, or
   • the RelTraitDef manages separate sets of conversion data internally. See CallingConventionTraitDef for an example of this.

Otherwise, a new instance of RelTraitDef must be constructed and registered with each new planner instantiated.

Version:

$Id: //open/dev/farrago/src/org/eigenbase/relopt/RelTraitDef.java#12 $

Author:

Stephan Zuercher

Field Summary

private WeakHashMap<RelTrait,WeakReference<RelTrait>>

canonicalMap

Constructor Summary

RelTraitDef()

Method Summary

abstract boolean	canConvert(RelOptPlanner planner, RelTrait fromTrait, RelTrait toTrait) Tests whether the given RelTrait can be converted to another RelTrait.
RelTrait	canonize(RelTrait trait) Takes an arbitrary RelTrait and returns the canonical representation of that RelTrait.
abstract RelNode	convert(RelOptPlanner planner, RelNode rel, RelTrait toTrait, boolean allowInfiniteCostConverters) Converts the given RelNode to the given RelTrait.
void	deregisterConverterRule(RelOptPlanner planner, ConverterRule converterRule) Provides notification that a particular ConverterRule has been deregistered from a RelOptPlanner.
abstract String	getSimpleName()
abstract Class	getTraitClass()
void	registerConverterRule(RelOptPlanner planner, ConverterRule converterRule) Provides notification of the registration of a particular ConverterRule with a RelOptPlanner.

Methods inherited from class java.lang.Object

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

Field Detail

canonicalMap

private final WeakHashMap<RelTrait,WeakReference<RelTrait>> canonicalMap

Constructor Detail

RelTraitDef

public RelTraitDef()

Method Detail

getTraitClass

public abstract Class getTraitClass()

Returns:

the specific RelTrait type associated with this RelTraitDef.

getSimpleName

public abstract String getSimpleName()

Returns:

a simple name for this RelTraitDef (for use in RelNode.explain(RelOptPlanWriter)).

canonize

public final RelTrait canonize(RelTrait trait)

Takes an arbitrary RelTrait and returns the canonical representation of that RelTrait. Canonized RelTrait objects may always be compared using the equality operator (==).

If an equal RelTrait has already been canonized and is still in use, it will be returned. Otherwise, the given RelTrait is made canonical and returned.

Parameters:

trait - a possibly non-canonical RelTrait

Returns:

a canonical RelTrait.

convert

public abstract RelNode convert(RelOptPlanner planner,
                                RelNode rel,
                                RelTrait toTrait,
                                boolean allowInfiniteCostConverters)

Converts the given RelNode to the given RelTrait.

Parameters:

planner - the planner requesting the conversion

rel - RelNode to convert

toTrait - RelTrait to convert to

allowInfiniteCostConverters - flag indicating whether infinite cost converters are allowe

Returns:

a converted RelNode or null if conversion is not possible

canConvert

public abstract boolean canConvert(RelOptPlanner planner,
                                   RelTrait fromTrait,
                                   RelTrait toTrait)

Tests whether the given RelTrait can be converted to another RelTrait.

Parameters:

planner - the planner requesting the conversion test

fromTrait - the RelTrait to convert from

toTrait - the RelTrait to conver to

Returns:

true if fromTrait can be converted to toTrait

registerConverterRule

public void registerConverterRule(RelOptPlanner planner,
                                  ConverterRule converterRule)

Provides notification of the registration of a particular ConverterRule with a RelOptPlanner. The default implementation does nothing.

Parameters:

planner - the planner registering the rule

converterRule - the registered converter rule

deregisterConverterRule

public void deregisterConverterRule(RelOptPlanner planner,
                                    ConverterRule converterRule)

Provides notification that a particular ConverterRule has been deregistered from a RelOptPlanner. The default implementation does nothing.

Parameters:

planner - the planner registering the rule

converterRule - the registered converter rule