org.apache.derby.iapi.sql.compile

Interface CostEstimate

All Superinterfaces:

StoreCostResult

public interface CostEstimate
extends StoreCostResult

A CostEstimate represents the cost of getting a ResultSet, along with the ordering of rows in the ResultSet, and the estimated number of rows in this ResultSet.

Method Summary

Modifier and Type	Method and Description
CostEstimate	add(CostEstimate addend, CostEstimate retval) Add this cost estimate to another one.
CostEstimate	cloneMe() Get a copy of this CostEstimate
double	compare(CostEstimate other) Compare this cost estimate with the given cost estimate.
CostEstimate	divide(double divisor, CostEstimate retval) Divide this cost estimate by a scalar, non-dimensional number.
boolean	isUninitialized() Return whether or not this CostEstimate is uninitialized.
CostEstimate	multiply(double multiplicand, CostEstimate retval) Multiply this cost estimate by a scalar, non-dimensional number.
double	rowCount() Get the estimated number of rows returned by the ResultSet that this CostEstimate models.
void	setCost(CostEstimate other) Copy the values from the given cost estimate into this one.
void	setCost(double cost, double rowCount, double singleScanRowCount) Set the cost for this cost estimate.
void	setSingleScanRowCount(double singleRowScanCount) Set the single scan row count.
double	singleScanRowCount() Get the estimated number of rows returned by a single scan of the ResultSet that this CostEstimate models.

Methods inherited from interface org.apache.derby.iapi.store.access.StoreCostResult

getEstimatedCost, getEstimatedRowCount, setEstimatedCost, setEstimatedRowCount

Method Detail

setCost

void setCost(double cost,
             double rowCount,
             double singleScanRowCount)

Set the cost for this cost estimate.

setCost

void setCost(CostEstimate other)

Copy the values from the given cost estimate into this one.

setSingleScanRowCount

void setSingleScanRowCount(double singleRowScanCount)

Set the single scan row count.

compare

double compare(CostEstimate other)

Compare this cost estimate with the given cost estimate.

Parameters:

other - The cost estimate to compare this one with

Returns:

< 0 if this < other, 0 if this == other, > 0 if this > other

add

CostEstimate add(CostEstimate addend,
                 CostEstimate retval)

Add this cost estimate to another one. This presumes that any row ordering is destroyed.

Parameters:

addend - This cost estimate to add this one to.

retval - If non-null, put the result here.

Returns:

this + other.

multiply

CostEstimate multiply(double multiplicand,
                      CostEstimate retval)

Multiply this cost estimate by a scalar, non-dimensional number. This presumes that any row ordering is destroyed.

Parameters:

multiplicand - The value to multiply this CostEstimate by.

retval - If non-null, put the result here.

Returns:

this * multiplicand

divide

CostEstimate divide(double divisor,
                    CostEstimate retval)

Divide this cost estimate by a scalar, non-dimensional number.

Parameters:

divisor - The value to divide this CostEstimate by.

retval - If non-null, put the result here.

Returns:

this / divisor

rowCount

double rowCount()

Get the estimated number of rows returned by the ResultSet that this CostEstimate models.

singleScanRowCount

double singleScanRowCount()

Get the estimated number of rows returned by a single scan of the ResultSet that this CostEstimate models.

cloneMe

CostEstimate cloneMe()

Get a copy of this CostEstimate

isUninitialized

boolean isUninitialized()

Return whether or not this CostEstimate is uninitialized.

Returns:

Whether or not this CostEstimate is uninitialized.