Package org.apache.lucene.search

Class DisjunctionScoreBlockBoundaryPropagator

java.lang.Object

org.apache.lucene.search.DisjunctionScoreBlockBoundaryPropagator

final class DisjunctionScoreBlockBoundaryPropagator
extends Object

A helper to propagate block boundaries for disjunctions. Because a disjunction matches if any of its sub clauses matches, it is tempting to return the minimum block boundary across all clauses. The problem is that it might then make the query slow when the minimum competitive score is high and low-scoring clauses don't drive iteration anymore. So this class computes block boundaries only across clauses whose maximum score is greater than or equal to the minimum competitive score, or the maximum scoring clause if there is no such clause.

Field Summary

Fields

Modifier and Type	Field	Description
private int	leadIndex
private static final Comparator<Scorer>	MAX_SCORE_COMPARATOR
private final float[]	maxScores
private final Scorer[]	scorers

Constructor Summary

Constructors

Constructor	Description
DisjunctionScoreBlockBoundaryPropagator(Collection<Scorer> scorers)

Method Summary

Modifier and Type	Method	Description
(package private) int	advanceShallow(int target)	See Scorer.advanceShallow(int).
(package private) void	setMinCompetitiveScore(float minScore)	Set the minimum competitive score to filter out clauses that score less than this threshold.

Methods inherited from class java.lang.Object

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

Field Details

MAX_SCORE_COMPARATOR

private static final Comparator<Scorer> MAX_SCORE_COMPARATOR

scorers

private final Scorer[] scorers

maxScores

private final float[] maxScores

leadIndex

private int leadIndex

Constructor Details

DisjunctionScoreBlockBoundaryPropagator

DisjunctionScoreBlockBoundaryPropagator(Collection<Scorer> scorers)
                                 throws IOException

Throws:

IOException

Method Details

advanceShallow

int advanceShallow(int target)
            throws IOException

See Scorer.advanceShallow(int).

Throws:

IOException

setMinCompetitiveScore

void setMinCompetitiveScore(float minScore)
                     throws IOException

Set the minimum competitive score to filter out clauses that score less than this threshold.

Throws:

IOException

See Also:

• Scorable.setMinCompetitiveScore(float)