Question

i’m running a social network site and i currently have most main user data (real name, username, email, password, gender, etc) in a user table. Design-wise, would there be an performance improvement in moving the username+password to a separate table ?

I’m using mysql.

Answer 1

Authentication queries which only need username and password will run slightly faster, due to the smaller size of the table.

However, if you create a composite index on (username, password_hash), it will be even faster, since the queries like this:

SELECT  password_hash
FROM    users
WHERE   username = 'myusername'

will only need the index to run (it will show using index in the plan).