Wondering how to use “alter user” to superuser postgres? We can help you.

As part of our Server Management Services, we assist our customers with several postgres queries.

Today, let us see how our techs proceed with the process.

How to use “alter user” to superuser postgres?

Modifying user permissions within PostgreSQL can range from rather simple to extremely complex.

Depending on the permissive granularity that is actually require.

In most cases, however, it is the powerful ALTER USER command that should utilize to do everything from allowing users to login, create databases, manage roles, and even become a SUPERUSER account.

Today, let us see the procedure followed by our Support Techs.

Creating a New User

Before we get into altering user permissions, we should establish a new user account.

To begin, we’ll list all the existing users:

=# SELECT usename FROM pg_user;
usename
----------
postgres
(1 row)

By default, postgres is typically the only user that exists, so we want to create a new user of librarian to control our library database.

We can accomplish this using the CREATE USER command:

=# CREATE USER librarian;
CREATE ROLE
=# SELECT usename FROM pg_user;
usename
-----------
postgres
librarian
(2 rows)

Viewing Existing User Permissions

Often, useful to examine the existing permissions assigned to the users in the system.

This can easily accomplished with the \du command from the psql prompt:

=# \du
List of roles
Role name | Attributes | Member of
-----------+------------------------------------------------+-----------
librarian | | {}
postgres | Superuser, Create role, Create DB, Replication | {}

We can clearly see that even though we’ve now added a new librarian user, we have to assign it some permissions.

Altering Existing User Permissions

Now that our librarian user exists, we can begin using ALTER USER to modify the permissions granted to librarian.

The basic format of ALTER USER includes the name of the user (or ROLE) followed by a series of options to inform PostgreSQL which permissive alterations to make:

=# ALTER USER role_specification WITH OPTION1 OPTION2 OPTION3;

These options range from CREATEDB, CREATEROLE, CREATEUSER, and even SUPERUSER.

Additionally, most options also have a negative counterpart, informing the system that you wish to deny the user that particular permission.

These option names are the same as their assignment counterpart, but are prefixed with NO (e.g. NOCREATEDB, NOCREATEROLE, NOSUPERUSER).

Assigning SUPERUSER Permission

We can use the SUPERUSER option to assign our librarian user SUPERUSER permission:

=# ALTER USER librarian WITH SUPERUSER;
ALTER ROLE

Sure enough, if we display our permission list now, we’ll see librarian has the new SUPERUSER permission we want:

=# \du
List of roles
Role name | Attributes | Member of
-----------+------------------------------------------------+-----------
librarian | Superuser | {}
postgres | Superuser, Create role, Create DB, Replication | {}

Revoking Permissions

In the event that we make a mistake and assign a permission we later wish to revoke.

Simply issue the same ALTER USER command but add the NO prefix in front of the permissive options to be revoked.

For example, we can remove SUPERUSER from our librarian user like so:

# alter="" user="" librarian="" with="" nosuperuser;<br="">ALTER ROLE
=# \du
List of roles
Role name | Attributes | Member of
-----------+------------------------------------------------+-----------
librarian | | {}
postgres | Superuser, Create role, Create DB, Replication | {}

[Stuck in between? We’d be glad to assist you]

Conclusion

In short, today we saw how our Support Techs go about to use “alter user” to superuser postgres.