Package org.apache.lucene.search

Class Rescorer

java.lang.Object

org.apache.lucene.search.Rescorer

Direct Known Subclasses:

QueryRescorer, SortRescorer

public abstract class Rescorer
extends Object

Re-scores the topN results (TopDocs) from an original query. See QueryRescorer for an actual implementation. Typically, you run a low-cost first-pass query across the entire index, collecting the top few hundred hits perhaps, and then use this class to mix in a more costly second pass scoring.

See QueryRescorer.rescore(IndexSearcher,TopDocs,Query,double,int) for a simple static method to call to rescore using a 2nd pass Query.

Constructor Summary

Constructors

Constructor	Description
Rescorer()

Method Summary

Modifier and Type	Method	Description
abstract Explanation	explain(IndexSearcher searcher, Explanation firstPassExplanation, int docID)	Explains how the score for the specified document was computed.
abstract TopDocs	rescore(IndexSearcher searcher, TopDocs firstPassTopDocs, int topN)	Rescore an initial first-pass TopDocs.

Methods inherited from class java.lang.Object

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

Constructor Details

Rescorer

public Rescorer()

Method Details

rescore

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

Rescore an initial first-pass TopDocs.

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

Explains how the score for the specified document was computed.

Throws:

IOException