How do you optimize performance in MongoDB?

Short answer: Indexing: Create appropriate indexes to optimize query performance. Sharding: Distribute large datasets across multiple servers. Caching: Cache frequently accessed data. Aggregation optimization: Use $match early in the aggregation pipeline. Avoid joins: MongoDB performs best when data is denormalized or embedded. Database Security

Real-world example (ShopNest)

ShopNest adds an index on Orders(CustomerId, CreatedAt) because “my recent orders” is queried constantly.

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.