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)

In a sharded replica set environment, the w Option provides ability for write concern and j Option provides

ability for the data to be written on disk journal. Consider that we have a seven member replica set and we

want to assure that the writes are committed to journal.

What should be the value of j?

A. 1

B. 2

C. 0

D. 7

Which of the following is true about sharding?

A. Creating a sharded key automatically creates an index on the collection using that key

B. We cannot change a shard key directly/automatically once it is set up

C. A sharded environment does not support sorting functionality since the documents lie on various mongod instances

D. Sharding is enabled at the database level

Which command can be used to rebuild the indexes on a collection in MongoDB?

A. db.collection.createlndex({relndex:l})

B. db.collection.reIndex({author:l})

C. db.collection.relndexQ

D. db.collection.createIndex({author:l}).reIndex()

In a replicated cluster, which of the following node would only be used during an election?

A. arbiter

B. primary

C. hidden

D. secondary

If you have created a compound index on (A,B, C) which of the following access pattern will not be able to utilize the index?

A. A, B, C

B. A

C. B, C

D. A, B

Which is the correct order (lowest to highest) in which MongoDB compares the BSON types?

A. Number, Null, String and Object

B. Null, Number, Object and String

C. Null, Number, String and Object

D. String, Null, Number and Object

Which of the following operator can be used to control the number of items of an array that a query returns?

A. $ elemMatch

B. $slice

C. $

D. MongoDB does not support partial retrieval of items from an array

Which of the following index would be optimum for the query?

Select all valid. db.test.find( { a : 5, c : 2 }) A. db.test.ensurelndex( { c:l, a: 1})

B. db.test.ensurelndex( { a : 1, c: 1, d: 1, b : 1})

C. CH db.test.ensurelndex( { a :1, c:l})

D. db.test.ensurelndex( { a: 1, b :1, c:l, d:l})

What is the maximum size of Index Key Limit and Number of Indexes per collection?

A. 1024 bytes and 64 indexes

B. 12 mega bytes and 64 indexes

C. 64 bytes and 1024 indexes

D. 1024 bytes and unlimited indexes