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This code was originally made available here: [WWW] http://marc.theaimsgroup.com/?l=lucene-user&m=108058407130459&w=2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
BoostingQuery
public BoostingQuery(Query match,
Query context,
float boost)
rewrite
public Query rewrite(IndexReader reader)
throws IOException
- Description copied from class:
Query
- Expert: called to re-write queries into primitive queries. For example,
a PrefixQuery will be rewritten into a BooleanQuery that consists
of TermQuerys.
- Overrides:
rewrite
in class Query
- Throws:
IOException
hashCode
public int hashCode()
- Overrides:
hashCode
in class Query
equals
public boolean equals(Object obj)
- Overrides:
equals
in class Query
toString
public String toString(String field)
- Description copied from class:
Query
- Prints a query to a string, with
field
assumed to be the
default field and omitted.
The representation used is one that is supposed to be readable
by QueryParser
. However,
there are the following limitations:
- If the query was created by the parser, the printed
representation may not be exactly what was parsed. For example,
characters that need to be escaped will be represented without
the required backslash.
- Some of the more complicated queries (e.g. span queries)
don't have a representation that can be parsed by QueryParser.
- Specified by:
toString
in class Query
Copyright © 2000-2011 Apache Software Foundation. All Rights Reserved.