org.eigenbase.rel
Class OneRowRelBase

java.lang.Object
  org.eigenbase.rel.AbstractRelNode
      org.eigenbase.rel.OneRowRelBase

All Implemented Interfaces:

Cloneable, RelNode

Direct Known Subclasses:

IterOneRowRel, OneRowRel

public abstract class OneRowRelBase
extends AbstractRelNode

OneRowRelBase is an abstract base class for implementations of OneRowRel.

Version:

$Id: //open/dev/farrago/src/org/eigenbase/rel/OneRowRelBase.java#8 $

Author:

John V. Sichi

Field Summary

Fields inherited from class org.eigenbase.rel.AbstractRelNode

digest, id, nextId, rowType, traits

Fields inherited from interface org.eigenbase.rel.RelNode

emptyArray

Constructor Summary

protected

OneRowRelBase(RelOptCluster cluster, RelTraitSet traits) Creates a OneRowRelBase with specific traits.

Method Summary

OneRowRelBase	clone() Clones this RelNode.
RelOptCost	computeSelfCost(RelOptPlanner planner) Returns the cost of this plan (not including children).
static RelDataType	deriveOneRowType(RelDataTypeFactory typeFactory)
protected RelDataType	deriveRowType()

Methods inherited from class org.eigenbase.rel.AbstractRelNode

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

Methods inherited from class java.lang.Object

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

Constructor Detail

OneRowRelBase

protected OneRowRelBase(RelOptCluster cluster,
                        RelTraitSet traits)

Creates a OneRowRelBase with specific traits.

Parameters:

cluster - RelOptCluster this relational expression belongs to

traits - for this rel

Method Detail

clone

public OneRowRelBase 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

deriveRowType

protected RelDataType deriveRowType()

Overrides:

deriveRowType in class AbstractRelNode

deriveOneRowType

public static RelDataType deriveOneRowType(RelDataTypeFactory typeFactory)