Junior From PDF EF Core Entity Framework Core

What is the N+1 query problem?

Q: What is the N+1 query problem?

Short answer: How can lazy loading lead to it? The N+1 problem occurs when: 1 query loads N parent entities N additional queries load related entities (1 per parent) Example (lazy loading): foreach (var blog in context.Blogs) { Console.WriteLine(blog.Owner.Name); // triggers a query for each blog } This causes N+1 queries, which can hurt performance significantly. ✅ Solution: Use eager loading with .Include() to fetch everything… Real-world example (ShopNest) Loading orders with items uses .Include(o => o.Items) . Without Include, listing 50 orders can trigger 50 extra queries (N+1). Say this in the interview Define — one clear sentence (the short answer above). Example — relate it to a project like ShopNest or your real work. Trade-off — when you would not use it.

Short answer: How can lazy loading lead to it? The N+1 problem occurs when: 1 query loads N parent entities N additional queries load related entities (1 per parent) Example (lazy loading): foreach (var blog in context.Blogs) { Console.WriteLine(blog.Owner.Name); // triggers a query for each blog } This causes N+1 queries, which can hurt performance significantly. ✅ Solution: Use eager loading with .Include() to fetch everything…

Real-world example (ShopNest)

Loading orders with items uses .Include(o => o.Items). Without Include, listing 50 orders can trigger 50 extra queries (N+1).

Say this in the interview

Define — one clear sentence (the short answer above).
Example — relate it to a project like ShopNest or your real work.
Trade-off — when you would not use it.

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