MongoDB MongoDB Aggregation Framework

Question 1

Which aggregation stage filters documents to pass only those matching specified conditions to the next stage?

Accepted Answer

$match

Answer

$group

Answer

$project

Answer

$filter

Question 2

What is the primary purpose of the $group stage in aggregation?

Accepted Answer

To group documents by a specified identifier and compute aggregate values

Answer

To join multiple collections

Answer

To sort documents into groups

Answer

To create new collections

Question 3

Which aggregation accumulator returns the sum of numeric values in a group?

Accepted Answer

$sum

Answer

$total

Answer

$add

Answer

$count

Question 4

What does the $project stage do in an aggregation pipeline?

Accepted Answer

Passes documents with requested fields to the next stage

Answer

Creates a new database projection

Answer

Projects future data trends

Answer

Adds geospatial projections

Question 5

Which stage limits the number of documents passed to the next aggregation stage?

Accepted Answer

$limit

Answer

$skip

Answer

$restrict

Answer

$max

Question 6

What is the purpose of the $unwind stage in aggregation?

Accepted Answer

Deconstructs an array field to output one document per array element

Answer

Reverses a previous sort

Answer

Unwraps nested objects into flat documents

Answer

Removes duplicate documents