2021 Valid C100DBA Exam Updates - 2021 Study Guide
C100DBA Certification - The Ultimate Guide [Updated 2021]
NEW QUESTION 68
You have designed a web application with mongoDB. You have configured replication. The replica set is in place and function properly. What happens in case of failure?
- A. Failover happens automatically
- B. Switchover happens automatically
- C. Switchover needs to be done manually
- D. Failover needs to be done manually
Answer: A
NEW QUESTION 69
Consider a collection posts which has fields: Jd, post_text, post_author, post_timestamp, post_tags etc. Which of the following query retrieves ONLY the key named post_text from the first document retrieved?
- A. db.posts.find({},{_id:Of post_text:1})
- B. db.posts.findOne({post_text: 1})
- C. db.posts.finOne{},{post_text:l})
- D. db.posts.finOne({},{_id:0, post_text:1})
Answer: D
NEW QUESTION 70
Which node in a replica set does accept write operation?
- A. arbiter
- B. primary
- C. secondary
- D. hidden
Answer: B
NEW QUESTION 71
Which of the following is a valid Replica Set configuration if you want:
1-Have 3 copies of everything
2- That RS3 is never primary
2- That RSI and RS2 can be primary?
You had to see the different configurations, RS3 could be hidden or priority 0 (But not a referee because we need
3 replicas), while RSI and RS2 could NOT have priority 0 or be hidden or anything like that In a 4-member RS RSO , RSI, RS2 and RS3 + Referee, RSO (primary) falls after some write operations that have replicated RSI and RS2 (but NOT RS3), who can get up as the new primary?
The configuration comes and in it we see that RS2 has a hidden: true (or a priority: 0, (I don't remember)
- A. ORS2
- B. O arbiter
- C. ORS3
- D. ORS1
- E. RSO
Answer: D
NEW QUESTION 72
Which option can be used with update command so that a new document gets created if no matching document is found based on the query condition?
- A. {update: true, insert: true} as the third parameter of update command
- B. Specify {upsert : true } as the third parameter of update command
- C. upsert command instead of update command
- D. This has to be handled in application code (Node.js, PHP, JAVA, C#, etc.) and cannot be handled in mongo shell query
Answer: B
NEW QUESTION 73
Consider the following example document from the sample collection. All documents in this collection have the same schema.
Which of the following queries will replace this with the document.
- A. db.sample.update( { "_id" : 3 > , { "_id" : 7 , "c" : 4 > )
- B. db.sample.update( { "_id" : 3 > , { "_id" : 7 , "c" : 4 > , { "justOne" : true > ) / This operation cannot be done with a single query.
- C. db.sample.update( { "_id" : 3 > , { "_id" : 7 , "c" : 4 , { "$unset" : [ "a" , "b" ] } } )
- D. db.sample.update( { "_id" : 3 } , { "$set" : { "_id" : 7 , "c" : 4 > > )
Answer: C
NEW QUESTION 74
Consider the following example document:
{
"_id": Objectld("5360c0a0a655a60674680bbe"),
"user"
"login": "irOn"
"description": "Made of steel"
"date": ISODate("2014-04-30T09:16:45.836Z"),
}
>
and index creation command:
db.users.createlndex( { "user.login": 1, "user.date": -1 }, "mylndex" ) When performing the following query:
db.users.find( { "user.login": /Air.*/ },
{ "user":1, "_id":0 > ).sort( { "user.date":1 > )
which of the following statements correctly describe how MongoDB will handle the query? Check all that apply.
- A. As an indexed query using "mylndex" because field "user.login" is indexed
- B. None of the above
- C. As an optimized sort query (scanAndOrder = false) using "mylndex" because we are sorting on an indexed field
- D. MongoDB will need to do a table/collection scan to find matching documents
- E. As a covered query using "mylndex" because we are filtering out "_id" and only returning "user.login"
Answer: A
NEW QUESTION 75
Which of the following commands can cause the database to be locked?
- A. All of the above
- B. Map-reduce
- C. Issuing a query
- D. Inserting data
Answer: A
NEW QUESTION 76
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. Sharding is enabled at the database level
- D. A sharded environment does not support sorting functionality since the documents lie on various mongod instances
Answer: B
NEW QUESTION 77
Which of the following does MongoDB use to provide High Availability and fault tolerance?
- A. Sharding
- B. Replication
- C. Indexing
- D. Write Concern
Answer: B
NEW QUESTION 78
Dada una coleccion, cuales devuelve con la siguiente query
db.coleccion.find({nombre:"ruben",apellido:"gomez"},{nombre:l,apellido:l,aficion:l});
- A. { "-id" : Objectld("580a42b5dfblb5al7427d302"), "nombre" : "ruben", "apellido" : "gomez", "aficion" :
v u "flipar" } - B. { "_id" : Objectld("580a42acdfblb5al7427d301"), "nombre" : "ruben", "apellido" : "Pablo" , "aficion" : u
"flipar"} - C. { "_id" : Objectld("580a42acdfblb5al7427d301"), "nombre" : "Luis", "apellido" : "gomez", "aficion" : u
"flipar" } - D. { "_id" : Objectld("580a42acdfblb5al7427d301"), "nombre" : "ruben", "apellido" : "gomez" >
Answer: A,D
NEW QUESTION 79
Which mongodb tool is used to report details on number of database operations in MongoDB?
- A. mongodump
- B. mongorestore
- C. mongostat
- D. mongotop
Answer: C
NEW QUESTION 80
Aggregation Pipelines have a limit of:
- A. No limit on document and 100 MB RAM
- B. 16 MB document and 100 MB RAM
- C. 2 MB document and 100 MB RAM
- D. 2 MB document and no limit on RAM
Answer: B
NEW QUESTION 81
Which operations add new documents to a collection?
- A. update
- B. delete
- C. insert
- D. Create
Answer: C,D
NEW QUESTION 82
What is the output of the following program?
- A. 60 s
- B. 100 ms
- C. 1s
- D. 100 s
Answer: A
NEW QUESTION 83
Below is a sample document in a given collection test.
{ a : 5, b : 3, c: 2, d : 1 >
Given a compound index { a: 1, b:l, c:l, d:l}, Which of the below query will not use in-memory sorting? Select all valid.
- A. db.test.find( { a: 5, b: 3 } ).sort( { c: 1, d : 1 } )
- B. db.test.find( { a: 5, b: 3 } ).sort( {c: 1 } )
- C. db.test.find( { a: 5, b: 3 } ).sort( { a: 1} )
- D. db.test.find( { a: 5, b: 3 } ).sort( { a: 1, b: 1, c: 1 > )
Answer: A,B
NEW QUESTION 84
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