There were 4 interviewers in my panel: Krishna Reddy P. Sir (K), Sujit P. Gurjar Sir (S), Manish Shrivastava Sir (M) and Kannan Srinathan Sir (he managed to remain uninterested during the whole interview).
Interviewers started off by asking details about my B.Tech major project report. It was a project on AI, so (S) took the liberty to start off questioning me about the same. Two questions in the interview, (S) asked me if it was okay if I was questioned about the project, or shall I prefer being questioned on a subject of my liking, to which I replied with an Affirmative for the latter option.
The word DBMS somehow triggered (K) :P. He came into full action mode and started firing questions towards me:
(K): What is the 3-tier architecture, please explain.
Me: [I did].
(K): What is a foreign key?
Me: A set of attributes in a relation that refer to the primary key of some other relation.
(K): Then what is a primary key?
Me: A candidate key that is chosen at the implementation level to uniquely identify each tuple in the relation.
(K): Then what is a candidate key?
Me: Any minimal superkey is known as a candidate key.
[By now, the whole panel burst out laughing, except (K), who was in a more facepalm mode. I didn’t realize that by now, I had managed to answer 4 straight questions without even using a single concrete definition. Finally, to address my clueless face, (M) pointed out that they were looking for a definition without any recursive definitions 😛 (to which, I too had a laugh).]
Me: (Finally, after realizing my blunder) A superkey is any set of attributes which can uniquely identify each tuple in the relation.
[In this the whole panel gave satisfactory nods (and a sigh of relief :P)].
(S): What is your favorite data structure?
Me: Hash table
[Some questions on hash table were asked, I do not remember them exactly].
(K): Databases utilize B-Trees for indexing. I claim that hash tables are better than B-Trees for database purposes. Counter my argument.
Me: [I was clueless at the moment, and gave some wrong answers, which was soon countered by (S) and (M). I took a moment to ponder upon it, but wasn’t able to come up with an answer. (K) Soon decided to move ahead with the next question.
(K): Are you familiar with 2PL?
(K): Define it
Me: [I did].
(K): Why do we need 2PL, what’s wrong with 1PL? Give an example on the board.
Me: [I drew a schedule which was not serializable] 1PL allows the transactions to acquire locks even after releasing a lock, due to which schedules can become nonserializable, whereas this is not possible in 2PL, as a transaction in 2PL can not reacquire any lock once it has released any lock. [(K) Looked satisfied with this answer].
(M): That should be enough, you may go.
I remember (K) trick questioning me 2 or 3 times, but don’t really remember what they were. In total, the interview was quite chillaxed, with the interviewers helping me out, whenever I was stuck anywhere. They were having a nice laugh here and there, which also helped me reduce my anxiety.
The interview lasted 10-15 minutes. To my surprise, nobody inquired about:
- Why M.Tech?
- Why not M.S.?
- Why are you interested in pursuing M.Tech straight out of B.Tech?
Nothing. From the first question itself, they started testing my technical knowledge.