simpledb

Class PlanCache

java.lang.Object

simpledb.PlanCache

public class PlanCache
extends java.lang.Object

A PlanCache is a helper class that can be used to store the best way to order a given set of joins

Field Summary

Fields

Modifier and Type	Field and Description
(package private) java.util.HashMap<java.util.Set<LogicalJoinNode>,java.lang.Integer>	bestCardinalities
(package private) java.util.HashMap<java.util.Set<LogicalJoinNode>,java.lang.Double>	bestCosts
(package private) java.util.HashMap<java.util.Set<LogicalJoinNode>,java.util.Vector<LogicalJoinNode>>	bestOrders

Constructor Summary

Constructors

Constructor and Description
PlanCache()

Method Summary

Modifier and Type	Method and Description
(package private) void	addPlan(java.util.Set<LogicalJoinNode> s, double cost, int card, java.util.Vector<LogicalJoinNode> order) Add a new cost, cardinality and ordering for a particular join set.
(package private) int	getCard(java.util.Set<LogicalJoinNode> s) Find the cardinality of the best join order in the cache for the specified plan
(package private) double	getCost(java.util.Set<LogicalJoinNode> s) Find the cost of the best join order in the cache for the specified plan
(package private) java.util.Vector<LogicalJoinNode>	getOrder(java.util.Set<LogicalJoinNode> s) Find the best join order in the cache for the specified plan

Methods inherited from class java.lang.Object

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

Field Detail

bestOrders

java.util.HashMap<java.util.Set<LogicalJoinNode>,java.util.Vector<LogicalJoinNode>> bestOrders

bestCosts

java.util.HashMap<java.util.Set<LogicalJoinNode>,java.lang.Double> bestCosts

bestCardinalities

java.util.HashMap<java.util.Set<LogicalJoinNode>,java.lang.Integer> bestCardinalities

Constructor Detail

PlanCache

public PlanCache()

Method Detail

addPlan

void addPlan(java.util.Set<LogicalJoinNode> s,
             double cost,
             int card,
             java.util.Vector<LogicalJoinNode> order)

Add a new cost, cardinality and ordering for a particular join set. Does not verify that the new cost is less than any previously added cost -- simply adds or replaces an existing plan for the specified join set

Parameters:

s - the set of joins for which a new ordering (plan) is being added

cost - the estimated cost of the specified plan

card - the estimatied cardinality of the specified plan

order - the ordering of the joins in the plan

getOrder

java.util.Vector<LogicalJoinNode> getOrder(java.util.Set<LogicalJoinNode> s)

Find the best join order in the cache for the specified plan

Parameters:

s - the set of joins to look up the best order for

Returns:

the best order for s in the cache

getCost

double getCost(java.util.Set<LogicalJoinNode> s)

Find the cost of the best join order in the cache for the specified plan

Parameters:

s - the set of joins to look up the best cost for

Returns:

the cost of the best order for s in the cache

getCard

int getCard(java.util.Set<LogicalJoinNode> s)

Find the cardinality of the best join order in the cache for the specified plan

Parameters:

s - the set of joins to look up the best cardinality for

Returns:

the cardinality of the best order for s in the cache