Dumb interviewer does not understand basic concepts of Kafka and was trying to act smart like she is asking real good question. Trust me i could have made a fresher understand concepts of kafka instead of her. After some dumb, pointless questions in kafka we moved to HLD of coupon service where I was asked to design it. I picked MongoDB as solution to which she said how would you handle during sale if you want to give a particular coupon only 100 times to total users. I said we can do locking,synchronizing,virtual keyword etc. But she wanted to hear something specific which she made up in her mind that is best. Then I said keep it in redis and it is distributed you dont have to use consul etc for consistency between different nodes. Still she was crying out consistency consistency then I figured out she wanted me to implement Relational DB so i told her that we should take DB as any relational DB. She did not followup but I am sure any good interviewer would have complained about scale in this as there might be millions of coupons created every week and millions of hits to apply coupon how would you scale relational but as I said dumb interviewer with preset in mind what to hear from candidate or may be implemented only that.
