Boost Search Results

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

• In order to prioritize results,
  you can provide a boost value to the searched terms which will be integrated with the basic score.

• Usually, the higher the boost value, the more relevant the term will be,
  resulting in a higher ranking of its matching document in the results.

• In this page:

  • Boost results - when making a full-text search
  • Boost results - when querying with where clause
  • Get resulting score

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.

• Query
• Query_async
• DocumentQuery
• RQL

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.
//
// * Matching documents with 'Italian' will be listed FIRST in the results,
//   before those with 'English'.
// 
// * Search is case-insensitive.

List<Employee> employees = await asyncSession
   // 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)
  .ToListAsync();

// * Results will contain all Employee documents that have
//   EITHER 'English' OR 'Italian' in their 'Notes' field.
//
// * Matching documents with 'Italian' will be listed FIRST in the results,
//   before those with 'English'.
// 
// * Search is case-insensitive.

List<Employee> employees = session.Advanced
   // Make a dynamic full-text search DocumentQuery on 'Employees' collection
  .DocumentQuery<Employee>()
   // This search predicate will use the default boost value of 1
  .Search(x => x.Notes, "English")
   // This search predicate will use a boost value of 10 
  .Search(x => x.Notes, "Italian")
   // Call 'Boost' to set the boost value of the previous 'Search' call
  .Boost(10)
  .ToList();

// * Results will contain all Employee documents that have
//   EITHER 'English' OR 'Italian' in their 'Notes' field.
//
// * Matching documents with 'Italian' will be listed FIRST in the results,
//   before those with 'English'.
// 
// * Search is case-insensitive.

from "Employees" where
search(Notes, "English") or boost(search(Notes, "Italian"), 10)

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.

• DocumentQuery
• DocumentQuery_async
• RQL

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.
//
// * Matching documents the end-with 'OP' will be listed FIRST.
//   Matching documents that start-with 'P' will then be listed.
//   Matching documents that start-with 'O' will be listed LAST.
// 
// * Search is case-insensitive.

List<Company> companies = await asyncSession.Advanced
   // Make a dynamic DocumentQuery on 'Companies' collection
  .AsyncDocumentQuery<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)
  .ToListAsync();

// * Results will contain all Company documents that either
//   (start-with 'O') OR (start-with 'P') OR (end-with 'OP') in their 'Name' field.
//
// * Matching documents the end-with 'OP' will be listed FIRST.
//   Matching documents that start-with 'P' will then be listed.
//   Matching documents that start-with 'O' will be listed LAST.
// 
// * Search is case-insensitive.

from "Companies" where
boost(startsWith(Name, "O"), 10) or
boost(startsWith(Name, "P"), 50) or
boost(endsWith(Name, "OP"), 90)

Get resulting score

• The score can be retrieved by either:

  • Request to include explanations when making the query.
    See include query explanations.

  • Get the metadata of the resulting entities that were loaded to the session.
    See example below.

// Make a query:
// =============

List<Employee> employees = session
  .Query<Employee>()
  .Search(x => x.Notes, "English")
  .Search(x => x.Notes, "Italian", boost: 10)
  .ToList();

// Get the score:
// ==============

// Call 'GetMetadataFor', pass an entity from the resulting employees list
var metadata = session.Advanced.GetMetadataFor(employees[0]);

// Score is available in the '@index-score' metadata property
var score = metadata[Constants.Documents.Metadata.IndexScore];