MongoDB c100dba practice test

Question 1

Which of the following statements are true about the $match pipeline operator? Check all that apply.

• A. You should use it early as possible in the pipeline
• B. It can be used as many time as needed.
• C. It has a sintax similar to findQ commands.

Question 2

Consider the following document:
> db.c.find()
{ "_id" : 12, b : [ 3, 5, 7, 2, 1, -4, 3, 12 ] }
Which of the following queries on the "c" collection will return only the first five elements of the
array in the "b"
field? E.g.,
Document you want returned by your query:
{ "_id" : 12, "b" : [ 3, 5, 7, 2, 1 ] >

• A. db.c.find( { > , { b : { $slice : [ 0 , 5 ] } } )
• B. db.c.find( { b : [ 0 , 5 ] > )
• C. db.c.find( { > , { b : { $substr[ 0 , 5 ] > > )
• D. db.c.find( { > , { b : [ 0, 1, 2, 3, 4, 5 ] > )
• E. db.c.find( { > , { b : [ 0 , 5 ] > )

Question 3

What tool do you use if you want to extract a CSV from mongo?

Question 4

Which of the following is true of the mechanics of replication in MongoDB? Check all that apply.

• A. Members of a replica set may replicate data from any other data-bearing member of the set by default
• B. Clients read from the nearest member of a replica ser by default
• C. Operations on the primary are recorded in a capped collection called the oplog

Question 5

What tool do you use to see if you have a problem in the consumption of disk I / 0?

Question 6

Suposse tou have the following collection with only 2 documents:

If you run an aggregation query and use { $unwind: "$traits" } as the first stage, how many
documents will be passed to the next stage of the aggregation pipeline?

• A. 3
• B. 5
• C. 4
• D. 2
• E. 1

Question 7

What tool would you use if you want to save a gif file in mongo?

Question 8

Which features of relational database management systems were deliberately omitted in MongoDB
and help us to obtain horizontal scalability? Check all that apply.

• A. Multi-statement transactions
• B. Joins
• C. Authentication

Question 9

In order to ensure that you can maintain high availability in the face of server failure, you should
implement which of the following?

• A. Sharding
• B. Properly defined user roles
• C. Replication
• D. Put indexes on all of your documents
• E. The proper storage engine

Question 10

Which of the following is a valid insert statement in mongodb? Select all valid.

• A. db.test.push({x:2,y:"apple"})
• B. db.test.insert«"x":2, "y":"apple"})
• C. db.test.insert({x:2,y:"apple"})
• D. db.test.insert({x:2},{y:"apple"})