Class 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 Detail

      • FunctionScoreQuery

        public FunctionScoreQuery​(Query in,
                                  DoubleValuesSource source)
        Create a new FunctionScoreQuery
        Parameters:
        in - the query to wrap
        source - a source of scores
    • Method Detail

      • getWrappedQuery

        public Query getWrappedQuery()
        Returns:
        the wrapped Query
      • 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 java.io.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:
        java.io.IOException
      • rewrite

        public Query rewrite​(IndexReader reader)
                      throws java.io.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:
        java.io.IOException
      • visit

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

        public java.lang.String toString​(java.lang.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​(java.lang.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:
        Query.sameClassAs(Object), Query.classHash()
      • 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:
        Query.equals(Object)