CREATE ROLE · PostgreSQL 中文文档 9.3

# CREATE ROLE ## Name CREATE ROLE -- 定义一个新的数据库角色 ## Synopsis ``` CREATE ROLE _name_ [ [ WITH ] _option_ [ ... ] ] where `_option_` can be: SUPERUSER | NOSUPERUSER | CREATEDB | NOCREATEDB | CREATEROLE | NOCREATEROLE | CREATEUSER | NOCREATEUSER | INHERIT | NOINHERIT | LOGIN | NOLOGIN | REPLICATION | NOREPLICATION | CONNECTION LIMIT _connlimit_ | [ ENCRYPTED | UNENCRYPTED ] PASSWORD '_password_' | VALID UNTIL '_timestamp_' | IN ROLE _role_name_ [, ...] | IN GROUP _role_name_ [, ...] | ROLE _role_name_ [, ...] | ADMIN _role_name_ [, ...] | USER _role_name_ [, ...] | SYSID _uid_ ``` ## Description `CREATE ROLE` 命令用于为PostgreSQL数据库集群增加新的角色。角色是拥有数据库对象和数据库权限的实体。一个角色可以依据其被使用的情况，被看做一个用户"user"或者一个组 "group"。参考[Chapter 20](#calibre_link-13)和[Chapter 19](#calibre_link-14)这两个文档，去获取有关用户和认证管理的相关信息。你必须要有`CREATEROLE`权限，或者你是一个超级用户，你才能使用 `CREATE ROLE`命令。注意，角色是定义在数据库集群级别的，所以在集群中的所有数据库中都是有效的。 ## 参数 `_name_` 新角色的名称。 `SUPERUSER``NOSUPERUSER` 这两个条件决定一个新的角色是否为一个超级用户（"superuser"），超级用户可以超越数据库内的所有访问限制。超级用户状态是危险的，应该在真正需要的情况下才被使用。你自己必须是一个超级用户，才能创建一个新的超级用户。如果没有指定这个条件，缺省是 `NOSUPERUSER`。 `CREATEDB` `NOCREATEDB` 这两个条件定义用户创建数据库的权限。如果被指定为`CREATEDB`，则该用户被赋予创建数据库的权限。被指定为`NOCREATEDB` 将没有创建数据库的权限。如果没有指定这个条件，缺省是`NOCREATEDB` 。 `CREATEROLE` `NOCREATEROLE` 这两个条件决定一个角色是否被允许创建新角色（即，执行`CREATE ROLE`命令的权限）。一个角色如果被赋予`CREATEROLE`权限，则同时也具有了修改或删除其他角色的权限。如果没有指定这个条件，则缺省是 `NOCREATEROLE`。 `CREATEUSER` `NOCREATEUSER` 这两个条件是过时的，不过现在仍被数据库接受，他们和条件`SUPERUSER` `NOSUPERUSER`是等效的。注意，他们和 `CREATEROLE` `NOCREATEROLE`并无关系。 `INHERIT` `NOINHERIT` These clauses determine whether a role "inherits" the privileges of roles it is a member of. A role with the `INHERIT` attribute can automatically use whatever database privileges have been granted to all roles it is directly or indirectly a member of. Without `INHERIT`, membership in another role only grants the ability to `SET ROLE` to that other role; the privileges of the other role are only available after having done so. If not specified, `INHERIT` is the default. `LOGIN` `NOLOGIN` These clauses determine whether a role is allowed to log in; that is, whether the role can be given as the initial session authorization name during client connection. A role having the `LOGIN` attribute can be thought of as a user. Roles without this attribute are useful for managing database privileges, but are not users in the usual sense of the word. If not specified, `NOLOGIN` is the default, except when `CREATE ROLE` is invoked through its alternative spelling [CREATE USER](#calibre_link-15). 这两个参数决定一个角色是否有登进数据库的权限；一个拥有`LOGIN`属性的角色（role），可以被视为一个用户（user）。 `REPLICATION` `NOREPLICATION` These clauses determine whether a role is allowed to initiate streaming replication or put the system in and out of backup mode. A role having the `REPLICATION` attribute is a very highly privileged role, and should only be used on roles actually used for replication. If not specified, `NOREPLICATION` is the default. `CONNECTION LIMIT` `_connlimit_` If role can log in, this specifies how many concurrent connections the role can make. -1 (the default) means no limit. `PASSWORD` `_password_` Sets the role's password. (A password is only of use for roles having the `LOGIN` attribute, but you can nonetheless define one for roles without it.) If you do not plan to use password authentication you can omit this option. If no password is specified, the password will be set to null and password authentication will always fail for that user. A null password can optionally be written explicitly as `PASSWORD NULL`. `ENCRYPTED` `UNENCRYPTED` These key words control whether the password is stored encrypted in the system catalogs. (If neither is specified, the default behavior is determined by the configuration parameter [password_encryption](#calibre_link-16).) If the presented password string is already in MD5-encrypted format, then it is stored encrypted as-is, regardless of whether `ENCRYPTED` or `UNENCRYPTED` is specified (since the system cannot decrypt the specified encrypted password string). This allows reloading of encrypted passwords during dump/restore. Note that older clients might lack support for the MD5 authentication mechanism that is needed to work with passwords that are stored encrypted. `VALID UNTIL` '`_timestamp_`' The `VALID UNTIL` clause sets a date and time after which the role's password is no longer valid. If this clause is omitted the password will be valid for all time. `IN ROLE` `_role_name_` The `IN ROLE` clause lists one or more existing roles to which the new role will be immediately added as a new member. (Note that there is no option to add the new role as an administrator; use a separate `GRANT` command to do that.) `IN GROUP` `_role_name_` `IN GROUP` is an obsolete spelling of `IN ROLE`. `ROLE` `_role_name_` The `ROLE` clause lists one or more existing roles which are