MEAN MongoDB Advanced Operations

Question 1

Which MongoDB aggregation stage is used to filter documents before passing them to the next stage in the pipeline?

Accepted Answer

$match

Answer

$filter

Answer

$where

Answer

$select

Question 2

What does the $lookup aggregation stage do in MongoDB?

Accepted Answer

Performs a left outer join with another collection

Answer

Creates an index on a field

Answer

Filters duplicate documents

Answer

Sorts documents by a field

Question 3

Which MongoDB index type is best suited for geospatial queries?

Accepted Answer

2dsphere

Answer

Text

Answer

Hashed

Answer

Compound

Question 4

What is the purpose of the MongoDB `explain()` method?

Accepted Answer

Returns execution plan and performance statistics for a query

Answer

Adds a description field to documents

Answer

Generates schema documentation

Answer

Lists all indexes on a collection

Question 5

In MongoDB, what does a 'covered query' mean?

Accepted Answer

A query satisfied entirely by an index without accessing documents

Answer

A query that uses the $match stage

Answer

A query with all fields projected

Answer

A query running inside a transaction

Question 6

Which MongoDB write concern value ensures acknowledgment from a majority of replica set members?

Accepted Answer

majority

Answer

1

Answer

0

Answer

all