What is the BSON format?

0-2 years experience

1. 1If you need to store a JavaScript Date in MongoDB, how does BSON represent it and what does that mean for the value you retrieve?
2. 2You have a JSON document with an integer larger than 2^31‑1. When you insert it into MongoDB, what does BSON do, and how would you verify the stored type?

2-5 years experience

1. 1We noticed that a field we expected to be a string is coming back as a binary blob after a recent schema change. Walk me through how BSON encoding could cause this and how you'd debug it.
2. 2Our application serializes objects to BSON before sending them over a message queue. Explain the trade‑offs of using BSON versus plain JSON for this use case.

5-8 years experience

1. 1Design a data ingestion pipeline that writes high‑volume logs to MongoDB. How would you leverage BSON’s binary format to optimize storage and network bandwidth, and what edge cases would you watch for?
2. 2When sharding a collection that contains large binary data (e.g., images stored as BSON Binary), what performance implications does BSON have, and how would you mitigate any issues?

8+ years experience

1. 1Our organization is migrating a legacy system that stores data in a custom binary format to MongoDB. How would you plan the migration strategy considering BSON compatibility, schema evolution, and cross‑team data contracts?
2. 2Discuss the long‑term maintenance implications of relying on BSON’s type system (e.g., Decimal128, ObjectId) across multiple services written in different languages. How would you ensure consistency and avoid subtle bugs?