Aggregation Concepts And Mechanics(Engineering > Computer Science And Engineering > Mongodb ) Questions and Answers
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Answer: Option B. -> $last $last has the following syntax: { $last: }.
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Answer: Option D. -> None of the mentioned The Boolean expression evaluates all other values as true, including non-zero numeric values and arrays.
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Answer: Option C. -> DESCENDING is one of the allowed results of a $let expression However, since $ is equivalent to $$CURRENT., rebinding CURRENT changes the meaning of $ accesses.
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Answer: Option D. -> None of the mentioned $let defines variables for use within the scope of a subexpression and returns the result of the subexpression.
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Answer: Option B. -> $limit groups output documents by a specified operator $group consumes all input documents and outputs one document per each distinct group.
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Answer: Option D. -> None of the mentioned If low is not defined outside this $let expression block, the expression is invalid.
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Answer: Option A. -> it The mongo shell iterates the returned cursor automatically to print the results.
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Answer: Option B. -> filters Other pipeline operations provide tools for grouping and sorting documents by specific field.
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Answer: Option A. -> finalize Finalize fucntion is optional for mapreduce operation.
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Answer: Option D. -> None of the mentioned $let defines variables for use within the scope of a subexpression and returns the result of the subexpression.