SqlServerBulkInsert: SQL Server Bulk Copy for .NET

SqlServerBulkInsert is a lightweight, database-centric library for performing high-speed bulk inserts into Microsoft SQL Server. It provides a functional, fluent wrapper around the native SqlBulkCopy API using a custom IDataReader adapter to stream data directly from your domain models.

This library follows the design philosophy of my other libraries, moving away from application language-centric abstractions to a Database-first approach where the mapping is defined by the SQL types of your destination table.

Setup

SqlServerBulkInsert is available on NuGet.

You can add the following dependency to your .csproj to include it in your project:

<PackageReference Include="SqlServerBulkInsert" Version="2.0.0" />

Key Features

• Stateless Mappers: Define your schema mapping once and reuse it across multiple writers or threads.
• Database-First API: Mapping is driven by SQL Server types (e.g., NVarChar, DateTimeOffset, Int), ensuring correct metadata for the driver.
• Automatic Bracketing: Automatic escaping of schema, table, and column names using [] to prevent conflicts with reserved keywords. Handles optional schemas gracefully.
• Zero-Allocation Streaming: Uses a custom IDataReader bridge to pull data lazily from IEnumerable, keeping memory consumption flat.
• AOT Ready: Fully compatible with Native AOT and trimming in modern .NET.

Quick Start

1. Define your Data Model

Works seamlessly with C# records, structs, or traditional classes.

public record SensorData(
    Guid Id,
    string Name,
    int Temperature,
    decimal SignalStrength,
    DateTimeOffset Timestamp
);

2. Define your Mapping (Stateless & Thread-Safe)

The SqlServerMapper<T> defines the structure. It is stateless and should be instantiated once as a singleton.

private static readonly SqlServerMapper<SensorData> Mapper = 
    new SqlServerMapper<SensorData>()
        .Map("Id", SqlServerTypes.UniqueIdentifier, x => x.Id)
        .Map("Name", SqlServerTypes.NVarChar, x => x.Name)
        // Automatic handling of primitives and nullable structs
        .Map("Temperature", SqlServerTypes.Int, x => x.Temperature)
        .Map("Signal", SqlServerTypes.Decimal, x => x.SignalStrength)
        .Map("Timestamp", SqlServerTypes.DateTimeOffset, x => x.Timestamp);

3. Execute the Bulk Insert

The SqlServerBulkWriter<T> executes the bulk copy operation.

public async Task SaveDataAsync(SqlConnection conn, IEnumerable<SensorData> data)
{
    var writer = new SqlServerBulkWriter<SensorData>(Mapper)
        .WithBatchSize(5000);

    await writer.WriteAllAsync(conn, "dbo", "Sensors", data);
}