LINQ to Entities Any() and Contains() slow with small list

Question

I\'m using EF 6 to get products from a database. The product categories are mapped as a navigation property on products, and the data is from a ProductCategory pivot table. The

Answer 1

Try first filtering out the products and only then forming your models (Product_PL and Category_PL):

var filteredProducts = db.Products.Where(p => p.Categories.Any(c => currentCategoryIdAndChildren.Contains(c.ID)))
    .Select(p => new Product_PL
    {
        id = p.ID,
        name = p.Name,
        description = p.Description,
        categories = p.Categories
                    .Select(c => new Category_PL
                    {
                        categoryid = c.ID,
                    }),
    });