15 to 30 random questions in 15 to 30 minutes, by the level you choose: crud, queries, indexes, aggregation, modelling, replication, sharding. After you submit you get your score, your strong and weak topics, and the right answer with an explanation for every question.
Want to revise first? Read the MongoDB interview questions and answers.
The test covers 14 topics across three levels. Each attempt picks 15 to 30 questions at random, by the level you choose, so every attempt is different.
One question from each level, the way they appear in the test. A new set comes on the 1st of every month. Try it, then open the answer.
Answer: countDocuments(). db.orders.countDocuments({ city: "Jaipur" }) counts the matching documents on the server and returns a number. estimatedDocumentCount() is faster but takes no filter, because it reads the collection metadata.
Answer: The extended reference pattern. An extended reference stores the id plus the few fields most often needed, so showing an order needs no $lookup. The copied fields should be ones that rarely change, or where the value at order time is the correct one.
db.items.insertOne({ _id: 1, price: 200 })
db.items.updateOne(
{ _id: 1 },
{ $mul: { price: 1.5, discount: 2 } }
)Answer: price: 300, discount: 0. $mul multiplies existing numbers, so price becomes 300. For a missing field it does not use the multiplier as the value: it creates the field with 0 (of the multiplier's numeric type). $inc would have set discount to 2.
Take the full MongoDB mock test: 15 to 30 questions and 15 to 30 minutes, by level.
A question counts as right only when you pick exactly the right option, or all the right options where it says so; a question left blank counts as wrong. Your score is the share of the test's questions you got right (15 to 30, by level). The result also scores every topic, so you know what to revise before the interview.
Yes. The MongoDB mock test is free. You need a free CoreHRx Jobs account to start it, so your score and the topics to work on are saved.
It depends on the level: Fresher has 15 questions in 15 minutes, Intermediate has 20 questions in 20 minutes, Experienced has 30 questions in 30 minutes. They are multiple-choice questions picked at random from a larger bank of MongoDB questions at your level, so every attempt is different.
The questions cover Aggregation Pipeline, Indexes, Query and Projection, Data Modelling, CRUD Operations, Update Operators, Explain and Performance, Replica Sets, Documents and BSON, Sharding, Transactions, Schema Validation, Read and Write Concerns, SQL vs NoSQL. Your result shows how you did in each topic.
Fresher if you are a student or have less than a year of experience, Intermediate for 1 to 5 years at work, and Experienced for 5 years or more.
Only your best MongoDB score, and only when it is 60% or more. It shows on the job applications you send on CoreHRx. Lower scores stay private.
Yes, up to 10 tests a day. Each attempt picks questions you have not seen recently first.