if the salt is random, how do we reliably generate the same salt value
I was confused about this as well. You store the hash of the random, long salt in the user table right next to the hash of the password. It’s not a secret, so you don’t have to hide it.
Are you sure about that? Since hashes are one way, how would you compare a randomly salted password with a provided creditential with out knowing the (unhashed) salt?