PostgreSQL
21.2. Role Attributes
A database role can have a number of attributes that define its privileges and interact with the client authentication system.
- [.term]#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 “[.quote]#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.) [.term]#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. [.term]#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 .term]#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 other roles, too, as well as grant or revoke membership in them. 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. + Because the `+CREATEROLE+` privilege allows a user to grant or revoke membership even in roles to which it does not (yet) have any access, a `+CREATEROLE+` user can obtain access to the capabilities of every predefined role in the system, including highly privileged roles such as `+pg_execute_server_program+` and `+pg_write_server_files+`. [.term]#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+`. [.term]#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+`_`+'+`. [.term]#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+`. [.term]#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. [.term]#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.
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21.3. Role Membership |
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