net.sf.saffron.rel
Class OneRowRel

java.lang.Object
  |
  +--net.sf.saffron.rel.SaffronRel
        |
        +--net.sf.saffron.rel.OneRowRel

Direct Known Subclasses:

IterOneRowRel, JavaOneRowRel

public class OneRowRel

extends SaffronRel

OneRowRel always returns one row, zero columns.

Since:

23 September, 2001

Version:

$Id: //open/saffron/src/net/sf/saffron/rel/OneRowRel.java#5 $

Author:

jhyde

Field Summary

Fields inherited from class net.sf.saffron.rel.SaffronRel

cluster, digest, emptyArray, id, nextId, rowType

Constructor Summary

OneRowRel(VolcanoCluster cluster)
Creates an OneRow.

Method Summary

Object	clone()
PlanCost	computeSelfCost(SaffronPlanner planner) Returns the cost of this plan (not including children).
protected SaffronType	deriveRowType()

Methods inherited from class net.sf.saffron.rel.SaffronRel

childrenAccept, computeDigest, explain, getChildExps, getCluster, getConvention, getCorrelVariable, getId, getInput, getInputs, getOrCreateCorrelVariable, getQualifier, getQuery, getRelTypeName, getRows, getRowType, getTable, getVariablesStopped, implement, implementFieldAccess, isAccessTo, isDistinct, 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

OneRowRel

public OneRowRel(VolcanoCluster cluster)

Creates an OneRow.

Parameters:

cluster - VolcanoCluster this relational expression belongs to

Method Detail

clone

public Object clone()

Specified by:

clone in class SaffronRel

computeSelfCost

public PlanCost computeSelfCost(SaffronPlanner planner)

Description copied from class: SaffronRel

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

Overrides:

computeSelfCost in class SaffronRel

deriveRowType

protected SaffronType deriveRowType()

Specified by:

deriveRowType in class SaffronRel