Suppose you want to join two collections in the same database. What aggregation stage do you need to use?

• A.$out
• B.$lookup
• C.$project

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Select all true statements about reconfiguring a replica set with rs.reconfig().

• A.When we reconfigure a replica set with rs.reconfig(), we don't need to restart any of the individual nodes.
• B.When we reconfigure a replica set with rs.reconfig(), we need to update all of the nodes' configuration files.

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You have the following index in a movies collection: { "title": 1, "imdb.rating": -1, "imdb.votes": -1, "type": 1 } Can the following query use the given index for both filtering and sorting?
db.movies.find( { "title": { "$lt": "M" } } ).sort( { "imdb.votes": -1 } )

• A.Yes
• B.No

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How to create a new user with the root role named root_user with password root123?

• A.use admin db.createUser({ user: "root_user", pwd: "root123", roles: ["dbAdmin"] })
• B.use admin db.createUser({ user: "root_user", pwd: "root123", roles: ["root"] })
• C.use admin db.createUser({ user: "root_user", pwd: "root123", roles: ["clusterAdmin"] })
• D.use admin db.createUser({ user: "root_user", pwd: "root123", roles: ["dbAdminAnyDatabase"] })

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Suppose you have an accounts collection in your database. Only the following documents are stored in this collection: { _id: ObjectId("61af47c6e29861661d063714"), account_id: 1010, type: 'investment', limit: 2000000 }, { _id: ObjectId("61af47c6e29861661d063715"), account_id: 4336, type: 'derivatives', limit: 100000 }, { _id: ObjectId("61af47c6e29861661d063716"), account_id: 4336, type: 'commodity', limit: 1000 }, { _id: ObjectId("61af47c6e29861661d067825"), account_id: 7355, type: 'commodity', limit: 500000 }, { _id: ObjectId("61b1bde1ceb6f770f56b0cd9"), account_id: 4915, type: 'investment', limit: 2000000 } How many documents will be returned in response to the following aggregation pipeline? [{ $group: { _id: "$type", number_of_accounts: { $sum: 1 } }}, { $match: { number_of_accounts: { $gt: 1 } }}]

• A.1
• B.0
• C.3
• D.2

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