Package se.liu.ida.hefquin.engine.queryproc.impl.poptimizer.cardinality

Class CardinalityEstimationImpl

java.lang.Object

se.liu.ida.hefquin.engine.queryproc.impl.poptimizer.cardinality.CardinalityEstimationImpl

All Implemented Interfaces:

CardinalityEstimation

Direct Known Subclasses:

MinBasedCardinalityEstimationImpl

public class CardinalityEstimationImpl
extends Object
implements CardinalityEstimation

This class implements an approach to cardinality estimation that is based on the following two ideas: First, for leaf nodes in the given plans, which are request operators, the implementation issues cardinality requests to the respective federation members. Second, for joins, the implementation uses the join cardinality estimation approach from the Lusail paper, which is based on variable-specific cardinality estimates. To functionality to obtain the variable-specific cardinality estimates is implemented separately (see VarSpecificCardinalityEstimation.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
protected class	CardinalityEstimationImpl.WorkerForRequestOps
protected class	CardinalityEstimationImpl.WorkerForSubquery

Field Summary

Fields

Modifier and Type	Field	Description
protected final Map<PhysicalPlan,CompletableFuture<Integer>>	cache
protected final FederationAccessManager	fedAccessMgr
protected final VarSpecificCardinalityEstimation	vsCardEstimator

Constructor Summary

Constructors

Constructor	Description
CardinalityEstimationImpl(QueryProcContext ctxt)

Method Summary

Modifier and Type	Method	Description
CompletableFuture<Integer>	_initiateCardinalityEstimation(PhysicalPlan plan)
CompletableFuture<Integer>	initiateCardinalityEstimation(PhysicalPlan plan)	Asynchronous method that initiates a process to estimate the cardinality of the result that will be produced by the given plan.

Methods inherited from class java.lang.Object

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

Field Details

cache

protected final Map<PhysicalPlan,CompletableFuture<Integer>> cache

fedAccessMgr

protected final FederationAccessManager fedAccessMgr

vsCardEstimator

protected final VarSpecificCardinalityEstimation vsCardEstimator

Constructor Details

CardinalityEstimationImpl

public CardinalityEstimationImpl(QueryProcContext ctxt)

Method Details

initiateCardinalityEstimation

public CompletableFuture<Integer> initiateCardinalityEstimation(PhysicalPlan plan)

Description copied from interface: CardinalityEstimation

Asynchronous method that initiates a process to estimate the cardinality of the result that will be produced by the given plan. The actual estimate can then be obtained by using the get() method of the returned CompletableFuture. For some helper methods that wrap calls to this method and provide its functionality as synchronous functions, refer to CardinalityEstimationUtils.

Specified by:

initiateCardinalityEstimation in interface CardinalityEstimation

_initiateCardinalityEstimation

public CompletableFuture<Integer> _initiateCardinalityEstimation(PhysicalPlan plan)