org.apache.lucene.search.function
Class ValueSourceQuery

java.lang.Object
  org.apache.lucene.search.Query
      org.apache.lucene.search.function.ValueSourceQuery

All Implemented Interfaces:

Serializable, Cloneable

Direct Known Subclasses:

FieldScoreQuery

public class ValueSourceQuery
extends Query

Expert: A Query that sets the scores of document to the values obtained from a ValueSource.

This query provides a score for each and every undeleted document in the index.

The value source can be based on a (cached) value of an indexed field, but it can also be based on an external source, e.g. values read from an external database.

Score is set as: Score(doc,query) = query.getBoost()² * valueSource(doc).

See Also:

Serialized Form

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

Constructor Summary

ValueSourceQuery(ValueSource valSrc)
Create a value source query

Method Summary

Weight	createWeight(Searcher searcher) Expert: Constructs an appropriate Weight implementation for this query.
boolean	equals(Object o) Returns true if o is equal to this.
void	extractTerms(Set<Term> terms) Expert: adds all terms occurring in this query to the terms set.
int	hashCode() Returns a hash code value for this object.
Query	rewrite(IndexReader reader) Expert: called to re-write queries into primitive queries.
String	toString(String field) Prints a query to a string, with field assumed to be the default field and omitted.

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

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

Methods inherited from class java.lang.Object

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

Constructor Detail

ValueSourceQuery

public ValueSourceQuery(ValueSource valSrc)

Create a value source query

Parameters:

valSrc - provides the values defines the function to be used for scoring

Method Detail

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

extractTerms

public void extractTerms(Set<Term> terms)

Description copied from class: Query

Expert: adds all terms occurring in this query to the terms set. Only works if this query is in its rewritten form.

Overrides:

extractTerms in class Query

createWeight

public Weight createWeight(Searcher searcher)

Description copied from class: Query

Expert: Constructs an appropriate Weight implementation for this query.

Only implemented by primitive queries, which re-write to themselves.

Overrides:

createWeight 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

equals

public boolean equals(Object o)

Returns true if o is equal to this.

Overrides:

equals in class Query

hashCode

public int hashCode()

Returns a hash code value for this object.

Overrides:

hashCode in class Query