MongoDB Questions and Answers – Pipeline and Sharded Collections

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This set of MongoDB Multiple Choice Questions & Answers (MCQs) focuses on “Pipeline and Sharded Collections”.

1. Which of the following returns a substring of a string?
a) $subs
b) $substring
c) $substr
d) None of the mentioned
View Answer

Answer: c
Explanation: $substr accepts three expressions as arguments: the first argument must resolve to a string, and the second and third arguments must resolve to integers.

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2. Point out the correct statement.
a) $substr ends at a specified index position up to a specified length
b) $toLower converts a string to lowercase
c) $gtle returns true if the first value is greater than or equal to the second
d) All of the mentioned
View Answer

Answer: b
Explanation: If the argument resolves to null, $toLower returns an empty string “”.

3. Which of the following accepts a single argument expression?
a) $toLow
b) $toUpper
c) $toEqual
d) None of the mentioned
View Answer

Answer: b
Explanation: $toUpper converts a string to uppercase.

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4. Which of the following performs case-insensitive string comparison?
a) $strcasecmpequals
b) $strcasecmp
c) $strcmp
d) None of the mentioned
View Answer

Answer: a
Explanation: $strcasecmp returns 0 if two strings are equivalent.

5. Point out the wrong statement.
a) { $meta: “textScore” } expression is only meaningful in a pipeline that includes a $match stage with a $text query
b) The { $meta: “textScore” } expression is the only expression that the $sort stage accepts
c) $toLower only has a well-defined behavior for strings of ASCII characters
d) None of the mentioned
View Answer

Answer: d
Explanation: A $meta expression has the following syntax:{ $meta: <metaDataKeyword> }.

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6. _______ is used for access text search metadata.
a) $text
b) $metades
c) $meta
d) All of the mentioned
View Answer

Answer: c
Explanation: $meta returns the metadata associated with a document in a pipeline operations.

7. Which of the following accepts named parameters?
a) $reduce
b) $letnum
c) $let
d) None of the mentioned
View Answer

Answer: d
Explanation: $let defines variables for use within the scope of a subexpression and returns the result of the subexpression.

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8. _______ returns the number of elements in the array.
a) $number
b) $size
c) $div
d) None of the mentioned
View Answer

Answer: b
Explanation: The argument for $size can be any expression as long as it resolves to an array.

9. _________ returns a value without parsing.
a) $string
b) $literal
c) $characters
d) None of the mentioned
View Answer

Answer: b
Explanation: Use for values that the aggregation pipeline may interpret as an expression.

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10. db.collection.aggregate() returns a _______ and can return result sets of any size.
a) replica
b) cursor
c) document
d) $subtract
View Answer

Answer: b
Explanation: The aggregate command can return results as a cursor or store the results in a collection, which are not subject to the size limit.

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Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn | Youtube | Instagram | Facebook | Twitter