22.2. Role Attributes
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 theLOGIN
attribute can be considered the same as a " database user " . To create a role with login privilege, use either:CREATE ROLE
name
LOGIN; CREATE USERname
;(
CREATE USER
is equivalent toCREATE ROLE
except thatCREATE USER
includesLOGIN
by default, whileCREATE 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
. You must do this as a role that is already a superuser.name
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
. A role withname
CREATEROLECREATEROLE
privilege can alter and drop other roles, too, as well as grant or revoke membership in them. Altering a role includes most changes that can be made usingALTER ROLE
, including, for example, changing passwords. It also includes modifications to a role that can be made using theCOMMENT
andSECURITY LABEL
commands.However,
CREATEROLE
does not convey the ability to createSUPERUSER
roles, nor does it convey any power overSUPERUSER
roles that already exist. Furthermore,CREATEROLE
does not convey the power to createREPLICATION
users, nor the ability to grant or revoke theREPLICATION
privilege, nor the ability to modify the role properties of such users. However, it does allowALTER ROLE ... SET
andALTER ROLE ... RENAME
to be used onREPLICATION
roles, as well as the use ofCOMMENT ON ROLE
,SECURITY LABEL ON ROLE
, andDROP ROLE
. Finally,CREATEROLE
does not confer the ability to grant or revoke theBYPASSRLS
privilege.Because the
CREATEROLE
privilege allows a user to grant or revoke membership even in roles to which it does not (yet) have any access, aCREATEROLE
user can obtain access to the capabilities of every predefined role in the system, including highly privileged roles such aspg_execute_server_program
andpg_write_server_files
. - 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, useCREATE 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
andmd5
authentication methods make use of passwords. Database passwords are separate from operating system passwords. Specify a password upon role creation withCREATE ROLE
.name
PASSWORD 'string
' - inheritance of privileges
-
A role is given permission to inherit the privileges of roles it is a member of, by default. However, to create a role without the permission, use
CREATE ROLE
.name
NOINHERIT - 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
as a superuser.name
BYPASSRLS - 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 20 . 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
.
Note that role-specific defaults attached to roles without
rolename
RESET
varname
LOGIN
privilege are fairly useless, since they will never
be invoked.