org.apache.lucene.search

Class BoostingQuery

java.lang.Object

org.apache.lucene.search.Query

org.apache.lucene.search.BoostingQuery

All Implemented Interfaces:

Serializable, Cloneable

public class BoostingQuery
extends Query

The BoostingQuery class can be used to effectively demote results that match a given query. Unlike the "NOT" clause, this still selects documents that contain undesirable terms, but reduces their overall score: Query balancedQuery = new BoostingQuery(positiveQuery, negativeQuery, 0.01f); In this scenario the positiveQuery contains the mandatory, desirable criteria which is used to select all matching documents, and the negativeQuery contains the undesirable elements which are simply used to lessen the scores. Documents that match the negativeQuery have their score multiplied by the supplied "boost" parameter, so this should be less than 1 to achieve a demoting effect This code was originally made available here: [WWW] http://marc.theaimsgroup.com/?l=lucene-user&m=108058407130459&w=2 and is documented here: http://wiki.apache.org/lucene-java/CommunityContributions

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
BoostingQuery(Query match, Query context, float boost)

Method Summary

Methods

Modifier and Type	Method and Description
Query	rewrite(IndexReader reader)
String	toString(String field)

Methods inherited from class org.apache.lucene.search.Query

clone, combine, createWeight, extractTerms, getBoost, getSimilarity, mergeBooleanQueries, setBoost, toString, weight

Methods inherited from class java.lang.Object

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

Constructor Detail

BoostingQuery

public BoostingQuery(Query match,
             Query context,
             float boost)

Method Detail

rewrite

public Query rewrite(IndexReader reader)
              throws IOException

Overrides:

rewrite in class Query

Throws:

IOException

toString

public String toString(String field)

Specified by:

toString in class Query