EXL Service Data Engineer interview questions

How will you eliminate duplicate records

I didn't like their interview process. There was no HR who will contact you to regarding interview date and time. The interviewer at the screening level starting conversing on whatsapp which is not at all professional. Next day morning it was a telephonic round on basics of Big Data, Spark,Python. later on, another level of whatsapp video call interview happened, no HR contacted regarding time and day of the interview. The interviewer himself called on whatsapp via video call. This was not a professional way of calling an interviewee. Next day another senior person(maybe a manager) called me to meet them at Gurgaon location. On asking about interview call letter/mail by HR he seemed disinterested and told will drop a message of company location in Gurgaon. I didn't went for this F2F interview as it seemed highly unprofessional.