database design for 'followers' and 'followings'?

Question

Dear database experts/programmers:

I have a mysql table with users information, such as

id      user_id         name etc.
1       userA            
2         


        

Answer 1

General tip. Use integers for ids rather than strings. There is a significant performance difference. So drop users.user_id, and rename users.id to users.user_id. Secondly your followers table should have indexes on user_id and follower_id. Again there is a significant performance benefit. I also like the idea of having a unique index on (user_id, follower_id), calling that your primary key, and dropping your id column.