MongoDB MongoDB Indexing and Performance

Question 1

What is the default index created automatically on every MongoDB collection?

Accepted Answer

A unique index on the _id field

Answer

A compound index on all fields

Answer

A text index on the name field

Answer

A sparse index on null fields

Question 2

Which method creates an index on a MongoDB collection?

Accepted Answer

collection.createIndex()

Answer

collection.addIndex()

Answer

collection.buildIndex()

Answer

collection.newIndex()

Question 3

What does a compound index in MongoDB index?

Accepted Answer

Multiple fields within a single index

Answer

Multiple collections simultaneously

Answer

A single field with multiple data types

Answer

Compressed and uncompressed versions of a field

Question 4

What is a sparse index in MongoDB?

Accepted Answer

An index that only includes documents where the indexed field exists

Answer

An index with gaps between entries

Answer

An index on sparsely populated collections

Answer

A partial index on every other document

Question 5

Which explain() verbosity mode shows the winning query plan and execution statistics?

Accepted Answer

'executionStats'

Answer

'queryPlanner'

Answer

'allPlansExecution'

Answer

'verbose'

Question 6

What does the hint() cursor method do in MongoDB?

Accepted Answer

Forces MongoDB to use a specific index for the query

Answer

Provides query optimization hints to developers

Answer

Adds hints to the query explanation

Answer

Hints at which documents will be returned