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​(IndexSearcher indexSearcher)
                      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.

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

        The rewrite process may be able to make use of IndexSearcher's executor and be executed in parallel if the executor is provided.

        However, if any of the intermediary queries do not satisfy the new API, parallel rewrite is not possible for any subsequent sub-queries. To take advantage of this API, the entire query tree must override this method.

        Overrides:
        rewrite in class Query
        Throws:
        java.io.IOException
        See Also:
        IndexSearcher.rewrite(Query)
      • 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 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 to those of the 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)