MongoDB C100DBA Exam Practice Test Instant Access

Question 1

As per the aggregation pipeline optimization concepts, if you have a $sort followed by a $match:

AProviding these parameters in any order does not impact the performance

B$sort moves before $match

CMongoDB does not do any movements by default and will use the order provided

D$match moves before $sort

Answer : D

Question 2

Which of the following commands finds all the documents in the posts collection with post timestamp field as null?

Adb.posts.find( { post_timestamp: { $fieldtype: null } } )

Bdb.posts.find( { post_timestamp: { $type: null } } )

Cdb.posts.find( { post_timestamp : { $type; 10 > > )

Ddb.posts.find( { post_timestamp: { $fieldtype: 10 } } )

Answer : B

Question 3

Consider that you have a collection called population which has fields state and city. Which of the following query will calculate the population grouped by state and city?

Adb.population.aggregate( [{ $group: { _id: { state: '$state', city: '$city' },pop: { $pop: 1 } } }] )

Bdb.population.aggregate( [{ $group: { _id: { city: '$city' },pop: { $sum: '$pop' } } }] )Multi Document Transaction is not supported by MongoDB

Cdb.population.aggregate( [{ $group: { _id: { state: Estate', city: '$city' },pop: { $sum: '$pop' } } }] )

Ddb.population.aggregate( [{ $group: { _id: { state: Estate', city: '$city' },pop: { $sum: 1 > > >] )

Answer : C

Question 4

Which of the following are valid json documents? Select all that apply.

A{'a':l, 'b':{'b':l, 'c':'foo', 'd':'bar', 'e':[l,2,4]}}

B{'city':'New York', 'population', 7999034, boros:{'queens', 'manhattan', 'staten island', 'the bronx', u 'brooklyn'}}

C{'name':'Fred Flintstone';'occupation':'Miner';'wife':'Wilma'}

D{ }

Answer : A, D

Question 5

What is the use of mongodump and mongorestore tools?

Abackup mongodb deployment

Baudit mongodb deployment

Cperformance tune mongodb deployment

Dreplicate mongodb deployments

Answer : A

Question 6

Which of the following is incorrect statement about find and findOne operations in MongoDB?

AfindQ returns all the documents in a collection while findOne() retrieves only the first one.

Bfind.limit(l) is not the same query as findOne()

CfindOneQ returns the actual first document retrieved from a collection

DfindQ and findOneQ returns cursors to the collection documents

Answer : D

Question 7

Which of the following commands can cause the database to be locked?

AAll of the above

BInserting data

CMap-reduce

DIssuing a query

Answer : A

MongoDB Certified DBA Associate C100DBA Exam Practice Test