saffron.rel
Class OneRow

java.lang.Object
  |
  +--saffron.rel.Rel
        |
        +--saffron.rel.OneRow

Direct Known Subclasses:

JavaOneRow

public class OneRow

extends Rel

OneRow always returns one row, zero columns.

Since:

23 September, 2001

Version:

$Id: //open/saffron/src/main/saffron/rel/OneRow.java#7 $

Author:

jhyde

Nested Class Summary

private static class

OneRow.OneRowToJavaRule Converts a OneRow to Java calling convention.

Nested classes inherited from class saffron.rel.Rel

Field Summary

Fields inherited from class saffron.rel.Rel

cluster, digest, emptyArray, id, nextId, rowType

Constructor Summary

OneRow(Cluster cluster)
Creates an OneRow.

Method Summary

Object	clone()
Cost	computeSelfCost(Planner planner) Returns the cost of this plan (not including children).
protected Type	deriveRowType()
static void	register(Planner planner) See Rel.register(saffron.Planner).

Methods inherited from class saffron.rel.Rel

childrenAccept, computeDigest, explain, getChildExps, getCluster, getConvention, getCorelVariable, getEnvironment, getId, getInput, getInputs, getOrCreateCorelVariable, getParentEnv, getQualifier, getQuery, getRelTypeName, getRows, getRowType, getTable, getType, getVariablesStopped, implement, implementExp, implementExps, implementFieldAccess, implementSelf, isAccessTo, isDistinct, onRegister, recomputeDigest, registerCorelVariable, replaceInput, setCorelVariable, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

OneRow

public OneRow(Cluster cluster)

Creates an OneRow.

Parameters:

cluster - Cluster this relational expression belongs to

Method Detail

clone

public Object clone()

Specified by:

clone in class Rel

deriveRowType

protected Type deriveRowType()

Specified by:

deriveRowType in class Rel

computeSelfCost

public Cost computeSelfCost(Planner planner)

Description copied from class: Rel

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

Overrides:

computeSelfCost in class Rel

register

public static void register(Planner planner)

See Rel.register(saffron.Planner).