MEAN MongoDB Advanced Operations 3

Question 1

What is the purpose of MongoDB transactions introduced in version 4.0?

Accepted Answer

Provide ACID guarantees across multiple documents and collections

Answer

Improve single-document write speed

Answer

Enable cross-database replication

Answer

Enforce document schema validation

Question 2

Which MongoDB command is used to initiate a replica set?

Accepted Answer

rs.initiate()

Answer

replicaset.start()

Answer

db.initReplica()

Answer

mongo.replica.init()

Question 3

In MongoDB, what does the $group aggregation stage do?

Accepted Answer

Groups documents by a specified expression and accumulates values

Answer

Sorts documents into groups by field value

Answer

Removes duplicate documents

Answer

Partitions documents into buckets

Question 4

What is the default port MongoDB listens on?

Accepted Answer

27017

Answer

28017

Answer

3306

Answer

5432

Question 5

Which MongoDB feature allows data to automatically expire after a set time?

Accepted Answer

TTL (Time-To-Live) indexes

Answer

Capped collections

Answer

Change streams

Answer

Expiry validators

Question 6

What does the MongoDB $project aggregation stage do?

Accepted Answer

Shapes output documents by including, excluding, or renaming fields

Answer

Creates new collections from query results

Answer

Projects indexes onto query results

Answer

Filters documents by field existence