Class 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 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