Rails and PostgreSQL: Role postgres does not exist

I have installed PostgreSQL on my Mac OS Lion, and am working on a rails app. I use RVM to keep everything separate from my other Rails apps.

For some reason when I try to migrate the db for the first time rake cannot find the postgres user. I get the error

 FATAL:  role "postgres" does not exist

I have pgAdmin so I can clearly see there is a postgres user in the DB - the admin account in fact - so I'm not sure what else to do.

I read somewhere about people having issues with PostgreSQL because of which path it was installed in, but then I don't think I would have gotten that far if it couldn't find the db.

Solution 1:

Actually, for some unknown reason, I found the issue was actually because the postgresql role hadn't been created.

Try running:

createuser -s -r postgres

Note that roles are the way that PostgreSQL maintains database permissions. If there is no role for the postgres user, then it can't access anything. The createuser command is a thin wrapper around the commands CREATE USER, CREATE ROLE, etc.

Solution 2:

Recently i got this problem immediately after installing postgres. If it comes immediately after installation, you might be missing the default user, postgres. In that case, you can create default user postgres using below command.

createuser -s -U $USER

Ex: createuser -s -U $USER
enter your required role name: postgres
enter password for your the user: 

It will prompt you to enter required database role name and password Once you complete the process, you can login to the postgres console using below command

psql -U 'your_database_name'

Ex: psql -U postgres
Here, You need to enter the password if you have given any, while creating the user.

Hope it helps :)