Q1. Why is authorisation token part of the header of the http request?
Q2. You have 100M customers who are going to log in to your app at exactly 5 pm. You need to show all of them personalised videos of length around 3-5 mins at the same time i.e, 5 pm. However, your system supports ( after maximum horizontal and vertical scaling ) a maximum of 10M users simultaneously for video streaming? What are the technical challenges in this ? How will solve this problem?
Q3. You have a database in the form of a table which is sparse and does not have a primary key (the entire row represents a record). You need to support the following operations on it -

1. Add( Row r). You will be given all the cells of a row to add
2. Delete (Row r). You will be given all the cells of row to delete. There will be only one row which will match this. Find it and delete it.
3. Update(Row updatedRow). You will be given all the cells of row to update. This row will be identical to exactly one row in the database except one cell. Find that row and update it.

I was looking for the answers to these questions. Can someone share their solutions?