automatically added as members of the new role. (This in effect makes the new role a "group".) `ADMIN` `_role_name_` The `ADMIN` clause is like `ROLE`, but the named roles are added to the new role `WITH ADMIN OPTION`, giving them the right to grant membership in this role to others. `USER` `_role_name_` The `USER` clause is an obsolete spelling of the `ROLE` clause. `SYSID` `_uid_` The `SYSID` clause is ignored, but is accepted for backwards compatibility. ## Notes Use [ALTER ROLE](#calibre_link-17) to change the attributes of a role, and [DROP ROLE](#calibre_link-18) to remove a role. All the attributes specified by `CREATE ROLE` can be modified by later `ALTER ROLE` commands. The preferred way to add and remove members of roles that are being used as groups is to use [GRANT](#calibre_link-19) and [REVOKE](#calibre_link-20). The `VALID UNTIL` clause defines an expiration time for a password only, not for the role _per se_. In particular, the expiration time is not enforced when logging in using a non-password-based authentication method. The `INHERIT` attribute governs inheritance of grantable privileges (that is, access privileges for database objects and role memberships). It does not apply to the special role attributes set by `CREATE ROLE` and `ALTER ROLE`. For example, being a member of a role with `CREATEDB` privilege does not immediately grant the ability to create databases, even if `INHERIT` is set; it would be necessary to become that role via [SET ROLE](#calibre_link-21) before creating a database. The `INHERIT` attribute is the default for reasons of backwards compatibility: in prior releases of PostgreSQL, users always had access to all privileges of groups they were members of. However, `NOINHERIT` provides a closer match to the semantics specified in the SQL standard. Be careful with the `CREATEROLE` privilege. There is no concept of inheritance for the privileges of a `CREATEROLE`-role. That means that even if a role does not have a certain privilege but is allowed to create other roles, it can easily create another role with different privileges than its own (except for creating roles with superuser privileges). For example, if the role "user" has the `CREATEROLE` privilege but not the `CREATEDB` privilege, nonetheless it can create a new role with the `CREATEDB` privilege. Therefore, regard roles that have the `CREATEROLE` privilege as almost-superuser-roles. PostgreSQL includes a program [createuser](#calibre_link-22) that has the same functionality as `CREATE ROLE` (in fact, it calls this command) but can be run from the command shell. The `CONNECTION LIMIT` option is only enforced approximately; if two new sessions start at about the same time when just one connection "slot" remains for the role, it is possible that both will fail. Also, the limit is never enforced for superusers. Caution must be exercised when specifying an unencrypted password with this command. The password will be transmitted to the server in cleartext, and it might also be logged in the client's command history or the server log. The command [createuser](#calibre_link-22), however, transmits the password encrypted. Also, [psql](#calibre_link-23) contains a command `\password` that can be used to safely change the password later. ## Examples Create a role that can log in, but don't give it a password: ``` CREATE ROLE jonathan LOGIN; ``` Create a role with a password: ``` CREATE USER davide WITH PASSWORD 'jw8s0F4'; ``` (`CREATE USER` is the same as `CREATE ROLE` except that it implies `LOGIN`.) Create a role with a password that is valid until the end of 2004. After one second has ticked in 2005, the password is no longer valid. ``` CREATE ROLE miriam WITH LOGIN PASSWORD 'jw8s0F4' VALID UNTIL '2005-01-01'; ``` Create a role that can create databases and manage roles: ``` CREATE ROLE admin WITH CREATEDB CREATEROLE; ``` ## Compatibility The `CREATE ROLE` statement is in the SQL standard, but the standard only requires the syntax ``` CREATE ROLE _name_ [ WITH ADMIN _role_name_ ] ``` Multiple initial administrators, and all the other options of `CREATE ROLE`, are PostgreSQL extensions. The SQL standard defines the concepts of users and roles, but it regards them as distinct concepts and leaves all commands defining users to be specified by each database implementation. In PostgreSQL we have chosen to unify users and roles into a single kind of entity. Roles therefore have many more optional attributes than they do in the standard. The behavior specified by the SQL standard is most closely approximated by giving users the `NOINHERIT` attribute, while roles are given the `INHERIT` attribute. ## See Also [SET ROLE](#calibre_link-21), [ALTER ROLE](#calibre_link-17), [DROP ROLE](#calibre_link-18), [GRANT](#calibre_link-19), [REVOKE](#calibre_link-20), [createuser](#calibre_link-22)