Mongodb

MongoDB came to our campus for the SDE Intern hiring. The eligibility criteria were quite high, with the company mainly shortlisting students based on their academic profile and resumes. I was eligible and got shortlisted for the interview. There wasn't a separate coding OA for our drive. The first actual selection stage was the technical interview. Technical Interview The interview started with a short introduction and then the interviewer went directly into DSA. I was given a coding problem that looked fairly simple initially. I started explaining the brute-force approach and then tried to work towards a more efficient solution. The interviewer wasn't just interested in whether I could eventually write the code. He kept asking why I was choosing a particular approach and what its time and space complexity would be. I got a little nervous during the problem and ended up making the solution more complicated than it needed to be. The interviewer gave me a couple of hints pointing towards a simpler observation, but I wasn't able to make the connection quickly enough. I eventually got part of the solution working, but I couldn't finish the optimized version cleanly. After the DSA discussion, we moved to my projects. The interviewer asked me to explain one of the projects from my resume in detail. We discussed the architecture, the technologies I had used and some of the decisions I had made while building it. There were follow-up questions about databases and how I would handle increasing traffic. I explained the basic approach I had used, but the interviewer also asked what I would change if the application had significantly more users. The discussion then moved to core CS fundamentals. There were questions from OOP, DBMS and Operating Systems. Some of the questions were straightforward, while others were more practical. For DBMS, we discussed things like transactions, indexing, normalization and SQL. There was also a discussion around SQL vs NoSQL and when I would choose one over the other. Since the company was MongoDB, the interviewer also asked some questions related to NoSQL databases and MongoDB. I was asked about document-based storage and indexing. I knew the basic concepts, but I realized that I hadn't prepared MongoDB itself as deeply as I should have. I could explain the general idea but struggled with a couple of follow-ups. The interviewer then returned to the DSA problem from earlier and asked whether I could improve my solution. I tried another approach, but I was already running short on time. I managed to explain the idea partially, but I wasn't able to produce a completely working optimized solution. Result After the interview, I waited for the final update. Unfortunately, I wasn't selected for the MongoDB SDE Intern role. The rejection was a little frustrating because the DSA problem itself wasn't something extremely advanced. I think the main issue was that I panicked and overcomplicated the problem instead of stepping back and looking for the simpler observation. The experience was still useful because it showed me that interview preparation isn't just about solving hundreds of questions. I also need to be comfortable thinking out loud, handling hints and simplifying a problem when my first approach isn't working. The project discussion was another important takeaway. The interviewer went beyond the usual “explain your project” question and asked why I made certain choices and how I would scale the system. And for MongoDB specifically, I would definitely revise DBMS, SQL, NoSQL concepts, indexing and MongoDB fundamentals along with DSA. Overall, the interview was challenging but fair. I didn't make it through this time, but it gave me a much clearer idea of the areas I need to improve before the next SDE internship interview.