org.eigenbase.relopt.hep
Class HepRelVertex

java.lang.Object
  org.eigenbase.rel.AbstractRelNode
      org.eigenbase.relopt.hep.HepRelVertex

All Implemented Interfaces:

Cloneable, RelNode

public class HepRelVertex
extends AbstractRelNode

HepRelVertex wraps a real RelNode as a vertex in a DAG representing the entire query expression.

Version:

$Id: //open/dev/farrago/src/org/eigenbase/relopt/hep/HepRelVertex.java#8 $

Author:

John V. Sichi

Field Summary

private RelNode

currentRel Wrapped rel currently chosen for implementation of expression.

Fields inherited from class org.eigenbase.rel.AbstractRelNode

digest, id, rowType, traits

Fields inherited from interface org.eigenbase.rel.RelNode

emptyArray

Constructor Summary

HepRelVertex(RelNode rel)

Method Summary

HepRelVertex	clone() Clones this RelNode.
protected String	computeDigest() Computes the digest.
RelOptCost	computeSelfCost(RelOptPlanner planner) Returns the cost of this plan (not including children).
protected RelDataType	deriveRowType()
RelNode	getCurrentRel()
double	getRows() Returns an estimate of the number of rows this relational expression will return.
boolean	isDistinct() Returns whether the same value will not come out twice.
(package private) void	replaceRel(RelNode newRel) Replaces the implementation for this expression with a new one.

Methods inherited from class org.eigenbase.rel.AbstractRelNode

childrenAccept, cloneTraits, collectVariablesSet, collectVariablesUsed, explain, getChildExps, getCluster, getCollationList, getConvention, getCorrelVariable, getDescription, getDigest, getExpectedInputRowType, getId, getInput, getInputs, getOrCreateCorrelVariable, getQuery, getRelTypeName, getRowType, getTable, getTraits, getVariablesStopped, inheritTraitsFrom, isAccessTo, isValid, onRegister, recomputeDigest, register, registerCorrelVariable, replaceInput, setCorrelVariable, toString

Methods inherited from class java.lang.Object

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

Field Detail

currentRel

private RelNode currentRel

Wrapped rel currently chosen for implementation of expression.

Constructor Detail

HepRelVertex

HepRelVertex(RelNode rel)

Method Detail

clone

public HepRelVertex clone()

Description copied from interface: RelNode

Clones this RelNode.

Traits of the RelNode must be explicitly cloned, using AbstractRelNode.inheritTraitsFrom(AbstractRelNode), as the RelNode may have traits of which it has no knowledge. Example implementation:

     public MyRelNode clone()
     {
         MyRelNode clone = new MyRelNode(...);
         clone.inheritTraitsFrom(this);
         return clone;
     }
 

N.B.: This method must be overridden whenever an existing, concrete RelNode is extended. Otherwise, calling clone() will produce a differently typed RelNode, resulting in invalid or incorrect query plans.

Specified by:

clone in interface RelNode

Specified by:

clone in class AbstractRelNode

Returns:

a clone of this RelNode

computeSelfCost

public RelOptCost computeSelfCost(RelOptPlanner planner)

Description copied from interface: RelNode

Returns the cost of this plan (not including children). The base implementation throws an error; derived classes should override.

NOTE jvs 29-Mar-2006: Don't call this method directly. Instead, use RelMetadataQuery.getNonCumulativeCost(org.eigenbase.rel.RelNode), which gives plugins a chance to override the rel's default ideas about cost.

Specified by:

computeSelfCost in interface RelNode

Overrides:

computeSelfCost in class AbstractRelNode

getRows

public double getRows()

Description copied from interface: RelNode

Returns an estimate of the number of rows this relational expression will return.

NOTE jvs 29-Mar-2006: Don't call this method directly. Instead, use RelMetadataQuery.getRowCount(org.eigenbase.rel.RelNode), which gives plugins a chance to override the rel's default ideas about row count.

Specified by:

getRows in interface RelNode

Overrides:

getRows in class AbstractRelNode

deriveRowType

protected RelDataType deriveRowType()

Overrides:

deriveRowType in class AbstractRelNode

isDistinct

public boolean isDistinct()

Description copied from interface: RelNode

Returns whether the same value will not come out twice. Default value is false, derived classes should override.

Specified by:

isDistinct in interface RelNode

Overrides:

isDistinct in class AbstractRelNode

computeDigest

protected String computeDigest()

Description copied from class: AbstractRelNode

Computes the digest. Does not modify this object.

Overrides:

computeDigest in class AbstractRelNode

replaceRel

void replaceRel(RelNode newRel)

Replaces the implementation for this expression with a new one.

Parameters:

newRel - new expression

getCurrentRel

public RelNode getCurrentRel()

Returns:

current implementation chosen for this vertex