21.2. Role Attributes

21.2. Role Attributes
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A database role can have a number of attributes that define its privileges and interact with the client authentication system.

login privilege

Only roles that have the LOGIN attribute can be used as the initial role name for a database connection. A role with the LOGIN attribute can be considered the same as a " database user " . To create a role with login privilege, use either:

CREATE ROLE name LOGIN;
CREATE USER name;

( CREATE USER is equivalent to CREATE ROLE except that CREATE USER includes LOGIN by default, while CREATE ROLE does not.)

superuser status

A database superuser bypasses all permission checks, except the right to log in. This is a dangerous privilege and should not be used carelessly; it is best to do most of your work as a role that is not a superuser. To create a new database superuser, use CREATE ROLE name SUPERUSER . You must do this as a role that is already a superuser.

database creation

A role must be explicitly given permission to create databases (except for superusers, since those bypass all permission checks). To create such a role, use CREATE ROLE name CREATEDB .

role creation

A role must be explicitly given permission to create more roles (except for superusers, since those bypass all permission checks). To create such a role, use CREATE ROLE name CREATEROLE . A role with CREATEROLE privilege can alter and drop roles which have been granted to the CREATEROLE user with the ADMIN option. Such a grant occurs automatically when a CREATEROLE user that is not a superuser creates a new role, so that by default, a CREATEROLE user can alter and drop the roles which they have created. Altering a role includes most changes that can be made using ALTER ROLE , including, for example, changing passwords. It also includes modifications to a role that can be made using the COMMENT and SECURITY LABEL commands.

However, CREATEROLE does not convey the ability to create SUPERUSER roles, nor does it convey any power over SUPERUSER roles that already exist. Furthermore, CREATEROLE does not convey the power to create REPLICATION users, nor the ability to grant or revoke the REPLICATION privilege, nor the ability to modify the role properties of such users. However, it does allow ALTER ROLE ... SET and ALTER ROLE ... RENAME to be used on REPLICATION roles, as well as the use of COMMENT ON ROLE , SECURITY LABEL ON ROLE , and DROP ROLE . Finally, CREATEROLE does not confer the ability to grant or revoke the BYPASSRLS privilege.

initiating replication

A role must explicitly be given permission to initiate streaming replication (except for superusers, since those bypass all permission checks). A role used for streaming replication must have LOGIN permission as well. To create such a role, use CREATE ROLE name REPLICATION LOGIN .

password

A password is only significant if the client authentication method requires the user to supply a password when connecting to the database. The password and md5 authentication methods make use of passwords. Database passwords are separate from operating system passwords. Specify a password upon role creation with CREATE ROLE name PASSWORD ' string ' .

inheritance of privileges

A role inherits the privileges of roles it is a member of, by default. However, to create a role which does not inherit privileges by default, use CREATE ROLE name NOINHERIT . Alternatively, inheritance can be overridden for individual grants by using WITH INHERIT TRUE or WITH INHERIT FALSE .

bypassing row-level security

A role must be explicitly given permission to bypass every row-level security (RLS) policy (except for superusers, since those bypass all permission checks). To create such a role, use CREATE ROLE name BYPASSRLS as a superuser.

connection limit

Connection limit can specify how many concurrent connections a role can make. -1 (the default) means no limit. Specify connection limit upon role creation with CREATE ROLE name CONNECTION LIMIT ' integer ' .

A role's attributes can be modified after creation with ALTER ROLE . See the reference pages for the CREATE ROLE and ALTER ROLE commands for details.

A role can also have role-specific defaults for many of the run-time configuration settings described in Chapter 19 . For example, if for some reason you want to disable index scans (hint: not a good idea) anytime you connect, you can use:

ALTER ROLE myname SET enable_indexscan TO off;

This will save the setting (but not set it immediately). In subsequent connections by this role it will appear as though SET enable_indexscan TO off had been executed just before the session started. You can still alter this setting during the session; it will only be the default. To remove a role-specific default setting, use ALTER ROLE rolename RESET varname . Note that role-specific defaults attached to roles without LOGIN privilege are fairly useless, since they will never be invoked.

When a non-superuser creates a role using the CREATEROLE privilege, the created role is automatically granted back to the creating user, just as if the bootstrap superuser had executed the command GRANT created_user TO creating_user WITH ADMIN TRUE, SET FALSE, INHERIT FALSE . Since a CREATEROLE user can only exercise special privileges with regard to an existing role if they have ADMIN OPTION on it, this grant is just sufficient to allow a CREATEROLE user to administer the roles they created. However, because it is created with INHERIT FALSE, SET FALSE , the CREATEROLE user doesn't inherit the privileges of the created role, nor can it access the privileges of that role using SET ROLE . However, since any user who has ADMIN OPTION on a role can grant membership in that role to any other user, the CREATEROLE user can gain access to the created role by simply granting that role back to themselves with the INHERIT and/or SET options. Thus, the fact that privileges are not inherited by default nor is SET ROLE granted by default is a safeguard against accidents, not a security feature. Also note that, because this automatic grant is granted by the bootstrap superuser, it cannot be removed or changed by the CREATEROLE user; however, any superuser could revoke it, modify it, and/or issue additional such grants to other CREATEROLE users. Whichever CREATEROLE users have ADMIN OPTION on a role at any given time can administer it.

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