Handle millions of records efficiently?

Short answer: Handle millions of records efficiently What interviewers test Memory pressure awareness Streaming & batching ❌ Bad (Loads everything) var users = db.Users.ToList(); // Memory explosion ✅ Streaming (Best) await foreach (var user in db.Users.AsAsyncEnumerable())

Example code

{ Process(user); } ✅ Batching const int batchSize = 1000;
for (int i = 0; i < total; i += batchSize)
{
var batch = GetBatch(i, batchSize); ProcessBatch(batch); } Key principles Never load everything Prefer streams Control memory explicitly

Real-world example (ShopNest)

MNC rounds expect working code plus explanation. Walk through an example input from a ShopNest cart list, then discuss time and space.

Say this in the interview

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