Sort clauses for tables (C#)
Many Data API commands use sort clauses to sort rows by column values or to perform vector search.
Sort by column values
Use a sort clause to sort rows by column values in ascending or descending order.
When sorting by multiple columns, the order of the columns in the sort clause controls the order of the sorting.
For best performance, only sort on indexed columns, partition keys, and clustering keys. Otherwise, the Data API can perform in-memory sorting, which can have performance implications.
-
Typed
-
Untyped
You can manually define a client-side type for your table to help statically catch errors. For more information and examples, see Custom typing for tables.
using System.Text.Json;
using DataStax.AstraDB.DataApi;
using DataStax.AstraDB.DataApi.Core;
using DataStax.AstraDB.DataApi.Core.Query;
using DataStax.AstraDB.DataApi.Tables;
namespace Examples;
public class Book
{
[ColumnPrimaryKey(1)]
[ColumnName("title")]
public string Title { get; set; } = null!;
[ColumnPrimaryKey(2)]
[ColumnName("author")]
public string Author { get; set; } = null!;
[ColumnName("rating")]
public float? Rating { get; set; }
}
public class Program
{
static async Task Main()
{
// Get an existing table
var client = new DataAPIClient(
new CommandOptions() { Destination = DataAPIDestination.HCD }
);
var database = client.GetDatabase(
"API_ENDPOINT",
DataAPIClient.UsernamePasswordTokenProvider(
"USERNAME",
"PASSWORD"
),
"KEYSPACE_NAME"
);
var table = database.GetTable<Book>("TABLE_NAME");
// Find rows
var results = table.Find(
new TableFindOptions<Book>()
{
Sort = Builders<Book>
.TableSort.Ascending(b => b.Rating)
.Descending(b => b.Title),
}
);
await foreach (var row in results)
{
Console.WriteLine(JsonSerializer.Serialize(row));
}
}
}If you don’t pass a type parameter, the collection or table remains untyped. This is a more flexible but less type-safe option.
using System.Text.Json;
using DataStax.AstraDB.DataApi;
using DataStax.AstraDB.DataApi.Core;
using DataStax.AstraDB.DataApi.Core.Query;
using DataStax.AstraDB.DataApi.Tables;
namespace Examples;
public class Program
{
static async Task Main()
{
// Get an existing table
var client = new DataAPIClient(
new CommandOptions() { Destination = DataAPIDestination.HCD }
);
var database = client.GetDatabase(
"API_ENDPOINT",
DataAPIClient.UsernamePasswordTokenProvider(
"USERNAME",
"PASSWORD"
),
"KEYSPACE_NAME"
);
var table = database.GetTable("TABLE_NAME");
// Find rows
var results = table.Find(
new TableFindOptions<Row>()
{
Sort = Builders<Row>
.TableSort.Ascending("rating")
.Descending("title"),
}
);
await foreach (var row in results)
{
Console.WriteLine(JsonSerializer.Serialize(row));
}
}
}Sort by vector similarity (vector search)
To find the rows with a vector column value that 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.
The vector column must be indexed.
If your table has multiple vector columns, you can only sort on one vector column at a time.
Vector search returns up to 1000 rows per search operation, unless you specify a lower limit.
Example sorting against a search vector
-
Typed
-
Untyped
You can manually define a client-side type for your table to help statically catch errors. For more information and examples, see Custom typing for tables.
using System.Text.Json;
using DataStax.AstraDB.DataApi;
using DataStax.AstraDB.DataApi.Core;
using DataStax.AstraDB.DataApi.Core.Query;
using DataStax.AstraDB.DataApi.Tables;
namespace Examples;
public class Book
{
[ColumnPrimaryKey(1)]
[ColumnName("title")]
public string Title { get; set; } = null!;
[ColumnPrimaryKey(2)]
[ColumnName("author")]
public string Author { get; set; } = null!;
[ColumnVector(5)]
[ColumnName("summary_genres_vector")]
public object? SummaryGenresVector { get; set; }
}
public class Program
{
static async Task Main()
{
// Get an existing table
var client = new DataAPIClient(
new CommandOptions() { Destination = DataAPIDestination.HCD }
);
var database = client.GetDatabase(
"API_ENDPOINT",
DataAPIClient.UsernamePasswordTokenProvider(
"USERNAME",
"PASSWORD"
),
"KEYSPACE_NAME"
);
var table = database.GetTable<Book>("TABLE_NAME");
// Find rows
var embeddings = new float[] { 0.08f, -0.62f, 0.39f };
var results = table.Find(
new TableFindOptions<Book>()
{
Sort = Builders<Book>.TableSort.Vector(
b => b.SummaryGenresVector,
embeddings
),
}
);
await foreach (var row in results)
{
Console.WriteLine(JsonSerializer.Serialize(row));
}
}
}If you don’t pass a type parameter, the collection or table remains untyped. This is a more flexible but less type-safe option.
using System.Text.Json;
using DataStax.AstraDB.DataApi;
using DataStax.AstraDB.DataApi.Core;
using DataStax.AstraDB.DataApi.Core.Query;
using DataStax.AstraDB.DataApi.Tables;
namespace Examples;
public class Program
{
static async Task Main()
{
// Get an existing table
var client = new DataAPIClient(
new CommandOptions() { Destination = DataAPIDestination.HCD }
);
var database = client.GetDatabase(
"API_ENDPOINT",
DataAPIClient.UsernamePasswordTokenProvider(
"USERNAME",
"PASSWORD"
),
"KEYSPACE_NAME"
);
var table = database.GetTable("TABLE_NAME");
// Find rows
var embeddings = new float[] { 0.08f, -0.62f, 0.39f };
var results = table.Find(
new TableFindOptions<Row>()
{
Sort = Builders<Row>.TableSort.Vector(
"summary_genres_vector",
embeddings
),
}
);
await foreach (var row in results)
{
Console.WriteLine(JsonSerializer.Serialize(row));
}
}
}Commands that support sort clauses for tables
There are many Data API commands that support sort clauses for tables.
For more examples of sort clauses, see the reference for the command that you want to run:
