Package org.apache.lucene.search

Class QueryRescorer

java.lang.Object

org.apache.lucene.search.Rescorer

org.apache.lucene.search.QueryRescorer

public abstract class QueryRescorer
extends Rescorer

A Rescorer that uses a provided Query to assign scores to the first-pass hits.

WARNING: This API is experimental and might change in incompatible ways in the next release.

Constructor Summary

Constructors

Constructor	Description
QueryRescorer(Query query)	Sole constructor, passing the 2nd pass query to assign scores to the 1st pass hits.

Method Summary

Modifier and Type	Method	Description
protected abstract float	combine(float firstPassScore, boolean secondPassMatches, float secondPassScore)	Implement this in a subclass to combine the first pass and second pass scores.
Explanation	explain(IndexSearcher searcher, Explanation firstPassExplanation, int docID)	Explains how the score for the specified document was computed.
TopDocs	rescore(IndexSearcher searcher, TopDocs firstPassTopDocs, int topN)	Rescore an initial first-pass TopDocs.
static TopDocs	rescore(IndexSearcher searcher, TopDocs topDocs, Query query, double weight, int topN)	Sugar API, calling {#rescore} using a simple linear combination of firstPassScore + weight * secondPassScore

Methods inherited from class java.lang.Object

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

Constructor Detail

QueryRescorer

public QueryRescorer(Query query)

Sole constructor, passing the 2nd pass query to assign scores to the 1st pass hits.

Method Detail

combine

protected abstract float combine(float firstPassScore,
                                 boolean secondPassMatches,
                                 float secondPassScore)

Implement this in a subclass to combine the first pass and second pass scores. If secondPassMatches is false then the second pass query failed to match a hit from the first pass query, and you should ignore the secondPassScore.

rescore

public TopDocs rescore(IndexSearcher searcher,
                       TopDocs firstPassTopDocs,
                       int topN)
                throws IOException

Description copied from class: Rescorer

Rescore an initial first-pass TopDocs.

Specified by:

rescore in class Rescorer

Parameters:

searcher - IndexSearcher used to produce the first pass topDocs

firstPassTopDocs - Hits from the first pass search. It's very important that these hits were produced by the provided searcher; otherwise the doc IDs will not match!

topN - How many re-scored hits to return

Throws:

IOException

explain

public Explanation explain(IndexSearcher searcher,
                           Explanation firstPassExplanation,
                           int docID)
                    throws IOException

Description copied from class: Rescorer

Explains how the score for the specified document was computed.

Specified by:

explain in class Rescorer

Throws:

IOException

rescore

public static TopDocs rescore(IndexSearcher searcher,
                              TopDocs topDocs,
                              Query query,
                              double weight,
                              int topN)
                       throws IOException

Sugar API, calling {#rescore} using a simple linear combination of firstPassScore + weight * secondPassScore

Throws:

IOException