Package org.apache.lucene.queries.function

Class FunctionScoreQuery

java.lang.Object

org.apache.lucene.search.Query

org.apache.lucene.queries.function.FunctionScoreQuery

public final class FunctionScoreQuery
extends Query

A query that wraps another query, and uses a DoubleValuesSource to replace or modify the wrapped query's score

If the DoubleValuesSource doesn't return a value for a particular document, then that document will be given a score of 0.

Constructor Summary

Constructors

Constructor	Description
FunctionScoreQuery(Query in, DoubleValuesSource source)	Create a new FunctionScoreQuery

Method Summary

Modifier and Type	Method	Description
static FunctionScoreQuery	boostByQuery(Query in, Query boostMatch, float boostValue)	Returns a FunctionScoreQuery where the scores of a wrapped query are multiplied by a boost factor if the document being scored also matches a separate boosting query.
static FunctionScoreQuery	boostByValue(Query in, DoubleValuesSource boost)	Returns a FunctionScoreQuery where the scores of a wrapped query are multiplied by the value of a DoubleValuesSource.
Weight	createWeight(IndexSearcher searcher, ScoreMode scoreMode, float boost)
boolean	equals(Object o)
DoubleValuesSource	getSource()
Query	getWrappedQuery()
int	hashCode()
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

Constructor Details

FunctionScoreQuery

public FunctionScoreQuery(Query in,
 DoubleValuesSource source)

Create a new FunctionScoreQuery

Parameters:

in - the query to wrap

source - a source of scores

Method Details

getWrappedQuery

public Query getWrappedQuery()

Returns:

the wrapped Query

getSource

public DoubleValuesSource getSource()

Returns:

the underlying value source

boostByValue

public static FunctionScoreQuery boostByValue(Query in,
 DoubleValuesSource boost)

Returns a FunctionScoreQuery where the scores of a wrapped query are multiplied by the value of a DoubleValuesSource.

If the source has no value for a particular document, the score for that document is preserved as-is.

Parameters:

in - the query to boost

boost - a DoubleValuesSource containing the boost values

boostByQuery

public static FunctionScoreQuery boostByQuery(Query in,
 Query boostMatch,
 float boostValue)

Returns a FunctionScoreQuery where the scores of a wrapped query are multiplied by a boost factor if the document being scored also matches a separate boosting query.

Documents that do not match the boosting query have their scores preserved.

This may be used to 'demote' documents that match the boosting query, by passing in a boostValue between 0 and 1.

Parameters:

in - the query to boost

boostMatch - the boosting query

boostValue - the amount to boost documents which match the boosting query

createWeight

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

Overrides:

createWeight in class Query

Throws:

IOException

rewrite

public Query rewrite(IndexReader reader)
              throws IOException

Overrides:

rewrite in class Query

Throws:

IOException

visit

public void visit(QueryVisitor visitor)

Specified by:

visit in class Query

toString

public String toString(String field)

Specified by:

toString in class Query

equals

public boolean equals(Object o)

Specified by:

equals in class Query

hashCode

public int hashCode()

Specified by:

hashCode in class Query