C100DBA Online Practice Questions and Answers

The MongoDB explain() method does not support which of the following verbosity mode:

A. executionStats

B. queryPlanner

C. customExecutionStats

D. allPlansExecution

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. 7

B. 2

C. 1

D. 0

Which of the documents below will be retrieved by the following query? Assume the documents are stored in a collection called "sample". Check all that apply.

db.sample.find( { "$or" : [ { "a" : { "$in" : [ 3, 10] > }, { "b" : { "$lt" : 2 > > ] > )

A. {''__id" :3, "a": 4, "c" :0, "b" :14}

B. {''_Jd" :7, "a": 8, "c" :1, "b" :7}

C. {".Jd" :6, "a": 1, "c" :1, "b" :5}

D. { ''\Jd" :9, "a": 17, "c": 1, "b": 1}

E. { \Jd" :10,"a": 3, "c": 1, "b": 1}

F. {".Jd" :: 2, "a": 2, "c" :: 0, "b": 1}

G. {".Jd" :: 4, "a": 5, "c" :: 0, "b": 17}

H. {".Jd" :: 1, "a": 0, "c" :: 0, "b": 2}

I. {".Jd" :: 5, "a": 3, "c" :: 0, "b": 12}

J. {".Jd" :: 8, "a": 11, "c": 1, "b": 0}

Which of the following aggregation commands in MongoDB does not support sharded collections?

A. mapReduce

B. group

C. aggregate

D. All of the above

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})

Consider that the posts collection contains an array called ratings which contains ratings given to the post by various users in the following format:

Which of the following query will return all the documents where the ratings array contains elements that in some combination satisfy the query conditions?

A. db.inventory.find( { ratings: { $elemMatch: { $gte: 3, $lte: 6 } } } )

B. db.inventory.find( { ratings: { $elemMatch: { $gt: 3, $lt: 6 }

C. db.inventory.find( { ratings: { ratings.$: { $gt: 5, $lt: 9 } } } )

D. db.inventory.find( { ratings: { ratings: { $gt: 5, $lt: 9 } } } )

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

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

Which of the following does MongoDB use to provide High Scalability?

A. Replication

B. Write Concern

C. Indexing D. Sharding

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

A. All of the above

B. Inserting data

C. Map-reduce

D. Issuing a query