org.apache.lucene.search

Class BM25FQuery

java.lang.Object

org.apache.lucene.search.Query

org.apache.lucene.search.BM25FQuery

All Implemented Interfaces:

Accountable

public final class BM25FQuery
extends Query
implements Accountable

A Query that treats multiple fields as a single stream and scores terms as if you had indexed them as a single term in a single field. For scoring purposes this query implements the BM25F's simple formula described in: http://www.staff.city.ac.uk/~sb317/papers/foundations_bm25_review.pdf The per-field similarity is ignored but to be compatible each field must use a Similarity at index time that encodes norms the same way as SimilarityBase.computeNorm(org.apache.lucene.index.FieldInvertState).

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

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	BM25FQuery.Builder A builder for BM25FQuery.

Method Summary

Modifier and Type	Method and Description
Weight	createWeight(IndexSearcher searcher, ScoreMode scoreMode, float boost)
boolean	equals(Object other)
List<Term>	getTerms()
int	hashCode()
long	ramBytesUsed()
Query	rewrite(IndexReader reader)
String	toString(String field)
void	visit(QueryVisitor visitor)

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

classHash, sameClassAs, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.apache.lucene.util.Accountable

getChildResources

Method Detail

getTerms

public List<Term> getTerms()

toString

public String toString(String field)

Specified by:

toString in class Query

hashCode

public int hashCode()

Specified by:

hashCode in class Query

equals

public boolean equals(Object other)

Specified by:

equals in class Query

ramBytesUsed

public long ramBytesUsed()

Specified by:

ramBytesUsed in interface Accountable

rewrite

public Query rewrite(IndexReader reader)
              throws IOException

Overrides:

rewrite in class Query

Throws:

IOException

visit

public void visit(QueryVisitor visitor)

Overrides:

visit in class Query

createWeight

public Weight createWeight(IndexSearcher searcher,
                           ScoreMode scoreMode,
                           float boost)
                    throws IOException

Overrides:

createWeight in class Query

Throws:

IOException