Package com.apple.foundationdb.record.query.plan.temp

Class ValueIndexScanMatchCandidate

java.lang.Object

com.apple.foundationdb.record.query.plan.temp.ValueIndexScanMatchCandidate

All Implemented Interfaces:

MatchCandidate

public class ValueIndexScanMatchCandidate
extends Object
implements MatchCandidate

Case class to represent a match candidate that is backed by an index.

Constructor Summary

Constructors

Constructor	Description
ValueIndexScanMatchCandidate(String name, ExpressionRefTraversal traversal, List<CorrelationIdentifier> parameters, KeyExpression alternativeKeyExpression)

Method Summary

Modifier and Type	Method	Description
KeyExpression	getAlternativeKeyExpression()	This method returns a key expression that can be used to actually compute the the keys of this candidate for a given record.
String	getName()	Returns the name of the match candidate.
List<CorrelationIdentifier>	getParameters()	Returns the parameter names for all necessary parameters that need to be bound during matching.
ExpressionRefTraversal	getTraversal()	Returns the traversal object for this candidate.
RelationalExpression	toScanExpression(List<ComparisonRange> comparisonRanges, boolean isReverse)	Creates a logical expression that represents a scan over the materialized candidate data.

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.apple.foundationdb.record.query.plan.temp.MatchCandidate

computeBoundParameterPrefixMap, findReferencingExpressions, toScanExpression

Constructor Detail

ValueIndexScanMatchCandidate

public ValueIndexScanMatchCandidate(@Nonnull
                                    String name,
                                    @Nonnull
                                    ExpressionRefTraversal traversal,
                                    @Nonnull
                                    List<CorrelationIdentifier> parameters,
                                    @Nonnull
                                    KeyExpression alternativeKeyExpression)

Method Detail

getName

@Nonnull
public String getName()

Description copied from interface: MatchCandidate

Returns the name of the match candidate. If this candidate represents and index, it will be the name of the index.

Specified by:

getName in interface MatchCandidate

Returns:

the name of this match candidate

getTraversal

@Nonnull
public ExpressionRefTraversal getTraversal()

Description copied from interface: MatchCandidate

Returns the traversal object for this candidate. The traversal object can either be computed up-front when the candidate is created or lazily when this method is invoked. It is, however, necessary that the traversal once computed is stable, meaning the object returned by implementors of this method must always return the same object.

Specified by:

getTraversal in interface MatchCandidate

Returns:

the traversal associated for this match candidate

getParameters

@Nonnull
public List<CorrelationIdentifier> getParameters()

Description copied from interface: MatchCandidate

Returns the parameter names for all necessary parameters that need to be bound during matching.

Specified by:

getParameters in interface MatchCandidate

Returns:

a list of CorrelationIdentifiers for all the used parameters in this match candidate

getAlternativeKeyExpression

@Nonnull
public KeyExpression getAlternativeKeyExpression()

Description copied from interface: MatchCandidate

This method returns a key expression that can be used to actually compute the the keys of this candidate for a given record. The current expression hierarchy cannot be evaluated at runtime (in general). This key expression helps representing compensation or part of compensation if needed.

Specified by:

getAlternativeKeyExpression in interface MatchCandidate

Returns:

a key expression that can be evaluated based on a base record

toScanExpression

@Nonnull
public RelationalExpression toScanExpression(@Nonnull
                                             List<ComparisonRange> comparisonRanges,
                                             boolean isReverse)

Description copied from interface: MatchCandidate

Creates a logical expression that represents a scan over the materialized candidate data. This method is expected to be implemented by specific implementations of MatchCandidate.

Specified by:

toScanExpression in interface MatchCandidate

Parameters:

comparisonRanges - a List of ComparisonRanges to be applied

isReverse - an indicator whether this expression should conceptually flow data in an ascending (forward) or descending (backward or reverse) order

Returns:

a new RelationalExpression