MongoDB Questions and Answers – Aggregation Mechanics

This set of MongoDB Multiple Choice Questions & Answers (MCQs) focuses on “Aggregation Mechanics”.

1. Which of the following stages cannot appear multiple times in a pipeline?
a) $regex
b) $reg
c) $match
d) $out
View Answer

2. Point out the correct statement.
a) To access variables in expressions, use a string that prefixes the variable name with $$$
b) Expressions can include field paths and system variables, literals, expression objects, and expression operators
c) To specify a field path, use a string that prefixes with a dollar sign % the field name or the dotted field name
d) All of the mentioned
View Answer

3. Aggregation expressions use ______ path to access fields in the input documents.
a) mpath
b) dbpath
c) lpath
d) field
View Answer

4. Which of the following statement is equivalent to “$$CURRENT.<field>”?
a) “$%<field>”
b) “%<field>”
c) “$$<field>”
d) “$<field>”
View Answer

5. Point out the wrong statement.
a) Literals can be of any type
b) CURRENT cannot be rebound
c) MongoDB parses string literals that start with a dollar sign $
d) None of the mentioned
View Answer

6. ______ binds variables for use in the specified expression.
a) $skip
b) $let
c) $bind
d) None of the mentioned
View Answer

7. ________ applies an expression to each item in an array and returns an array with the applied results.
a) $map
b) $geo
c) $geoRear
d) None of the mentioned
View Answer

8. In the vars assignment block, ________ refers to the value of an externally defined variable low.
a) “$$low”
b) “$$lowin”
c) “$$1”
d) None of the mentioned
View Answer

9. To avoid treating numeric or boolean literals as projection flags, use the _______ expression to wrap the numeric or boolean literals.
a) $literal
b) $bool
c) $unwin
d) None of the mentioned
View Answer

10. MongoDB treats the literals as projection flags, valid only in the _______ stage.
a) $project
b) $gmap
c) $match
d) None of the mentioned
View Answer

Sanfoundry Global Education & Learning Series – MongoDB.

Here’s the list of Best Books in MongoDB.