MongoDB Junior Engineer: two array questions, an LRU Cache LLD and a sharding-heavy system design

I applied on LinkedIn and got a response from HR the next week. The process was fairly standard:

HR Phone Screen

Very relaxed 30-minute call discussing my background, why MongoDB and availability for the next rounds.

Technical Screen

It was an easy and medium LeetCode question. They were both array based so I would recommend studying them. I was asked Intersection of Two Arrays and Product of Array Except Self. I think if you've prepared, given there was no hard LeetCode question, you should be fine for time.

Virtual Onsite

1. LLD: LRU Cache which was fun to implement and the engineer I was paired with was very enthusiastic and clearly a very strong engineer so it was my favorite interview of the process.

2. System Design: They went deep on sharding and it felt very similar to designing a distributed key-value store. Pretty hard so it's worth spending some time practicing these questions.

3. Behavioural: The questions were typical and all covered in the behavioural playbook. I just followed the STAR process and I had no issues answering any of the questions (mainly about the biggest projects I had worked on in the past).

I got the call from the recruiter with the good news a few days later asking about compensation and start dates. Overall an enjoyable experience and passable if you study beforehand.