Meta Data Scientist interview questions

First quick skype call, with general analytics related questions + little sql exercise. Second round in person. A round of five separate interviews at Facebook HQ in Euston, each with a different flavour, some more general analytics/BI, some more technical (e.g. coding exercise, sql etc). Some interviewers were very approachable and easy to talk to, some others much less. There was one case when I honestly thought the person interviewing me had something against me or was upset for some reason, as their behaviour was very rude and confrontational. I am a very peaceful person usually so I let it go. Probably Facebook asked some random employees to come over from their HQ in the US to do these interviews in change of a little paid vacation in London. I suppose some of them were affected by the jet lag more than others. Overall it was a good experience; it looked like the day was very well organised.

First a brief introduction of yourself. Then why you choose facebook. The following is an online coding question using mysql. Then question about like/dislike system in the facebook. How to choose emotions and any problems in the A/B test. This question is quite hard and I didn't get it until the interviewer gave a lot of hints.