[Oct 13, 2021] C100DBA Ultimate Study Guide - Pass4guide
Ultimate Guide to Prepare C100DBA Certification Exam for MongoDB Certified DBA Associate in 2021
NEW QUESTION 45
You have the following index on the toys collection:
{
"manufacturer" : 1,
"name" : 1,
"date" : -1
}
Which of the following is able to use the index for the query? Check all that apply.
- A. db.toys.find( { date : "2015-03-01", manufacturer : "Loggo", name : "Brick Set" } )
- B. db.toys.find( { name : "Big Rig Truck", date : "2013-02-01", manufacturer : "Tanko"
- C. db.toys.find( { manufacturer : "Matteo", name : "Barbara", date : "2014-07-02" } )
Answer: A,B,C
NEW QUESTION 46
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. findQ and findOneQ returns cursors to the collection documents
- C. find.limit(l) is not the same query as findOne()
- D. findOneQ returns the actual first document retrieved from a collection
Answer: B
NEW QUESTION 47
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, b :1, c:l, d:l})
- C. db.test.ensurelndex( { a : 1, c: 1, d: 1, b : 1})
- D. CH db.test.ensurelndex( { a :1, c:l})
Answer: C,D
NEW QUESTION 48
What tool do you use if you want to extract a CSV from mongo?
Answer:
Explanation:
mongoexport
NEW QUESTION 49
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. B, C
- B. A, B
- C. A
- D. A, B, C
Answer: A
NEW QUESTION 50
Consider the following documents:
You perform the following query;
How many documents will be updated by the query?
- A. 0
- B. 1
- C. 2
- D. 3
- E. 4
Answer: C
NEW QUESTION 51
When should we consider representing a one-to-many relationship in an embedded collection instead of separate collection?
- A. Always
- B. When the many is not very large
- C. When the many is very large
- D. Never
Answer: B
NEW QUESTION 52
Which command can be used to rebuild the indexes on a collection in MongoDB?
- A. db.collection.reIndex({author:l})
- B. db.collection.createlndex({relndex:l})
- C. db.collection.createIndex({author:l}).reIndex()
- D. db.collection.relndexQ
Answer: D
NEW QUESTION 53
What is the equivalent command in MongoDB for the following SQL query?
SELECT * FROM posts WHERE author like "%john%"
- A. db.posts.find( { author: /John/ } )
- B. db.posts.find( { $like: {author: /John/} } )
- C. db.posts.find( { author: {$like: /John/} } )
- D. db.posts.find( { author: /AjohnA/ > )
Answer: A
NEW QUESTION 54
Aggregation Pipelines have a limit of:
- A. 16 MB document and 100 MB RAM
- B. No limit on document and 100 MB RAM
- C. 2 MB document and 100 MB RAM
- D. 2 MB document and no limit on RAM
Answer: A
NEW QUESTION 55
By default, the MongoDB cursor in mongo shell is configured to return how many documents? To get the next set of documents, which command is used?
- A. 20, it
- B. 50, it
- C. 200, more
- D. No limit, none
Answer: A
NEW QUESTION 56
Consider that our posts collection contains an array field called tags that contains tags that the user enters. {
Which of the following commands will find all the posts that have been tagged as tutorial.
- A. db.posts.find( { tags : "tutorial" } );
- B. db.posts.find( { tags : ["tutorial"] } );
- C. db.posts.findInArray( { tags : "tutorial" > );
- D. db.posts.find( { $array : {tags: "tutorial") > );
Answer: A
NEW QUESTION 57
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
Answer: A
NEW QUESTION 58
Which of the following is true about sharding?
- A. Creating a sharded key automatically creates an index on the collection using that key
- B. A sharded environment does not support sorting functionality since the documents lie on various mongod instances
- C. Sharding is enabled at the database level
- D. We cannot change a shard key directly/automatically once it is set up
Answer: D
NEW QUESTION 59
Which format/standard is used by MongoDB internally to store documents?
- A. JSON
- B. B+ Trees
- C. BSON
- D. JSON - Extended
Answer: A
NEW QUESTION 60
The difference between $push and $addToSet is:
- A. $addToSet adds the item to the field only if it does not exist already; while $push pushes the item to the field irrespective of whether it was present or not
- B. $addToSet adds the item to the field only if the new item is of the same datatype
- C. There is no major difference between them. $addToSet is a deprecated version of $push.
- D. $addToSet needs the fields to be already present while $push will work even if the field is not present
Answer: A
NEW QUESTION 61
Given a collection posts as shown below having a document array comments, which of the following command will create an index on the comment author descending?
- A. db.posts.createIndex({comments.$.author": {$desc:l>});
- B. db.posts.createIndex({comments.author":-l});
- C. db.posts.createIndex({commerits.$.author":-l});
Answer: B
NEW QUESTION 62
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( [{ $group: { _id: { state: Estate", city: "$city" },pop: { $sum: 1 > > >] )
- C. db.population.aggregate( [{ $group: { _id: { state: Estate", city: "$city" },pop: { $sum: "$pop" } } }] )
- D. db.population.aggregate( [{ $group: { _id: { city: "$city" },pop: { $sum: "$pop" } } }] )Multi Document Transaction is not supported by MongoDB
Answer: C
NEW QUESTION 63
Which of the following is true about aggregation framework?
- A. A single aggregation framework operator can be used more than once in a query
- B. the aggregate command operates on a multiple collection
- C. Pipeline expressions are stateless except accumulator expressions used with $group operator
- D. Each aggregation operator need to return atleast one of more documents as a result
Answer: A,C,D
NEW QUESTION 64
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