RepoDb.ClickHouse 0.0.1-alpha1

RepoDb.ClickHouse — RepoDB for ClickHouse

The dedicated ClickHouse provider for RepoDB — a fast, lightweight .NET ORM that lets you use raw SQL and fluent operations side by side on the same connection. Built on top of RepoDb and ClickHouse.Driver, the official .NET ADO.NET client for ClickHouse.

Important Pages

• GitHub Home — core library and source code.
• Website — full documentation, API reference, and blog.

Community

• GitHub Issues — bug reports and feature requests.
• Microsoft Teams — live Q&A.
• GitHub Discussions — ask questions and share ideas.
• X / Twitter — news and updates.

Dependencies

• ClickHouse.Driver — the official ADO.NET client for ClickHouse that RepoDb.ClickHouse connects through, exposing ClickHouseConnection, which RepoDb.ClickHouse wraps as RepoDbClickHouseConnection (see the note above) - use that type, not the raw driver one. Include UseCustomDecimals=false in your connection string: without it, Decimal columns come back as the driver's own ClickHouseDecimal numeric type rather than a plain decimal, which RepoDb's compiled reader cannot cast to a decimal/decimal? entity property.
• RepoDb — the RepoDB core library.

Disclaimer

DateTime64 columns: ClickHouse.Driver infers a plain .NET DateTime parameter's type as DateTime (whole-second precision) - it has no visibility into the actual target column's type. Writing a DateTime value that carries fractional seconds into a DateTime64(N) column silently truncates them to whole seconds unless the parameter's type is stated explicitly. Decorate the property with [RepoDb.Attributes.Parameter.ClickHouse.ClickHouseType("Nullable(DateTime64(3))")] (matching the column's actual scale) to preserve sub-second precision on Insert/Update.

public class Customer
{
	public long Id { get; set; }

	[ClickHouseType("Nullable(DateTime64(3))")]
	public DateTime? LastUpdatedUtc { get; set; }
}

License

Apache-2.0 — Copyright © 2026 Michael Camara Pendon

Installation

Install-Package RepoDb.ClickHouse

Or visit the installation page for more options.

Get Started

Initialize the bootstrapper once at application startup:

GlobalConfiguration
    .Setup()
    .UseClickHouse();

Waiting for mutations: ClickHouse's ALTER TABLE ... UPDATE/DELETE run as asynchronous background mutations rather than synchronous statements, so a row change is not guaranteed to be visible the instant the call returns. Pass isWaitForMutationsEnabled: true to UseClickHouse() to have this waited on - honored by RepoDb.ClickHouse.BulkOperations's BulkMerge/BulkUpdate/BulkDelete/BulkDeleteByKey, which block until each mutation actually completes (up to a 5-second timeout) before returning, at the cost of extra latency per call. It defaults to false here (fire-and-forget); the underlying ClickHouseDbSetting.IsWaitForMutationsEnabled property itself defaults to true when the setting is constructed directly rather than through UseClickHouse().

Then use any RepoDB operation directly on your RepoDbClickHouseConnection, pointed at your ClickHouse server:

Query

using (var connection = new RepoDbClickHouseConnection(ConnectionString))
{
	var customer = connection.Query<Customer>(c => c.Id == 10045);
}

Insert

var customer = new Customer
{
	Id = 10046,
	FirstName = "John",
	LastName = "Doe",
	IsActive = true
};
using (var connection = new RepoDbClickHouseConnection(ConnectionString))
{
	// ClickHouse has no server-generated identity - the primary key is supplied by the caller
	connection.Insert<Customer>(customer);
}

Update

using (var connection = new RepoDbClickHouseConnection(ConnectionString))
{
	var customer = connection.Query<Customer>(10045).First();
	customer.FirstName = "John";
	customer.LastUpdatedUtc = DateTime.UtcNow;

	// Translated to an asynchronous 'ALTER TABLE ... UPDATE ... WHERE' mutation
	var affectedRows = connection.Update<Customer>(customer);
}

Delete

using (var connection = new RepoDbClickHouseConnection(ConnectionString))
{
	var customer = connection.Query<Customer>(10045).First();
	var deletedCount = connection.Delete<Customer>(customer);
}

ExecuteQuery

using (var connection = new RepoDbClickHouseConnection(ConnectionString))
{
	var customer = connection.ExecuteQuery<Customer>("SELECT * FROM `Customer` WHERE (Id = @Id);", new { Id = 10045 }).FirstOrDefault();
}

ExecuteNonQuery

using (var connection = new RepoDbClickHouseConnection(ConnectionString))
{
	var affectedRows = connection.ExecuteNonQuery("ALTER TABLE `Customer` UPDATE FirstName = @FirstName WHERE Id = @Id;", new { FirstName = "John", Id = 10045 });
}

ExecuteScalar

using (var connection = new RepoDbClickHouseConnection(ConnectionString))
{
	var count = connection.ExecuteScalar<int>("SELECT COUNT(*) FROM `Customer`;");
}

Visit the get-started page for the full guide.