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

      public Query rewrite(IndexSearcher indexSearcher) 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.

      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:
      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 to those of the 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: