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Given a cursor named myCursor, which command returns a boolean value?:

myCursor.find()

myCursor.hasNext()

myCursor.sort()

myCursor.next()

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What happens when an index is created in MongoDB?

The indexed fields are encrypted for security.

The indexed fields are compressed to reduce storage space.

Data structures are created to improve query performance on the indexed fields.

The indexed fields are sorted in descending order.

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How do you find documents with a matching item in an embedded array?:

db.customers.findmatch ({"jobs":"secretary"})

db.customers.find ({"jobs:secretary"})

db.customers.find ({"jobs":"secretary"})

db.customers.find ({"jobs":["secretary"]})

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What is the maximum number of array fields per multikey index? (Select one.)

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What is a compound index? (Select one.)

An index that contains references to multiple fields within a document

An index that supports queries that are run on two collections at the same time

An index that supports queries that combine the field name and the value into one string

An index that supports queries against unknown or arbitrary fields

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In the MongoDB shell, how can you tell if an index was used with a query?:

db.customers.find({lastName: 'smith'}).explain()

db.customers.find({lastName: 'smith'}).usedIndex()

db.customers.find({lastName: 'smith'}).perf()

db.customers.find({lastName: 'smith'}).plan()

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What is the purpose of the $match stage in MongoDB aggregation framework?

To group data based on a specified expression

To filter documents based on a specified condition

To rearrange documents based on a specified expression

To summarize data from multiple documents

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How can you update an array field by adding elements to it in MongoDB?

Using the $unset operator with the added elements.

Using the $addToSet operator with the new elements.

Using the $push operator with the new elements.

Using the $set operator with the entire updated array.

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Given a cursor named myCursor, pointing to the customers collection, how to you get basic info about it?:

myCursor.dump()

myCursor.stats()

myCursor.info()

myCursor.explain()

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What is the purpose of the $unwind stage in MongoDB aggregation framework?

To join data from multiple collections

To convert data into a graph

To store data in a flat file

To decompose an array into separate documents

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