MongoDB C100DBA Online Practice Questions and Exam Preparation

MongoDB C100DBA Online Questions & Answers

• Question 21:

  Which type of indexes does MongoDB support?

  A. All of the above
  B. Compound Indexes
  C. Multikey Indexes
  D. Geospatial Indexes
  A. All of the above

• Question 22:

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

  A. findQ returns all the documents in a collection while findOne() retrieves only the first one.
  B. find.limit(l) is not the same query as findOne()
  C. findOneQ returns the actual first document retrieved from a collection
  D. findQ and findOneQ returns cursors to the collection documents
  D. findQ and findOneQ returns cursors to the collection documents

• Question 23:

  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?

  A. db.population.aggregate( [{ $group: { _id: { state: "$state", city; "$city" },pop: { $sum: 1 > > >] )
  B. db.population.aggregate( [{ $group: { _id: { state: Estate", city: "$city" },pop: { $pop: 1 } } }] )
  C. db.population.aggregate( [{ $group: { _id: { state: Estate", city: n$city" },pop: { $sum: "$pop" } } }] )
  D. db.population.aggregate( [{ $group: { _id: { city: "$city" },pop: { $sum: "$pop" } } }] )Multi Document Transaction is not supported by MongoDB
  C. db.population.aggregate( [{ $group: { _id: { state: Estate", city: n$city" },pop: { $sum: "$pop" } } }] )

• Question 24:

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

  A. mongofile
  A. mongofile

• Question 25:

  In which of the following scenarios is sharding not the correct option. Select all that apply.

  A. The write operations on the collection are low
  B. The write operations on the collection are very high
  C. The working set in the collection is expected to grow very large in size
  D. The collection is a read intensive collection with less working set
  A. The write operations on the collection are low
  D. The collection is a read intensive collection with less working set

• Question 26:

  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?

  A. db.population.aggregate( [{ $group: { _id: { state: "$state", city: "$city" },pop: { $pop: 1 } } }] )
  B. db.population.aggregate( [{ $group: { _id: { city: "$city" },pop: { $sum: "$pop" } } }] )Multi Document Transaction is not supported by MongoDB
  C. db.population.aggregate( [{ $group: { _id: { state: Estate", city: "$city" },pop: { $sum: "$pop" } } }] )
  D. db.population.aggregate( [{ $group: { _id: { state: Estate", city: "$city" },pop: { $sum: 1 > > >] )
  C. db.population.aggregate( [{ $group: { _id: { state: Estate", city: "$city" },pop: { $sum: "$pop" } } }] )

• Question 27:

  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
  D. 7
  B. 2

• Question 28:

  What does the totalKeysExamined field returned by the explain method indicate?

  A. Number of documents that match the query condition
  B. Number of index entries scanned
  C. Details the completed execution of the winning plan as a tree of stages
  D. Number of documents scanned
  B. Number of index entries scanned

• Question 29:

  Which of the following node is used during election in a replication cluster?

  A. primary
  B. arbiter
  C. hidden
  D. secondary
  B. arbiter

• Question 30:

  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 ] > )
  A. db.c.find( { > , { b : { $slice : [ 0 , 5 ] } } )