MongoDB Online Quiz

Q 1 - Which of the following is correct about MongoDB?

A - MongoDB uses JSON format to represent documents

B - MongoDB supports collection joins

C - MongoDB supports some of the SQL functions

D - MongoDB supports geospatial indexes

Q 2 - Which of the following commands finds all the documents in the posts collection with post timestamp field as null?

A - db.posts.find( { post_timestamp : { $type: 10 } } )

B - db.posts.find( { post_timestamp: { $type: null } } )

C - db.posts.find( { post_timestamp: { $fieldtype: 10 } } )

D - db.posts.find( { post_timestamp: { $fieldtype: null } } )

Q 3 - In our posts collection, which command can be used to find all the posts whose author names begin lie between “A” and “C” in dictionary order?

A - db.posts.find( { post_author : { $gte : "A" , $lte : "C" } } );

B - db.posts.find( { post_author : { $gte : "C" , $lte : "A" } } );

C - db.posts.find( { post_author : { $gt : "A" , $lt : "C" } } );

D - This type of search is not supported by MongoDB. $lt and $gt operators are applicable only for numeric values.

Q 4 - Which option should be used to update all the documents with the specified condition in the MongoDB query?

A - updateAll instead of update

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

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

D - specify {updateAll: true} as the third parameter of update command

Q 5 - You can implement a multi-document transaction in MongoDB using which of the following concept?

A - Tailable Cursor

B - Two Phase Commits

C - Compound Indexing

D - Multi Document Transaction is not supported by MongoDB

Q 6 - 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( { author: {$like: /john/} } )

C - db.posts.find( { $like: {author: /john/} } )

D - db.posts.find( { author: /^john^/ } )

Q 7 - 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: { $sum: "$pop" } } }] )

B - db.population.aggregate( [{ $group: { _id: { state: "$state", city: "$city" },pop: { $sum: 1 } } }] )

C - db.population.aggregate( [{ $group: { _id: { state: "$state", city: "$city" },pop: { “$pop”: 1 } } }] )

D - db.population.aggregate( [{ $group: { _id: { city: "$city" },pop: { $sum: "$pop" } } }] )Multi Document Transaction is not supported by MongoDB

Q 8 - What will be the equivalent MongoDB command for the following SQL command:

SELECT author, count(*) FROM posts GROUP BY author HAVING count(*) > 1

A

db.posts.aggregate( [
   {
     $group: {
        _id: "$author",
        count: { $sum: 1 },
		$match: { count: { $gt: 1 } }
     }
   }
] )

B -

db.posts.aggregate( [
   {
     $group: {
        _id: "$author",
        count: { $sum: 1 }
     }
   },
   { $match: { count: { $gt: 1 } } }
] )

C -

db.posts.aggregate( [
   { $match: { count: { $gt: 1 } } },
   {
     $group: {
        _id: "$author",
        count: { $sum: 1 }
     }
   }
] )

D -

db.posts.aggregate( [
   {
     $group: {
        _id: "$author",
        count: { $sum: "$author" }
     }
   },
   { $match: { count: { $gt: 1 } } }
] )

Q 9 - In a sharded replica set environment, w defines the level and kind of write concern. Which of the following values of w specifies to return success only after a majority of voting members have acknowledged?

A - n

B - majority

C - m

D - major

Q 10 - What does the following $slice query return using the following command?

   
db.posts.find( {}, { comments: { $slice: [ -10, 5 ] } } )

A - Returns 5 comments, beginning with the last 10 items

B - Returns 10 comments, beginning with the first

C - Returns 10 comments, beginning with the last

D - Returns 5 comments, beginning with the first 10 items