net.sf.farrago.fennel.rel
Class FennelOptionalRel

java.lang.Object
  org.eigenbase.rel.AbstractRelNode
      org.eigenbase.rel.SingleRel
          net.sf.farrago.fennel.rel.FennelSingleRel
              net.sf.farrago.fennel.rel.FennelOptionalRel

All Implemented Interfaces:

Cloneable, FennelRel, RelNode

Direct Known Subclasses:

LcsIndexOnlyScanRel, LcsIndexSearchRel

public abstract class FennelOptionalRel
extends FennelSingleRel

FennelOptionalRel is a FennelRel which either takes zero inputs or takes a single FennelRel as input.

Version:

$Id: //open/dev/farrago/src/net/sf/farrago/fennel/rel/FennelOptionalRel.java#1 $

Author:

John Pham

Field Summary

Fields inherited from class org.eigenbase.rel.AbstractRelNode

digest, id, rowType, traits

Fields inherited from interface net.sf.farrago.query.FennelRel

FENNEL_EXEC_CONVENTION

Fields inherited from interface org.eigenbase.rel.RelNode

emptyArray

Constructor Summary

protected	FennelOptionalRel(RelOptCluster cluster) Creates a new FennelOptionalRel object without an input rel.
protected	FennelOptionalRel(RelOptCluster cluster, RelNode child) Creates a new FennelOptionalRel object with an input rel.

Method Summary

void	childrenAccept(RelVisitor visitor) Interacts with the RelVisitor in a visitor pattern to traverse the tree of relational expressions.
RelNode[]	getInputs() Returns an array of this relational expression's inputs.
double	getRows() Returns an estimate of the number of rows this relational expression will return.
Object	implementFennelChild(FennelRelImplementor implementor) Visits this relational expression as part of the implementation process.

Methods inherited from class net.sf.farrago.fennel.rel.FennelSingleRel

getCollations, getFarragoTypeFactory

Methods inherited from class org.eigenbase.rel.SingleRel

deriveRowType, explain, getChild, replaceInput

Methods inherited from class org.eigenbase.rel.AbstractRelNode

clone, cloneTraits, collectVariablesSet, collectVariablesUsed, computeDigest, computeSelfCost, getChildExps, getCluster, getCollationList, getConvention, getCorrelVariable, getDescription, getDigest, getExpectedInputRowType, getId, getInput, getOrCreateCorrelVariable, getQuery, getRelTypeName, getRowType, getTable, getTraits, getVariablesStopped, inheritTraitsFrom, isAccessTo, isDistinct, isValid, onRegister, recomputeDigest, register, registerCorrelVariable, setCorrelVariable, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface net.sf.farrago.query.FennelRel

toStreamDef

Methods inherited from interface org.eigenbase.rel.RelNode

clone, collectVariablesSet, collectVariablesUsed, computeSelfCost, explain, getChildExps, getCluster, getCollationList, getConvention, getCorrelVariable, getDescription, getDigest, getExpectedInputRowType, getId, getInput, getOrCreateCorrelVariable, getQuery, getRelTypeName, getRowType, getTable, getTraits, getVariablesStopped, isAccessTo, isDistinct, isValid, onRegister, recomputeDigest, registerCorrelVariable, replaceInput, setCorrelVariable

Constructor Detail

FennelOptionalRel

protected FennelOptionalRel(RelOptCluster cluster,
                            RelNode child)

Creates a new FennelOptionalRel object with an input rel.

Parameters:

cluster - RelOptCluster for this rel

child - input rel

FennelOptionalRel

protected FennelOptionalRel(RelOptCluster cluster)

Creates a new FennelOptionalRel object without an input rel.

Parameters:

cluster - RelOptCluster for this rel

Method Detail

getInputs

public RelNode[] getInputs()

Description copied from interface: RelNode

Returns an array of this relational expression's inputs. If there are no inputs, returns an empty array, not null.

Specified by:

getInputs in interface RelNode

Overrides:

getInputs in class SingleRel

childrenAccept

public void childrenAccept(RelVisitor visitor)

Description copied from interface: RelNode

Interacts with the RelVisitor in a visitor pattern to traverse the tree of relational expressions.

Specified by:

childrenAccept in interface RelNode

Overrides:

childrenAccept in class SingleRel

implementFennelChild

public Object implementFennelChild(FennelRelImplementor implementor)

Description copied from interface: FennelRel

Visits this relational expression as part of the implementation process. Fennel relational expressions are implemented in a two-phase process: first call this method, then call FennelRel.toStreamDef(net.sf.farrago.query.FennelRelImplementor).

Specified by:

implementFennelChild in interface FennelRel

Overrides:

implementFennelChild in class FennelSingleRel

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 SingleRel