Question

_______ filters the document stream to allow only matching documents to pass unmodified into the next pipeline stage.

(a) $regex

(b) $reg

(c) $match

(d) None of the mentioned

This question was addressed to me during an online interview.

This question is from Aggregation Operations in division Aggregation Concepts and Aggregation Mechanics of MongoDB

Answer 1

Right answer is (c) $match

To explain: $match uses standard MongoDB queries. For each input document, outputs either one document (a match) or zero documents (no match).