Class BoostingQuery

  • All Implemented Interfaces:
    Serializable, Cloneable

    public class BoostingQuery
    extends Query
    The BoostingQuery class can be used to effectively demote results that match a given query. Unlike the "NOT" clause, this still selects documents that contain undesirable terms, but reduces their overall score: Query balancedQuery = new BoostingQuery(positiveQuery, negativeQuery, 0.01f); In this scenario the positiveQuery contains the mandatory, desirable criteria which is used to select all matching documents, and the negativeQuery contains the undesirable elements which are simply used to lessen the scores. Documents that match the negativeQuery have their score multiplied by the supplied "boost" parameter, so this should be less than 1 to achieve a demoting effect This code was originally made available here: [WWW] http://marc.theaimsgroup.com/?l=lucene-user&m=108058407130459&w=2 and is documented here: http://wiki.apache.org/lucene-java/CommunityContributions
    See Also:
    Serialized Form
    • Constructor Detail

      • BoostingQuery

        public BoostingQuery​(Query match,
                             Query context,
                             float boost)
    • 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
      • hashCode

        public int hashCode()
        Overrides:
        hashCode 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