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.

  • Field Details

  • 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
      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
      scoreMode - How the produced scorers will be consumed.
      boost - The boost that is propagated by the parent queries.
      Throws:
      IOException
    • 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.

      Callers are expected to call rewrite multiple times if necessary, until the rewritten query is the same as the original query.

      Overrides:
      rewrite in class Query
      Throws:
      IOException
      See Also:
    • visit

      public void visit(QueryVisitor visitor)
      Description copied from class: Query
      Recurse through the query tree, visiting any child queries
      Specified by:
      visit in class Query
      Parameters:
      visitor - a QueryVisitor to be called by each query in the tree
    • 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.
      Specified by:
      toString in class Query
    • equals

      public boolean equals(Object o)
      Description copied from class: Query
      Override and implement query instance equivalence properly in a subclass. This is required so that QueryCache works properly.

      Typically a query will be equal to another only if it's an instance of the same class and its document-filtering properties are identical that other instance. Utility methods are provided for certain repetitive code.

      Specified by:
      equals in class Query
      See Also:
    • hashCode

      public int hashCode()
      Description copied from class: Query
      Override and implement query hash code properly in a subclass. This is required so that QueryCache works properly.
      Specified by:
      hashCode in class Query
      See Also: