Verified C100DBA exam dumps Q&As with Correct 123 Questions and Answers [Q71-Q86]

Q71. Which option should be used to update all the documents with the specified condition in the MongoDB query?

specify {all: true} as the third parameter of update command

updateAII instead of update

specify {updateAII: true} as the third parameter of update command

specify {multi : true} as the third parameter of update command

Q72. You have a replicated cluster with 1 primary, 3 secondary, 1 arbiter. One of the secondary is hidden. What is the replication factor of this replicated cluster?

Q73. What does the totalKeysExamined field returned by the explain method indicate?

Number of documents that match the query condition

Number of index entries scanned

Details the completed execution of the winning plan as a tree of stages

Number of documents scanned

Q74. What does the following $slice query return using the following command? db.posts.find( {}, { comments: {
$slice: [ -10, 5 ] } } )

Returns 5 comments, beginning with the last 10 items

Returns 10 comments, beginning with the last

Returns 10 comments, beginning with the first

Returns 5 comments, beginning with the first 10 items

Q75. The difference between $push and $addToSet is:

$addToSet needs the fields to be already present while $push will work even if the field is not present

$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

$addToSet adds the item to the field only if the new item is of the same datatype

There is no major difference between them. $addToSet is a deprecated version of $push.

Q76. Which is the default mode in which the explain() command runs?

allPlansExecution

customExecutionStats

queryPlanner

executionStats

Q77. What is the equivalent command in MongoDB for the following SQL query?
SELECT * FROM posts WHERE author like “%john%”

db.posts.find( { author: /John/ } )

db.posts.find( { author: /AjohnA/ > )

db.posts.find( { $like: {author: /John/} } )

db.posts.find( { author: {$like: /John/} } )

Q78. What tool do you use to see if you have a problem in the consumption of disk I / 0?

Q79. Aggregation Pipelines have a limit of:

No limit on document and 100 MB RAM

2 MB document and no limit on RAM

2 MB document and 100 MB RAM

16 MB document and 100 MB RAM

Q80. In order to ensure that you can maintain high availability in the face of server failure, you should implement which of the following?

Sharding

Properly defined user roles

Replication

Put indexes on all of your documents

The proper storage engine

Q81. 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.

db.toys.find( { name : “Big Rig Truck”, date : “2013-02-01”, manufacturer : “Tanko”

db.toys.find( { manufacturer : “Matteo”, name : “Barbara”, date : “2014-07-02” } )

db.toys.find( { date : “2015-03-01”, manufacturer : “Loggo”, name : “Brick Set” } )

Q82. The________operator can be used to identify an element in the array to be updated without explicitly specifying the position of the element.

$ elemMatch

$slice

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

Q83. Dada una coleccion, cuales devuelve con la siguiente query
db.coleccion.find({nombre:”ruben”,apellido:”gomez”},{nombre:l,apellido:l,aficion:l});

{ “-id” : Objectld(“580a42b5dfblb5al7427d302”), “nombre” : “ruben”, “apellido” : “gomez”, “aficion” :
v u “flipar” }

{ “_id” : Objectld(“580a42acdfblb5al7427d301”), “nombre” : “Luis”, “apellido” : “gomez”, “aficion” : u
“flipar” }

{ “_id” : Objectld(“580a42acdfblb5al7427d301”), “nombre” : “ruben”, “apellido” : “Pablo” , “aficion” : u
“flipar”}

{ “_id” : Objectld(“580a42acdfblb5al7427d301”), “nombre” : “ruben”, “apellido” : “gomez” >

Q84. Using an arbiter allows one to easily ensure an odd number of voters in replica sets. Why is this important?

To help in disaster recovery

To protect agains network partitions

To enable certain read preference settings

To add greather redundancy

For more efficient backup operations

Q85. Below is a sample document of “orders” collection

Q86. 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^ } } } )

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

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

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

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)