C100DBA Online Practice Questions and Answers

The following aggregation option is used to specify the specific fields that needs to be passed to the next stage of the aggregation pipeline:

A. $project

B. $aggregate

C. $match

D. $group

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 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 operator can be used to limit the number of documents in an array field of a document after an update is performed?

A. $arrayLimit

B. $push along with $each, $sort and $slice

C. $removeFromSet

D. None of the above

The oplog (operations log) is a special capped collection that keeps a rolling record of all operations that modify the data stored in your databases. All the replica set members contain a copy of the oplog in the following collection:

A. .oplog.rs

B. oplog.rs

C. ..oplog.rs

D. local.oplog.rs

Consider the following posts document:

Which of the following queries will return the documents but with only the first two tags in the tags array?

A. db.posts.find({author:"Tom"?limit({tags:2})

B. db.posts.find({author:"Tom"?limit($slice:{tags:>;)

C. Both "db.posts.find({author:"Tom"},{tags:{$slice:2}})" and "db.posts.find({author:"Tom"}).limit($slice: {tags:2})" are valid. $slice works both with projection and limit.

D. db.posts.find({author:"Tom">,{tags:{$slice:2?

Consider the following document from the products collection: What does the following query using $elemMatch return? db.products.find( { product_code: "345678" }, { variations: { $elemMatch: { size: ^L^ } } } )

A. Returns the complete document but retrieves only the size field from the array

B. Returns the document but with only one element in the variations array (corresponding to size L)

C. Returns the complete document since MongoDB does not support partial array retrieval

D. Returns the complete document but retrieves only the size field from the array and also with only one element in the variations array (corresponding to size L)

The________operator can be used to identify an element in the array to be updated without explicitly specifying the position of the element.

A. $ elemMatch

B. $slice

C. Updating an array field without knowing its index is not possible.

D. $

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

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