Optimising Database Performance Using Dapper

Dapper is a lightweight micro-ORM for .NET that offers high-speed data access while keeping things simple. Unlike full-fledged ORMs like Entity Framework, Dapper focuses on raw SQL execution with minimal overhead. If you're working on an application where performance matters, Dapper can be a great choice.

In this article, we'll go over practical ways to get the best performance when using Dapper.

1. Write Efficient Queries

Since Dapper runs raw SQL, poorly written queries can slow things down. Here are some best practices:

• Select only the columns you need (SELECT column1, column2 FROM Table instead of SELECT *).
• Use indexes on frequently searched columns.
• Keep joins simple and denormalise where necessary.
• Use stored procedures for repetitive queries.
• Check performance with execution plans (EXPLAIN in MySQL/PostgreSQL, SHOW EXECUTION PLAN in SQL Server).

Example:

var sql = "SELECT Id, Name FROM Customers WHERE IsActive = @IsActive";
var customers = connection.Query<Customer>(sql, new { IsActive = true }).ToList();

2. Use Parameterised Queries

Always use parameterised queries to prevent SQL injection and improve efficiency:

var sql = "SELECT * FROM Orders WHERE CustomerId = @CustomerId";
var orders = connection.Query<Order>(sql, new { CustomerId = 1 }).ToList();

Dapper automatically handles parameters, making your queries safer and faster.

3. Reduce Database Calls with QueryMultiple

If you need to run multiple queries at once, QueryMultiple can help reduce database round trips:

var sql = "SELECT * FROM Customers; SELECT * FROM Orders";
using (var multi = connection.QueryMultiple(sql))
{
    var customers = multi.Read<Customer>().ToList();
    var orders = multi.Read<Order>().ToList();
}

This approach improves efficiency by fetching multiple result sets in a single request.

4. Reuse Connections Efficiently

Dapper relies on ADO.NET under the hood, which benefits from connection pooling. To get the most out of it:

• Reuse IDbConnection instances where possible.
• Open and close connections efficiently to avoid unnecessary resource usage.

Example:

using (var connection = new SqlConnection(connectionString))
{
    var customers = connection.Query<Customer>("SELECT * FROM Customers").ToList();
}

Using using ensures connections are properly disposed of when no longer needed.

5. Optimise Bulk Inserts

Dapper isn't built for bulk inserts, but you can speed things up using SqlBulkCopy for large datasets:

using (var bulkCopy = new SqlBulkCopy(connectionString))
{
    bulkCopy.DestinationTableName = "Customers";
    bulkCopy.WriteToServer(dataTable);
}

For smaller inserts, consider running multiple INSERT statements in a single query. If you're using SQL Server, Table-Valued Parameters (TVPs) can help:

var dt = new DataTable();
dt.Columns.Add("Id", typeof(int));
dt.Columns.Add("Name", typeof(string));


using (var connection = new SqlConnection(connectionString))
{
    var parameters = new { Customers = dt.AsTableValuedParameter("CustomerType") };
    connection.Execute("INSERT INTO Customers (Id, Name) SELECT Id, Name FROM @Customers", parameters);
}

6. Use Asynchronous Queries

Using Dapper’s async methods (QueryAsync, ExecuteAsync) prevents blocking, making your application more scalable:

var sql = "SELECT * FROM Customers WHERE IsActive = @IsActive";
var customers = await connection.QueryAsync<Customer>(sql, new { IsActive = true });

Async methods are especially useful in web applications handling many database requests simultaneously.

7. Simplify CRUD Operations with Dapper.Contrib

Dapper.Contrib adds helper methods for common CRUD operations. While it's convenient, it may add some overhead compared to raw SQL:

using Dapper.Contrib.Extensions;
var customer = new Customer { Name = "John Doe" };
connection.Insert(customer);

If performance is critical, writing direct SQL queries is usually faster.

8. Dapper vs. Entity Framework

Dapper and Entity Framework serve different purposes:

Feature	Dapper	Entity Framework
Performance	⚡ Fast	🐢 Slower due to abstraction
Ease of Use	Medium	High (Auto Migrations, LINQ)
Flexibility	High (Full SQL control)	Medium (ORM with some SQL support)
Best for	High-performance apps, microservices	Complex data models, rapid development

If raw performance is your top priority, go with Dapper. If you need advanced data modelling features, Entity Framework might be a better fit.

Conclusion

Dapper dances gracefully between speed and simplicity. Crafting sharp queries, harnessing connection pooling, leveraging asynchronous operations, and fine-tuning bulk processes, all lead to peak performance in your .Enter the realm of NET applications, where best practices reign supreme. Navigate the chaos to construct a dynamic, adaptable, and swift system, all the while embracing simplicity and maintainability.

Comments

[Spyros Ponaris]

Dapper is fast and gives you full control. EF Core is a framework and easy to use.
EF Core should for standard CRUD operations and data modeling, and Dapper for high-performance queries and bulk operations. Combining both gives you the best balance of speed and flexibility.