SET ROLE
SET ROLE — set the current user identifier of the current session
Synopsis
SET [ SESSION | LOCAL ] ROLE role_name
SET [ SESSION | LOCAL ] ROLE NONE
RESET ROLE
Description
This command sets the current user identifier of the current SQL session to be
role_name. The role name can be written as either an identifier or a string
literal. After SET ROLE, permissions checking for SQL commands is carried out
as though the named role were the one that had logged in originally.
The current session user must have the SET option for the specified role_name, either directly or indirectly via a chain of memberships with the SET option. (If the session user is a superuser, any role can be selected.)
The SESSION and LOCAL modifiers act the same as for the regular SET command.
SET ROLE NONE sets the current user identifier to the current session user
identifier, as returned by session_user. RESET ROLE sets the current user
identifier to the connection-time setting specified by the command-line options,
ALTER ROLE, or ALTER DATABASE, if any such settings exist. Otherwise,
RESET ROLE sets the current user identifier to the current session user
identifier. These forms can be executed by any user.
Notes
Using this command, it is possible to either add privileges or restrict one's
privileges. If the session user role has been granted memberships WITH INHERIT
TRUE, it automatically has all the privileges of every such role. In this case
SET ROLE effectively drops all the privileges except for those which the target
role directly possesses or inherits. On the other hand, if the session user
role has been granted memberships WITH INHERIT FALSE, the privileges of the
granted roles can't be accessed by default. However, if the role was granted
WITH SET TRUE, the session user can use SET ROLE to drop the privileges
assigned directly to the session user and instead acquire the privileges available
to the named role. If the role was granted WITH INHERIT FALSE, SET FALSE then
the privileges of that role cannot be exercised either with or without SET ROLE.
Note that when a superuser chooses to SET ROLE to a non-superuser role, they
lose their superuser privileges.
SET ROLE has effects comparable to SET SESSION AUTHORIZATION, but the
privilege checks involved are quite different. Also, SET SESSION AUTHORIZATION
determines which roles are allowable for later SET ROLE commands, whereas
changing roles with SET ROLE does not change the set of roles allowed to a
later SET ROLE.
SET ROLE does not process session variables as specified by the role's
ALTER ROLE settings; this only happens during login.
SET ROLE cannot be used within a SECURITY DEFINER function.
Examples
SELECT SESSION_USER, CURRENT_USER;
session_user | current_user
--------------+--------------
peter | peter
SET ROLE 'paul';
SELECT SESSION_USER, CURRENT_USER;
session_user | current_user
--------------+--------------
peter | paul
Compatibility
QHB allows identifier syntax ("rolename"), while the SQL standard requires the role name to be written as a string literal. SQL does not allow this command during a transaction; QHB does not make this restriction because there is no reason to. The SESSION and LOCAL modifiers are a QHB extension, as is the RESET syntax.