Question

I have a document entity Student

public class Student
{
    public string Id { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public DateTime DateOfBirth { get; set; }
}

I have an index Student_ByName with a boost on the FirstName property defined as

public class Student_ByName : AbstractIndexCreationTask<Domain.Student>
{
    public Student_ByName()
    {
        Map = students => from s in students
                          select new
                                     {
                                         FirstName = s.FirstName.Boost(6), 
                                         s.LastName,
                                         s.DateOfBirth,
                                         s.Gender
                                     };
    }
}

I have the following Student document instances

{ FirstName: 'David', LastName: 'Globe', DateOfBirth: '02/04/2000' }
{ FirstName: 'Tyson', LastName: 'David', DateOfBirth: '23/10/2000' }
{ FirstName: 'David', LastName: 'James', DateOfBirth: '19/05/1996' }

then the query below does not promote rows where David is the first name to the top of the list.

var students = _session.Query<Domain.Student, Student_ByName>()
                       .Where(s => s.FirstName.StartsWith('David') || 
                                   s.LastName.StartsWith('David'))
                       .ToList();

If I change the Where clause to check for equality then the rows with David as the first name are promoted to the top of the list

.Where(s => s.FirstName == 'David' || s.LastName == 'David')
.ToList();

My question is how can I get the boost on the FirstName to work when doing a BeginsWith search.

Answer 1

This is expected, see the explanation here:

http://grokbase.com/t/lucene/java-user/022dzkexc6/prefixquery-scoring

You can do this with query time (vs index time) scoring, using:

var students = session.Advanced.LuceneQuery<Student>()
    .WhereStartsWith("FirstName", "David").Boost(3)
    .WhereStartsWith("LastName", "David")
    .ToList();