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Boost Search Results

  • When querying with some filtering conditions,
    a basic score is calculated for each document in the results by the underlying engine.

  • Providing a boost value to some fields allows you to prioritize the resulting documents.
    The boost value is integrated with the basic score, making the document rank higher.

  • Boosting can be achieved in the following ways:

    • At query time:
      Apply a boost factor to searched terms at query time - as described in this article.

    • Via index definition:
      Apply a boost factor in your index definition - see this boosting indexing article.

  • The automatic ordering of the results by the score is configurable.
    Learn more here: automatic score-based ordering

  • The calculated score details of the results can be retrieved if needed.
    Learn more here: get resulting score

  • In this page:

Boost results - when making a full-text search​

When making a full-text search with the Search() method then boosting can be applied
to both Query and DocumentQuery.

List<Employee> employees = session
   // Make a dynamic full-text search Query on 'Employees' collection
  .Query<Employee>()
   // This search predicate will use the default boost value of 1
  .Search(x => x.Notes, "English")
   // * Pass the boost value using the 'boost' parameter
   // * This search predicate will use a boost value of 10
  .Search(x => x.Notes, "Italian", boost: 10)
  .ToList();

// * Results will contain all Employee documents that have
//   EITHER 'English' OR 'Italian' in their 'Notes' field (case-insensitive).
//
// * Matching documents that contain 'Italian' will get a HIGHER score
//   than those that contain 'English'.
//
// * Unless configured otherwise, the resulting documents will be ordered by their score.

Boost results - when querying with where clause​

When querying with Where clauses (using an OR condition in between) then boosting can be applied
only with DocuemtQuery.

List<Company> companies = session.Advanced
   // Make a dynamic DocumentQuery on 'Companies' collection
  .DocumentQuery<Company>()
   // Define a 'Where' condition
  .WhereStartsWith(x => x.Name, "O")
   // Call 'Boost' to set the boost value of the previous 'Where' predicate
  .Boost(10)
   // Call 'OrElse' so that OR operator will be used between statements
  .OrElse()
  .WhereStartsWith(x => x.Name, "P")
  .Boost(50)
  .OrElse()
  .WhereEndsWith(x => x.Name, "OP")
  .Boost(90)
  .ToList();

// * Results will contain all Company documents that either
//   (start-with 'O') OR (start-with 'P') OR (end-with 'OP') in their 'Name' field (case-insensitive).
//
// * Matching documents that end-with 'OP' will get the HIGHEST scores.
//   Matching documents that start-with 'O' will get the LOWEST scores. 
//
// * Unless configured otherwise, the resulting documents will be ordered by their score.