LINQ Where Clause Performance guide with Large Data Set in EF Core 6
I'm collaborating on a project where I'm stuck on something that should probably be simple..... I am experiencing important performance optimization when applying a `Where` clause in a LINQ query against a large dataset using Entity Framework Core 6. My query looks something like this: ```csharp var filteredItems = await context.Items .Where(item => item.Quantity > 10 && item.Status == "Active") .ToListAsync(); ``` This query runs fine with smaller datasets, but when I try to execute it against a table with over 1 million records, it takes a very long time to complete, often timing out. I have ensured that there is an index on the `Quantity` and `Status` columns. I tried breaking the query down further and executing it step by step: ```csharp var activeItems = await context.Items .Where(item => item.Status == "Active") .ToListAsync(); var filteredItems = activeItems.Where(item => item.Quantity > 10).ToList(); ``` This approach seems to help a little, but it's still not performant enough for real-world usage. I also tried adding `.AsNoTracking()` to the query to see if that made a difference, but it didn't. Additionally, I checked SQL Server Profiler, and the generated SQL is not utilizing the indexes effectively. It seems to be doing a full table scan when filtering by `Quantity`. I am using SQL Server 2019 and EF Core 6.0. Is there a better way to optimize this LINQ query, or any best practices I might be missing? Any suggestions would be greatly appreciated! This is part of a larger service I'm building. This is part of a larger web app I'm building. Could this be a known issue? This issue appeared after updating to Csharp stable. I appreciate any insights! This is part of a larger application I'm building. Has anyone dealt with something similar? Hoping someone can shed some light on this.