Profiling ASP.NET Core 6 Application for Performance Bottlenecks in Local Development
This might be a silly question, but While profiling a local ASP.NET Core 6 application, I've noticed some performance bottlenecks that I’m trying to address. The application serves as a REST API, and I've instrumented it with middleware to log request timings. Despite this, response times for certain endpoints are unexpectedly high, even when tested under light load. One particular endpoint, `/api/orders`, retrieves order data and related customer information from a PostgreSQL database using Entity Framework Core. Here’s the relevant snippet: ```csharp public async Task<IActionResult> GetOrders() { var orders = await _context.Orders.Include(o => o.Customer).ToListAsync(); return Ok(orders); } ``` Upon inspecting the SQL queries generated by EF Core, I noticed that the `Include` statement could be causing the issue by loading all related customer data, even when it’s not necessary. To mitigate this, I tried using projection with `Select`: ```csharp public async Task<IActionResult> GetOrders() { var orders = await _context.Orders .Select(o => new { o.Id, o.OrderDate, CustomerName = o.Customer.Name }) .ToListAsync(); return Ok(orders); } ``` This change improved performance, but I’m still observing delays when the dataset grows larger. Additionally, I'm caching some of the results, but I want to refine this further. Another approach I considered is implementing pagination to avoid loading excessive records at once, yet I’m unsure how to handle that effectively with EF Core. Here's how I attempted pagination: ```csharp public async Task<IActionResult> GetOrders(int page = 1, int pageSize = 10) { var orders = await _context.Orders.Skip((page - 1) * pageSize).Take(pageSize).ToListAsync(); return Ok(orders); } ``` After applying this, response times improved slightly, but I suspect that the N+1 query problem still lurks beneath the surface when accessing related entities. Profiling with SQL Server Profiler revealed multiple queries being executed for fetching customer details per order, which is suboptimal. I’m intrigued by suggestions involving batch fetching or even using raw SQL queries for particular cases, but I'm unsure how to implement that cleanly without losing the advantages of EF Core. What practices or patterns could I adopt to enhance the performance of this API further? Are there specific techniques in EF Core that might help reduce the number of queries or optimize data retrieval without adding excessive complexity to my code?