C100DBA Application Administration Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✓

  Multi-document transactions

  Why this is correct

  Multi-document transactions allow atomic reads and writes across multiple documents, collections, and databases in a replica set. They provide ACID guarantees for the entire transaction. Since the deployment is a replica set running MongoDB 4.2, multi-document transactions are supported and are the correct feature to achieve atomicity across multiple documents in two collections.

• ✗

  Change streams with resume tokens

  Why it's wrong here

  Change streams allow applications to listen for real-time changes to data, but they do not provide atomicity for writes. They are a notification mechanism, not a transactional one. Using change streams would not ensure that a series of reads and writes across two collections are applied atomically; they only report changes after they occur.

• ✗

  Capped collections with tailable cursors

  Why it's wrong here

  Capped collections are fixed-size collections that support high-throughput writes and tailable cursors for streaming reads. They do not provide atomicity across multiple documents or collections. Tailable cursors are for reading new data as it arrives, not for transactional updates. This feature is unrelated to the requirement for atomic multi-document operations.

• ✗

  GridFS for storing large documents

  Why it's wrong here

  GridFS is a specification for storing and retrieving files that exceed the BSON document size limit. It splits files into chunks and stores them in two collections. GridFS does not provide multi-document atomicity for arbitrary application operations; it is a storage mechanism for large files. It is not relevant to the requirement for atomic transactions across collections.