psql: FATAL: role “postgres” does not exist

问题:

I'm a postgres novice.

I installed the postgres.app for mac. I was playing around with the psql commands and I accidentally dropped the postgres database. I don't know what was in it.

I'm currently working on a tutorial: http://www.rosslaird.com/blog/building-a-project-with-mezzanine/

And I'm stuck at sudo -u postgres psql postgres

ERROR MESSAGE: psql: FATAL: role "postgres" does not exist

$ which psql

/Applications/Postgres.app/Contents/MacOS/bin/psql 

This is what prints out of psql -l

                                List of databases     Name    |   Owner    | Encoding | Collate | Ctype |     Access privileges      ------------+------------+----------+---------+-------+---------------------------  user       | user       | UTF8     | en_US   | en_US |   template0  | user       | UTF8     | en_US   | en_US | =c/user                  +             |            |          |         |       | user      =CTc/user        template1  | user       | UTF8     | en_US   | en_US | =c/user                  +             |            |          |         |       | user      =CTc/user       (3 rows) 

So what are the steps I should take? Delete an everything related to psql and reinstall everything?

Thanks for the help guys!

回答1:

Note that the error message does NOT talk about a missing database, it talks about a missing role. Later in the login process it might also stumble over the missing database.

But the first step is to check the missing role: What is the output within psql of the command \du ? On my Ubuntu system the relevant line looks like this:

                              List of roles  Role name |            Attributes             | Member of  -----------+-----------------------------------+-----------  postgres  | Superuser, Create role, Create DB | {}         

If there is not at least one role with superuser, then you have a problem :-)

If there is one, you can use that to login. And looking at the output of your \l command: The permissions for user on the template0 and template1 databases are the same as on my Ubuntu system for the superuser postgres. So I think your setup simple uses user as the superuser. So you could try this command to login:

sudo -u user psql user 

If user is really the DB superuser you can create another DB superuser and a private, empty database for him:

CREATE USER postgres SUPERUSER; CREATE DATABASE postgres WITH OWNER postgres; 

But since your postgres.app setup does not seem to do this, you also should not. Simple adapt the tutorial.

回答2:

The key is "I installed the postgres.app for mac." This application sets up the local PostgresSQL installation with a database superuser whose role name is the same as your login (short) name.

When Postgres.app first starts up, it creates the $USER database, which is the default database for psql when none is specified. The default user is $USER, with no password.

Some scripts (e.g., a database backup created with pgdump on a Linux systsem) and tutorials will assume the superuser has the traditional role name of postgres.

You can make your local install look a bit more traditional and avoid these problems by doing a one time:

/Applications/Postgres.app/Contents/Versions/9.*/bin/createuser -s postgres 

which will make those FATAL: role "postgres" does not exist go away.

回答3:

For MAC:

1. Install Homebrew
2. brew install postgres
3. initdb /usr/local/var/postgres
4. /usr/local/Cellar/postgresql/<version>/bin/createuser -s postgres

---

To start server at startup

• mkdir -p ~/Library/LaunchAgents
• ln -sfv /usr/local/opt/postgresql/*.plist ~/Library/LaunchAgents
• launchctl load ~/Library/LaunchAgents/homebrew.mxcl.postgresql.plist

---

Now, it is set up, login using psql -U postgres -h localhost or use PgAdmin for GUI.

By default user postgres will not have any login password.

Check this site for more articles like this: https://sites.google.com/site/nitinpasumarthy/blog/installingpostgresonmac

回答4:

For me, this code worked:

/Applications/Postgres.app/Contents/Versions/9.4/bin/createuser -s postgres 

it came from here: http://talk.growstuff.org/t/fatal-role-postgres-does-not-exist/216/4

回答5:

createuser postgres --interactive 

or make a superuser postgresl just with

createuser postgres -s 

回答6:

First you need create a user:

sudo -u postgres createuser --superuser $USER 

After you create a database:

sudo -u postgres createdb $USER 

Change $USER to your system username.

You can see the the complete solution here.

回答7:

Running this on the command line should fix it

/Applications/Postgres.app/Contents/Versions/9.4/bin/createdb <Mac OSX Username Here>

回答8:

Dropping the postgres database doesn't really matter. This database is initially empty and its purpose is simply for the postgres user to have a kind of "home" to connect to, should it need one.

Still you may recreate it with the SQL command CREATE DATABASE postgres;

Note that the tutorial mentioned in the question is not written with postgres.app in mind. Contrary to PostgreSQL for Unix in general, postgres.app tries to look like a normal application as opposed to a service that would be run by a dedicated postgres user having different privileges than your normal user. postgres.app is run and managed by your own account.

So instead of this command: sudo -u postgres psql -U postgres, it would be more in the spirit of postgres.app to just issue: psql, which automatically connects to a database matching your users's name, and with a db account of the same name that happens to be superuser, so it can do anything permissions-wise.

回答9:

For what it is worth, i have ubuntu and many packages installed and it went in conflict with it.

For me the right answer was:

sudo -i -u postgres-xc psql 

回答10:

I ran into this issue following a PostgreSQL build using Homebrew due to an OpenSSL conflict.

I suggest the following:

Reinstall OpenSSL

brew remove openssl brew install openssl 

Force symlink creation of OpenSSL

brew link --force openssl 

Create new role I should note that, for security purposes, my setup involves an administrator account that is separate from my standard account. The accounts below can be tweaked as necessary.

sudo -u <administrator account> createuser <standard account> -d -P 

This method will create a database using the <standard account> as a name, as well as setting up a password for it. The flags at the end can be removed if this is not desired.

Finally, postgresql operations, such as createdb <dbname> can be used without the FATAL errors prior.

回答11:

I don't think that sudo is needed here because psql -l returns a list of databases. This tells me that initdb was run under the user's current user, not under the postgres user.

You can just:

psql 

And continue the tutorial.

I would suggest A.H's general points of creating the postgres user and db because many applications may expect this to exist.

A brief explanation:

PostgreSQL will not run with administrative access to the operating system. Instead it runs with an ordinary user, and in order to support peer authentication (asking the OS who is trying to connect) it creates a user and db with the user that runs the initialization process. In this case it was your normal user.

回答12:

This is the only one that fixed it for me :

createuser -s -U $USER 

回答13:

I needed to unset $PGUSER:

$ unset PGUSER $ createuser -s postgres 

回答14:

I became stuck on this issue having executed brew services stop postgresql the day prior.
The day following: brew services start postgresql would not work. This is because as is shown when you install using homebrew. postgresql uses a launchd ... which loads when your computer is powered on.

resolution:
brew services start postgresql
Restart your computer.

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