C100DBA Online Practice Questions and Answers

Which of the following is supported by MongoDB?

A. Transaction Management

B. ACID Transactions

C. Journaling

D. Relationships between Collections (Primary Key Foreign Key)

Which node in a replica set does accept write operation?

A. arbiter

B. hidden

C. primary

D. secondary

Using an arbiter allows one to easily ensure an odd number of voters in replica sets. Why is this important?

A. To help in disaster recovery

B. To protect agains network partitions

C. To enable certain read preference settings

D. To add greather redundancy

E. For more efficient backup operations

Dada una coleccion, cuales devuelve con la siguiente query db.coleccion.find ({nombre:"ruben",apellido:"gomez"},{nombre:l,apellido:l,aficion:l});

A. { "-id" : Objectld("580a42b5dfblb5al7427d302"), "nombre" : "ruben", "apellido" : "gomez", "aficion" : v u "flipar" }

B. { "_id" : Objectld("580a42acdfblb5al7427d301"), "nombre" : "Luis", "apellido" : "gomez", "aficion" : u "flipar" }

C. { "_id" : Objectld("580a42acdfblb5al7427d301"), "nombre" : "ruben", "apellido" : "Pablo" , "aficion" : u "flipar"}

D. { "_id" : Objectld("580a42acdfblb5al7427d301"), "nombre" : "ruben", "apellido" : "gomez" >

Which are the ONLY ways to project portions of an array?

A. $slice

B. $

C. All of the above

D. $ elemMatch

Which of the following aggregate commands in MongoDB uses a pipeline approach with the goals of improving the aggregation performance?

A. mapReduce

B. group

C. aggregate

D. All of the above

Consider the following documents:

You perform the following query;

How many documents will be updated by the query?

A. 0

B. 1

C. 2

D. 3

E. 5

Addding the index {a:l} can potentially decrease the speed of which of the following operations? Check all that apply.

A. db.collection.update({b:456>, {$inc: {a:l> })

B. db.collection.find( {a : 232} )

C. db.collection.insert( { a:341})

Which of the following needs to be performed prior to initiate backup on a sharded cluster?

A. db.stopBalancer( )

B. sh.stopServer( )

C. db.stopServer( )

D. sh.stopBalancer( )

Which of the following about Capped Collections is correct?

A. Fixed Size

B. Only "Fixed Size" and "High-throughput operations that insert and retrieve documents based on insertion order"

C. High-throughput operations that insert and retrieve documents based on insertion order

D. If the allocated space for a capped collection exceeds, it stops inserting new documents