H2 Database Engine 2.3.232 · org.h2.command.query.Optimizer

Field Summary

Modifier and Type	Field and Description
private final AllColumnsForPlan	allColumnsSet
private Plan	bestPlan
private final Expression	condition
private double	cost
private final TableFilter[]	filters
private static final int	MAX_BRUTE_FORCE
private static final int	MAX_BRUTE_FORCE_FILTERS
private static final int	MAX_GENETIC
private Random	random
private final SessionLocal	session
private long	startNs
private BitSet	switched
private TableFilter	topFilter

Constructor Summary

Access	Constructor and Description
pack-priv	Optimizer(TableFilter[] filters, Expression condition, SessionLocal session)

Method Summary

Modifier and Type	Method and Description
private void	calculateBestPlan()
private void	calculateBruteForceAll()
private void	calculateBruteForceSome()
private void	calculateFakePlan()
private void	calculateGenetic()
private boolean	canStop(int x)
pack-priv double	getCost()
private static int	Returns: the number of filters to calculate using brute force getMaxBruteForceFilters(int the number of filters total filterCount) How many filter to calculate using brute force.
public TableFilter	getTopFilter()
pack-priv void	optimize(boolean If we do not need to really get the best plan because it is a view parsing stage. parse) Calculate the best query plan to use.
private void	shuffleAll(TableFilter[] f)
private boolean	shuffleTwo(TableFilter[] f)
private boolean	testPlan(TableFilter[] list)

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

Field Detail

allColumnsSet	back to summary
private final AllColumnsForPlan allColumnsSet

bestPlan	back to summary
private Plan bestPlan

condition	back to summary
private final Expression condition

cost	back to summary
private double cost

filters	back to summary
private final TableFilter[] filters

MAX_BRUTE_FORCE	back to summary
private static final int MAX_BRUTE_FORCE

MAX_BRUTE_FORCE_FILTERS	back to summary
private static final int MAX_BRUTE_FORCE_FILTERS

MAX_GENETIC	back to summary
private static final int MAX_GENETIC

random	back to summary
private Random random

session	back to summary
private final SessionLocal session

startNs	back to summary
private long startNs

switched	back to summary
private BitSet switched

topFilter	back to summary
private TableFilter topFilter

Constructor Detail

Optimizer	back to summary
pack-priv Optimizer(TableFilter[] filters, Expression condition, SessionLocal session)

Method Detail

calculateBestPlan	back to summary
private void calculateBestPlan()

calculateBruteForceAll	back to summary
private void calculateBruteForceAll()

calculateBruteForceSome	back to summary
private void calculateBruteForceSome()

calculateFakePlan	back to summary
private void calculateFakePlan()

calculateGenetic	back to summary
private void calculateGenetic()

canStop	back to summary
private boolean canStop(int x)

getCost	back to summary
pack-priv double getCost()

getMaxBruteForceFilters	back to summary
private static int getMaxBruteForceFilters(int filterCount) How many filter to calculate using brute force. The remaining filters are selected using a greedy algorithm which has a runtime of (1 + 2 + ... + n) = (n * (n-1) / 2) for n filters. The brute force algorithm has a runtime of n * (n-1) * ... * (n-m) when calculating m brute force of n total. The combined runtime is (brute force) * (greedy). Parameters filterCount:int the number of filters total Returns:int the number of filters to calculate using brute force

getMaxBruteForceFilters

back to summary

private static int getMaxBruteForceFilters(int filterCount)

How many filter to calculate using brute force. The remaining filters are selected using a greedy algorithm which has a runtime of (1 + 2 + ... + n) = (n * (n-1) / 2) for n filters. The brute force algorithm has a runtime of n * (n-1) * ... * (n-m) when calculating m brute force of n total. The combined runtime is (brute force) * (greedy).

Parameters

filterCount:int: the number of filters total

Returns:int

the number of filters to calculate using brute force

getTopFilter	back to summary
public TableFilter getTopFilter()

optimize	back to summary
pack-priv void optimize(boolean parse) Calculate the best query plan to use. Parameters parse:boolean If we do not need to really get the best plan because it is a view parsing stage.

optimize