MEAN MongoDB Advanced Operations 2

Question 1

What is the MongoDB $unwind aggregation stage used for?

Accepted Answer

Deconstructs an array field into separate documents

Answer

Merges two arrays together

Answer

Removes null fields from documents

Answer

Converts strings to arrays

Question 2

Which MongoDB feature allows you to enforce a schema on a collection?

Accepted Answer

Schema Validation with $jsonSchema

Answer

Mongoose only

Answer

Collection constraints

Answer

Document triggers

Question 3

What does the MongoDB `upsert` option do in an update operation?

Accepted Answer

Inserts a new document if no matching document exists

Answer

Updates all matching documents

Answer

Deletes and re-inserts the document

Answer

Validates the document before updating

Question 4

In MongoDB, what is a capped collection?

Accepted Answer

A fixed-size collection that overwrites oldest documents when full

Answer

A collection with a maximum document size limit

Answer

A collection with read-only access

Answer

A collection limited to 100 documents

Question 5

Which operator is used to atomically increment a numeric field in a MongoDB document?

Accepted Answer

$inc

Answer

$add

Answer

$increment

Answer

$push

Question 6

What is MongoDB's WiredTiger storage engine's default compression algorithm for documents?

Accepted Answer

Snappy

Answer

zlib

Answer

zstd

Answer

LZ4