org.apache.lucene.search.function
Class ValueSourceQuery

java.lang.Object
  extended by org.apache.lucene.search.Query
      extended by 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).

WARNING: The status of the search.function package is experimental. The APIs introduced here might change in the future and will not be supported anymore in such a case.

See Also:
Serialized Form

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 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 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:

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


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