I was contacted on LinkedIn by a recruiter. Recruiter was extremely professional and helpful. He gave me the good advice to prepare for 1 or 2 easy/medium leetcode q's for phone round everyday for 3 weeks and I did exactly that. I bought the leetcode premium package where i was able to do the Facebook track and a lot of questions i got throughout the process were similar to one there. For phone round, i was asked 3sum + bunch of SQL questions related to department/salary and applied/recruiter data sets which you can find on glassdoor and leetcode. Some SQL questions were slightly tricky and I was glad i prepared. The interviewer was passionate about his job and answered a lot of questions. I setup onsite soon after phone, recruiter sent me a lot of material and also did a phone call to help prepare. As I started preparing for the onsite interview and reading a little bit about the role, it appeared that the data engineer role at facebook is not as appealing as the Software engineer role and it was validated during the interview where i learnt that 2 of the interviewers were transitioning to software engineering roles - this was a red flag for me because I have a long and solid background in CS and data eng. The product sense question was confusing because I wasn't sure what the interviewer wanted but i guess they just wanted ERD and database schema, maybe they should call it that? because i started with client-server diagrams etc which was not needed. I like some of the ETL questions, it was fun to solve. The behavior round was also fun. I was skeptical but the time went by quickly. The recruiter had sent some very good material which helped me with other interviews as well. I should add that I interviewed for the Enterprise engineering team which i learnt during the process supports the Product team. If it was more clear to me, I would have probably tried to interview in the Product team , because looked like people were trying to move from Enterprise engineering to product >< haha Overall good process, i did not get an offer but i was hooked up with another recruiter in Facebook where they thought I might be a good match. I chose not to pursue that .