Indexes: Sorting & Collation

Starting from version 4.0, RavenDB automatically determines sorting based on an indexed value. All values will have a capability to be sorted lexicographically. Numerical values will also be sortable by their double and long value.

Date types

Dates are written to the index in a form which preserves lexicography order, and is readable by both human and machine (like so: 2011-04-04T11:28:46.0404749+03:00). This requires no user intervention.

Example

Please read our dedicated article describing sorting capabilities when queries are executed. It can be found here.

Collation

RavenDB supports using collations for documents sorting and indexing. You can setup a specific collation for an index field, so you can sort based of culture specific rules.

The following is an example of an index definition which allows sorting based on the Swedish lexical sorting rules:

public class Products_ByName : AbstractIndexCreationTask<Product>
{
    public Products_ByName()
    {
        Map = products => from product in products
                          select new
                          {
                              product.Name
                          };

        Analyzers.Add(x => x.Name, "Raven.Server.Documents.Indexes.Persistence.Lucene.Analyzers.Collation.Cultures.SvCollationAnalyzer, Raven.Server");
    }
}

private class Products_ByName : AbstractJavaScriptIndexCreationTask
{
    public Products_ByName()
    {
        Maps = new HashSet<string>
        {
            @"map('products', function (u){
                            return {
                                Name: u.Name,
                                _: {$value: u.Name, $name:'AnalyzedName'}
                            };
                        })",
        };
        Fields = new Dictionary<string, IndexFieldOptions>
        {
            {
                "AnalyzedName", new IndexFieldOptions()
                {
                    Indexing = FieldIndexing.Search,
                    Analyzer = "StandardAnalyzer"
                }
            }
        };
    }
    public class Result
    {
        public string AnalyzedName { get; set; }
    }
}

In general, you can sort using Raven.Database.Indexing.Collation.Cultures.<two-letters-culture-name>CollationAnalyzer, and all the cultures supported by the .NET framework are supported.