Sort clauses for collections (C#)
Many Data API commands use sort clauses to sort documents by field values, or to perform vector search.
You must use & to escape any . or & in field names in a sort clause.
Dot notation, which is used to reference nested fields, should not be escaped.
For more information, see Work with . and & in field names (C#).
Sort by field values
Use a sort clause to sort documents by field values in ascending or descending order.
When sorting by multiple fields, the order of the fields in the sort clause controls the order of the sorting.
Sort clauses can use only indexed fields. If you apply selective indexing when you create a collection, you cannot reference non-indexed fields in sort queries.
You can’t sort the $lexical field in ascending or descending order.
Instead, you must sort by lexicographical match.
The following example uses untyped documents, but you can use strongly-typed classes for compile-time checks and IntelliSense. For more information and examples, see Custom typing for collections.
using System.Text.Json;
using DataStax.AstraDB.DataApi;
using DataStax.AstraDB.DataApi.Collections;
using DataStax.AstraDB.DataApi.Core;
using DataStax.AstraDB.DataApi.Core.Query;
namespace Examples;
public class Program
{
static async Task Main()
{
// Get an existing collection
var client = new DataAPIClient(
new CommandOptions() { Destination = DataAPIDestination.HCD }
);
var database = client.GetDatabase(
"API_ENDPOINT",
DataAPIClient.UsernamePasswordTokenProvider(
"USERNAME",
"PASSWORD"
),
"KEYSPACE_NAME"
);
var collection = database.GetCollection("COLLECTION_NAME");
// Find documents
var filterBuilder = Builders<Document>.CollectionFilter;
var filter = filterBuilder.Eq("metadata.language", "English");
var sort = Builders<Document>
.CollectionSort.Ascending("rating")
.Descending("title");
var result = collection.Find(
filter,
new CollectionFindOptions<Document>() { Sort = sort }
);
await foreach (var document in result)
{
Console.WriteLine(JsonSerializer.Serialize(document));
}
}
}Sort by vector similarity (vector search)
To find the documents whose $vector value is most similar to a given vector, use a sort clause with the vector embeddings that you want to match.
For more information, see Find data with vector search.
Vector search is only available for vector-enabled collections.
For more information, see Create a collection that can store vector embeddings and $vector in collections (C#).
Example sorting against a search vector
The following example uses untyped documents, but you can use strongly-typed classes for compile-time checks and IntelliSense. For more information and examples, see Custom typing for collections.
using System.Text.Json;
using DataStax.AstraDB.DataApi;
using DataStax.AstraDB.DataApi.Collections;
using DataStax.AstraDB.DataApi.Core;
using DataStax.AstraDB.DataApi.Core.Query;
namespace Examples;
public class Program
{
static async Task Main()
{
// Get an existing collection
var client = new DataAPIClient(
new CommandOptions() { Destination = DataAPIDestination.HCD }
);
var database = client.GetDatabase(
"API_ENDPOINT",
DataAPIClient.UsernamePasswordTokenProvider(
"USERNAME",
"PASSWORD"
),
"KEYSPACE_NAME"
);
var collection = database.GetCollection("COLLECTION_NAME");
// Find documents
var embeddings = new float[] { 0.08f, -0.62f, 0.39f };
var result = collection.Find(
new CollectionFindOptions<Document>()
{
Sort = Builders<Document>.CollectionSort.Vector(embeddings),
}
);
await foreach (var document in result)
{
Console.WriteLine(JsonSerializer.Serialize(document));
}
}
}Sort by lexicographical matching (BM25-based ranking)
Sort on the $lexical field to the documents whose $lexical field value is most relevant to a given string of space-separated keywords or terms.
This is only available for collections with lexical enabled. For more information, see Create a collection that supports lexicographical matching.
When sorting on the $lexical field, you can’t include additional sort clauses.
The following example uses untyped documents, but you can use strongly-typed classes for compile-time checks and IntelliSense. For more information and examples, see Custom typing for collections.
using System.Text.Json;
using DataStax.AstraDB.DataApi;
using DataStax.AstraDB.DataApi.Collections;
using DataStax.AstraDB.DataApi.Core;
using DataStax.AstraDB.DataApi.Core.Query;
namespace Examples;
public class Program
{
static async Task Main()
{
// Get an existing collection
var client = new DataAPIClient(
new CommandOptions() { Destination = DataAPIDestination.HCD }
);
var database = client.GetDatabase(
"API_ENDPOINT",
DataAPIClient.UsernamePasswordTokenProvider(
"USERNAME",
"PASSWORD"
),
"KEYSPACE_NAME"
);
var collection = database.GetCollection("COLLECTION_NAME");
// Find a document
var result = collection.Find(
new CollectionFindOptions<Document>()
{
Sort = Builders<Document>.CollectionSort.Lexical(
"tree hill grassy"
),
}
);
await foreach (var document in result)
{
Console.WriteLine(JsonSerializer.Serialize(document));
}
}
}Commands that support sort clauses for collections
There are many Data API commands that support sort clauses for collections.
For more examples of sort clauses, see the reference for the command that you want to run:
